When you play in your garden, you may have noticed that rocks and soil seem to go together naturally. You now know how rocks are formed, but how are they related to soil particles? Where does soil come from? In a way, one can say that rock is the mother of soil. The process of weathering is a key in the relationship between rocks and soil. If you look at` the Elephant Rocks in New Zealand, they are exposed to various physical and chemical conditions that alter their form and composition. One can assume that some soil particles surrounding them also originate from them. How is weathering related to soil formation?
Rock is a solid substance that can be found on Earth’s surface. Underneath all the soil and water is a layer of rocks that comprise the planet’s surface. Rocks are products of natural geological processes. A rock may be composed of one or more minerals. It can also be a combination of minerals and once living materials such as shells of animals or parts of plants that died a very long time ago. A mineral is a solid, non-living, and naturally occurring substance on Earth. As soon as rocks get exposed to various agents, it starts to break down.
Weathering is the process of wearing away or breaking down of rocks into smaller pieces. It is a long and gradual process that, along with other processes, continuously changes the shape of Earth’s surface. A mountain today may be a plain after millions of years because of weathering.
Weathering can be caused by the physical break down of rocks or by the help of chemicals that dissolve parts of rocks slowly. Agents of weathering are factors that enable the breaking down or dissolving of rocks. In Fig. 1 and 2, can you imagine the role of water in the process of weather and in shaping a mountain?
Mechanical Weathering
Mechanical weathering is the process where rocks are broken down into smaller particles because of physical processes. The agents of mechanical weathering are temperature, wind, water, abrasive forces, and living organisms. All of these agents contribute to the natural geological mechanism of wearing down rocks into particles that will contribute to the soil.
Factors Driving Mechanical Weathering
Temperature
Temperature changes every day and throughout the year. It is typically colder at night and hotter during the day when the sun is up. There are months that are colder or hotter in a year. A rock that is constantly exposed to changing temperature is affected gradually. Rocks contract when it is cold and expand when it is hot. The repeated contraction and expansion of rocks will result in cracks.
Wind and Water
Wind and water can cause rocks to tumble or bump into each other repeatedly which cause them to crack or break. Wind and flowing water bring with them small materials that rub against rocks, which in turn scrape their surfaces.
Abrasion
Abrasion is the rubbing together of two materials which results in the wearing away of their surfaces. Abrasive action can be compared to the back and forth movement of sandpaper that is used to polish or smoothen wood surfaces. Portions of rock surfaces come off as the wind or water passes along and rubs against the rock. Repeated abrasion by wind and flowing water results in the polished or smooth appearance of weathered rocks.
Living Things
Living things like plants, animals, and humans can cause the breaking down of rocks too. Plant roots can force through cracks and eventually break down rocks. Actions of animals such as burrowing can create holes and can also force rocks to crack and eventually break. Human activities contribute a lot to weathering. Humans use resources from rocks to build roads, shelter, factories, and many more. Human activities also use rocks directly or expose them to weathering through other agents.
Chemical Weathering
Chemical weathering is the breaking down of rocks due to chemical changes that involve water, acids, and gases like oxygen. Chemical weathering changes the minerals in rocks and causes new substances to form.
Factors Driving Chemical Weathering
Water and Formation of Acids
Water and acids can combine chemically with minerals that are exposed in rocks. Minerals that are chemically combined with water can be washed away and leave holes on rocks. Carbon dioxide can combine with water chemically to form carbonic acid. Carbonic acid can dissolve limestone and carve out holes through time. Most caves are formed from the action of carbonic acid in limestone. Acid rain that results from air pollutants combined chemically with rainwater also dissolves minerals in rocks. As dissolved minerals are washed away, the space they occupy in rocks is left as holes.
Oxidation
Oxidation occurs when some minerals are exposed to oxygen from air. More specifically, the iron content in some rocks forms rust when exposed to oxygen. When rust formation increases in rocks, it will also eventually break down rocks.
Role of Weathering in Soil Formation
Weathering does not involve the movement of broken down fragments of rocks. Where do broken rocks go? Some weathered materials are carried and deposited to other areas by different agents such as wind and water. Recalling the rock cycle, some weathered materials change into sedimentary rocks when cemented together under water. However, weathered materials can also accumulate for a long period of time and eventually become soil.
Soil is a mixture of broken down fragments of rocks, air spaces, water, and organic matter. Organic matter consists of material from dead plants and animals.
Soil formation begins with the weathering of rocks. Plants that grow on weathered rocks help in breaking it down more. Plants are able to use the nutrients from the minerals in rocks. When plants die, they become part of the organic matter in the soil. More plants will be able to grow on the soil, and this also means that more plants are able to draw out the minerals from rocks. Animals will survive in areas with plants. When animals die, they also add to the organic matter in soil.
Soil has different layers, and each is called a horizon. The combined layers of soil are referred to as its profile. A typical soil profile can give a glimpse of how the soil is formed.
The lowest horizon is the bedrock. The bedrock comprises the rock that is often the parent material of the soil. Weathering of the bedrock starts the soil formation. Above the bedrock is the parent rock which is made up of residual bedrock and followed by the subsoil horizon which is made of loose, slightly weathered rocks, and exposed minerals with very little organic matter. Above the subsoil is the topsoil, a horizon with the complete mixture of weathered rocks, organic matter, air, and water. It is the horizon where plants can get most of the available nutrients from minerals and organic matter.
Have you seen signs along the road that say “Watch for falling debris” or “Caution: landslide-prone area?” There are areas with such signs along mountain roads in the countryside. Parts of land can move through the process called erosion, and sometimes it happens without warning. It continuously changes the shape of the Earth’s surface and, at times, in a dangerous way. However, we have to acknowledge that these are natural processes that occur in our lithosphere, only that some human activities tend to increase their rates. What is the process of erosion and why does it happen?
Erosion is the removal of weathered rocks and soil and their transfer to another location. Deposition is the settling down of eroded materials in a new location. Erosion then stops when materials are deposited and settled in the new location. Weathering, erosion, and deposition are related natural processes that influence the shape of our planet.
Natural Causes of Erosion
Water, wind, ice, and gravity are the natural agents of erosion. Erosion can be described based on the action of each agent.
Wind Erosion
Wind erosion is common in dry places like deserts and the polar regions. In dry areas, sand, soil, snow, or debris is not held together by moisture or roots of plants. Those materials can easily be swept away when strong winds blow. Dunes are mounds of sand that are similar to hills in shape. In deserts, dunes are formed when sand gets blown by the wind.
Water Erosion
Water erosion is caused by the force of moving water in rain, ocean waves, and river current. Rain carries loose particles that are not being held together by the roots of plants. Floodwater that flows has more energy than individual raindrops, and it can transport more and larger particles with it.
River current flows from mountains to the sea. River water transports sediments as it moves. Materials carried by the water flow can also scrape off parts of the banks and bottom of the river and carve the shape of the land where the river flows.
The rocks and soil carved out of the banks and bottom add to the sediments being carried off along the river. When the speed of river flow decreases, sediments will be deposited and settled. The deposition of river sediments near the mouth of the river creates landforms such as floodplains and river deltas.
Avalanche
In colder regions where ice forms in mountains, ice is an agent of weathering and erosion. Ice that covers a big part of a mountain has a great weight that can scrape off rocks and soil under it. When it moves, it can carry rocks of any size and shape, including soil particles. An example of ice movement is an avalanche. It is a sudden downward flow of snow and ice from the mountains. Rocks and soil are carried with ice in an avalanche.
Gravity
Gravity causes erosion by pulling rocks, soil, and other materials downward. The weight of rocks and soil, as well as their position, can be affected by gravity. Rocks and soil that are located in sloping areas can fall down due to their weight. Gravity can cause a landslide or the sudden downward movement of a large chunk of land on a slope. Gravity also aids water and ice erosion. When water and ice are along slopes, the pull of gravity allows more materials to be carried downward.
Human-Induced Soil Erosion
Erosion also occurs due to human activities. Some of these activities that can lead to erosion are deforestation, mining, agriculture, and other development activities.
Deforestation
Deforestation is the removal of trees from forests. Trees support the topsoil by holding it in place and absorbing rainwater. Trees also reduce the impact of rainwater drops on the soil. Removal of trees means there is nothing that can stop the soil from being eroded by wind, water, or gravity.
Mining
Mining is the extraction of valuable minerals from soil and rocks. People use machines that remove large amounts of rock and soil from the ground to obtain mineral resources such as coal, copper, iron, and aluminum. Mining methods include removing the soil to get through the rocks underground, breaking large boulders of rocks, and dissolving minerals within rocks.
Agricultural Activities
Agricultural methods and practices can cause soil erosion. Examples of these practices are the following:
● The repeated plowing of soil and harvesting of plants remove the soil that goes with plant roots.
● Excessive use of chemical fertilizers reduces the quality of soil and make it more prone to erosion by water.
● Overgrazing can change the quality of soil and render it unsuitable for plants. Without plants, overgrazed areas can be eroded by wind, water, or gravity.
● Removal of trees in sloping areas in order to plant crops can make the soil prone to erosion when it rains or due to gravity.
Human Infrastructures
Development projects such as infrastructure or road construction involve the use of rock and soil resources. These activities remove rocks and soil in certain locations to construct different structures. Roads are carved out in mountains in order to transport machines that can extract resources from mining. Afterward, these resources are used to build other structures. Every time there is a new construction, a corresponding erosion is directly caused by humans.
Soil Erosion and Deposition
Soil erosion results in the deposition of soil to another location. The eroded soil is washed away by the flow of water and is deposited to another location. Over time, soil sediments that collect in another location can pile up into another landform such as floodplains and delta. There are areas wherein the bedrock is not the parent material of the topsoil. It is due to the deposition of eroded soil from another area.
Soil Erosion and Soil Degradation
What happens to the land where the soil is eroded from? Loss of topsoil through erosion results in soil degradation. Soil degradation is the decrease in the quality and fertility of soil to support plants and animals. Topsoil has available nutrients from the humus and highly weathered rocks and minerals. It is the layer of the soil where plants and animals live. Plants can draw nutrients and anchor their roots on the topsoil because the air and water spaces make the soil easier to penetrate compared to the denser and more solid subsoil.
Soil Erosion and River Siltation
River siltation is another term to describe the gathering of soil sediments in rivers. Sediments in rivers take up space and change the amount and quality of nutrients available for plants and animals that live in it. How do you think that affects animals and plants in rivers?
River siltation can change the quality of fish farms and reduce the fish yield. Laguna Bay is a lake that receives water from the rivers and streams in the mountains that surround it. Many communities around the lake rely on fish farms as part of their main livelihood.
Sediments carried into the lake change the quality of water and space in the fish farms. What do you think is its effect on the livelihood of the people in those communities?
Soil Erosion and Its Impact to Community
Soil erosion is a natural process that happens slowly over time. However, human activities can hasten and increase their impacts on communities. To see the effects of soil erosion, pretend you are experimenting with the setup here.
Human Activities that Cause Soil Erosion in the Philippines
Deforestation, mining, and infrastructure development all hasten and increase the impact of soil erosion. The Sierra Madre mountain range that traverses Luzon from North to South is rich in forest and mineral resources. Because of this richness, many mountains in the range are locations of activities such as deforestation, mining, and other development projects. Last August 2, 2017, it was reported by CNN Philippines that flooding and landslides due to typhoon Noru affected many areas in Luzon. Classes were suspended that day in East Luzon such as Rizal and nearby cities due to flooding. There were also road closures in the mountainous areas of Northern Luzon due to landslides triggered by the typhoon.
Sediments take up space in rivers and streams due to soil erosion. Water that cannot be absorbed by plants, soil, rivers, and streams will overflow in normally dry areas, causing a flood. Flood is water that collects in normally dry areas.
Sloping areas are more prone to erosion due to water and gravity. Landslides can occur with or without the help of water. But landslides occur more frequently in the rainy season. The high amount of water that adds to the weight of the soil can trigger landslides.
Flooding and landslides are two of the most common effects of soil erosion in the Philippines, especially during the typhoon season. They are so common that when there is heavy rain, people are expecting traffic problems and class suspensions due to floods and landslides.
In the Philippines, drastic changes in the physical landscape due to soil erosion can be observed immediately in the rainy season. Landslide and flooding are considered disasters if the normal activities of communities are hindered by them. Rivers can be blocked and flooding will be its consequence. Houses, roads, farms, and other structures can fall or be buried under chunks of land. Flood currents can carry away people and properties as well as structures. Contrary to slow natural erosion, the negative impacts of landslides and flooding are immediately felt in the community.
Soil erosion is a serious problem in the Philippines. However, communities cannot thrive without using soil for agriculture and their other needs. Some rural areas even resort to the conversion of forested areas into agricultural lands to generate greater yield. In some other areas, lands are being converted into residential communities. Is it possible for people to benefit from the soil without destroying it? How can communities utilize soil while preventing soil erosion?
Soil conservation pertains to methods and practices to prevent soil erosion and soil degradation. Historically, small communities practice sustainable farming. Sustainable farming includes soil conservation practices such that the soil can continue to be fertile even after continuous farming. As communities grow in size, the need for bigger farmlands led to many forests being converted into farms. The need for increased food production depleted the soil of its nutrients faster than it can recover. Deforestation and agricultural land conversion have increased the soil erosion problem. As people recognized the impact of human activities on soil loss, some traditional methods were improved and other methods were developed to conserve the soil.
Soil Conservation Methods
Crop Rotation
Crop rotation is described as raising different crops in the same area, in a sequence throughout the year or in the following years. For example, after growing corn in an upland farm, upland rice can be planted. Afterward, cassava or peanuts may be planted. When different crops are planted, different nutrients from the soil will be obtained by plants. When the remains of crops are incorporated into the soil, they will be added to the organic matter for the next group of plants.
Strip Farming
The different plants with different kinds of roots would imply that nutrients will be obtained from different parts of the soil. Soil structures will also be more resistant to soil erosion when roots penetrate different depths of soil.
Strip farming can also be done for the same purpose as crop rotation. Instead of growing different plants in sequence, different rows can be planted with different kinds of crops. For example, corn and soybeans can be planted in alternating rows.
Mulching
Mulching is covering the exposed soil layer with organic matter such as grasses, twigs, or leaves. Some mulches can be plants that grow close to the ground such as short grasses. Mulching will prevent the soil from drying up because it covers the soil, and it will also lessen the chances of soil erosion from wind and water. The mulch itself can add to the humus of the topsoil.
Crop rotation, strip farming, and mulching improve soil quality and fertility. Such methods help in making the land suitable for farming for a long period of time. In addition, these methods decrease the chances of soil being exposed to wind and water, the major agents of erosion.
Tree Planting
Trees, in general, help decrease the effects of soil erosion as their roots anchor to the soil. Planting trees along the edges of farms and in sloping areas can act as physical barriers against wind and water. Several reforestation projects are being launched by the government to plant more trees in barren lands to restore their environmental health status.
Contour Plowing
Contour plowing or plowing and planting crops across the slope of the land will reduce the amount of water that flows downwards when it rains. When crops are planted in rows from top to bottom, water runs off faster in between the rows. In contour plowing, crops across the slope catch the water and decrease the speed of water flow.
Terraces
Terracing is a famous method of planting rice in Asian countries. Terracing involves carving the slope-like stairs. The water that flows from the higher parts of the slope will be caught by the terraces and used by the crops that are planted there. Banaue Rice Terraces in the Cordillera region is a famous heritage of the Filipinos. The terracing method of communities in Cordillera includes maintaining forest patches in the highest parts of the terraces.
Soil Conservation Awareness
Soil conservation practices can be done in any size of land in any area. Are there soil conservation methods that can be observed in your community? There can be other soil conservation practices that are done in your community. Soil conservation should not be a concern only for farmers. Remember that soil erosion is not only due to farming. Everyone benefits from farming and other human activities that affect soil erosion. Soil conservation needs the effort not just of selected individuals but of the whole community. One can always find a way to contribute to soil conservation efforts. There are concerned groups and organizations that help promote soil conservation practices. Other organizations appeal to lawmakers to create laws that will reduce soil erosion or promote the use of soil conservation practices. Students can help by studying other ways to promote soil conservation in their homes and communities.
The weather pattern in an area allows one to plan activities that would be suitable for the day. There are times when extreme weather conditions disrupt the regular weather pattern, which can be dangerous when one is not prepared. In the Philippines, we experience several weather disturbances that often cause calamities. Typhoons are expected to happen during the rainy season in the Philippines. Typhoons can be considered as dangerous weather phenomena. What is a typhoon and how does it form?
A weather disturbance is a general term that refers to a severe weather condition that can be destructive to communities. It is different from normal weather patterns because, although it happens less frequently, a weather disturbance can be dangerous to communities. Thunderstorms, tropical cyclones, and tornadoes are examples of weather disturbances.
Types of Weather Disturbance
Thunderstorm
A thunderstorm is a weather disturbance that can occur during any season in the Philippines. It is characterized by a heavy rain shower with lightning and thunder. Thunderstorm clouds form from rapidly rising warm air that carries with it a large amount of water vapor. Thunderstorm clouds are cumulonimbus clouds that can look like large cauliflowers or anvils.
As storm clouds continue to form fast high in the atmosphere, condensed ice or water droplets collide and bump into each other and rub off their electric charges. The rapid collision of these particles can result in a buildup of electric charges. Lightning is the release of these electric charges in clouds. The sound waves produced by lightning generate what can be heard as thunder. Aside from heavy rains, lightning, and thunder, thunderstorms can bring about hail, strong winds, and tornadoes that can all cause destructive effects, such as flooding and damage to properties.
Tornado
A tornado is a violently spinning column of air that extends from the base of a cumulonimbus cloud to the ground. Tornadoes are not always visible as they are made of air. However, a tornado becomes visible if it has enough condensed water droplets, dust, and other debris that are sucked in as it rotates.
Tornadoes move very fast and have a very high energy that can destroy anything in its path. Meteorologists, or scientists who specialize in the study of the atmosphere, are still trying to understand how and when tornadoes form. Prediction of when a tornado will occur is important to prevent disasters. For now, it is known that the most violent tornadoes usually form at the base of very large thunderstorm clouds called supercells. Supercell clouds sometimes form condensation funnels or moving condensed columns of clouds that form at their base.
Meteorologists look out for signs, such as condensation funnels when in cumulonimbus clouds. When condensation funnels do not touch the ground, they are called funnel clouds. When a condensation funnel touches the ground, it is already classified as a tornado.
Tropical Cyclone
A tropical cyclone is characterized by a large mass of storm clouds rotating around a low-pressure center. It is usually given different names depending on where it has developed. If it is formed over the Atlantic or Northeast Pacific Oceans, the tropical cyclone is referred to as a hurricane. If it is formed over the South Pacific Ocean or the Indian Ocean, it is called a cyclone. In the Northwest Pacific Ocean, a cyclone that forms is called a typhoon. Southeast Asian countries, such as the Philippines, experience typhoons from the Northwest Pacific Ocean. Tropical cyclones cannot form nor cross the equator. Hurricanes occur usually around June to October, typhoons occur around May to November, and cyclones form around December to April of each year. However, changes in global climate can affect the regular occurrences of tropical cyclones.
Tropical cyclones form along the regions of the oceans near the equator where the water temperature is 26 °C or higher. When there is a right mix of water vapor and winds over warm ocean waters, tropical cyclone clouds develop, and these storm clouds can start to rotate. A tropical cyclone that moves at a sustained speed that exceeds 118 kilometers per hour is classified as a typhoon, hurricane, or cyclone, depending on where it formed. Tropical cyclones derive their energy from the heat, wind, and water cycle processes over the oceans. Tropical cyclones can travel over the oceans with greater energy but weaken when they reach land. As tropical cyclones move to land, they can bring with them violent winds, storm surges, heavy rains, and floods.
A typhoon is a tropical cyclone that develops over the warm waters of the Northwest Pacific Ocean. A typhoon develops in the presence of the following:
1. large space over and above the ocean regions in the tropical zone,
2. water ocean temperature of at least 26 °C to a depth of at least 46 meters, and
3. wind that reaches high in the atmosphere.
As ocean water evaporates, the warm moist air rises high above the atmosphere, carried by the winds. The space left by the rising warm air becomes a low-pressure area, and cooler air will flow toward it. As the water vapor condenses into clouds, heat is released into the atmosphere. The heat released makes the warm, moist air lighter, causing it to rise higher in the atmosphere. As more warm, moist air evaporates and condenses, clouds continue to form and move around the low-pressure center. The rotating movement of air as it flows from higher pressure to lower pressure area are the winds of the typhoon.
Typhoon Structure
A typhoon is a system composed of different parts. If you view a typhoon from space, it looks like a swirling group of clouds around a hole in the middle. The center that may appear to look like a hole is the typhoon’s eye. The eye is bordered by a thick wall of clouds called an eyewall, and around it are the swirling clouds that form the rainbands.
The typhoon’s eye is the low-pressure area in its center. It is where cool air continuously sinks into as the warm air around it continuously rises. The eye of the typhoon is its calmest part. If you are inside the eye of the typhoon, the winds are gentle and there is no rain. During a typhoon, the weather will calm down as the eye passes over an area.
The eyewall is composed of high columns of thick thunderstorm clouds surrounding the eye. It is the part of the typhoon with the highest amount of energy; thus, it is where the winds are strongest and rains are heaviest.
Thunderstorm clouds that surround the eyewall in a spiral make up the rainbands. The clouds that make up the rainbands produce thunderstorms. There are instances where gaps are found in between the rainbands such that some typhoons can have periods with no rain or light rains and periods with heavy rains. Wind speed in rainbands is faster near the center and slower in the outer parts of the band.
Stages of Typhoon Development
A typhoon undergoes stages of development until it loses its energy and dies. At its formative stage, a cluster of cumulus clouds shows a weak spiraling movement. When this group of clouds moves at a speed of 36 kilometers per hour, it is already classified as a tropical depression.
If the wind speed increases to 62 kilometers per hour, it is classified as a tropical storm. As a tropical storm, the winds can die down or intensify, depending on the condition of the atmosphere. If wind speed intensifies and sustains a maximum speed of 89 kilometers per hour, it is categorized as a severe tropical storm. Furthermore, if it exceeds 118 kilometers per hour, it is called a typhoon. A tropical cyclone with more than 220 kilometers per hour maximum wind speed is categorized as a super typhoon.
A typhoon is already at its mature stage wherein the eye is formed. The area covered by the typhoon expands, and its maximum speed can be sustained for a week. A typhoon reaches its decaying stage when its winds weaken as it loses its energy. At this stage, the air pressure in the eye increases, and the wind speed decreases. Typhoons usually lose their energy as they move over land where there is less moisture or when they move toward the poles where the air is colder.
View the Formation of a tropical cyclone here.
Changes in the Weather Before, During, and After a Typhoon
A typhoon is a large weather system that can cover a large area of land. It can even cover the whole Philippines, so when it is nearing your place, swirling clouds will not be evident. A typhoon is said to have made a landfall if its eye reaches land. Even if it has not made a landfall, the rainbands and the eyewall can still reach and affect land.
Although the whole typhoon system cannot be seen from your location, it is still possible to observe the changes in the weather if a typhoon is approaching. Prior to a typhoon, the air will feel cold and dry. Dark clouds forming that can cover the horizon or the whole sky above are also noticeable. During a typhoon, violent winds and heavy rains can be experienced with possible periods of calm weather in between rainbands. When the winds are strongest and the rain is heaviest, the eyewall is passing through your location. If you are near the coast, you can notice the big waves slamming on the coastline brought about by the winds.
A sudden calm and quiet weather will be experienced as the eye of the typhoon passes through. You can expect the calm to be followed by strong winds and heavy rains as the eyewall reaches your place again. The typhoon is strongest near the coast and becomes weaker as it goes inland where the moisture is less than above the ocean. After a typhoon, you can expect a calm weather and a clearer sky.
Causes of Weather Disturbances in the Philippines
Due to the location of the Philippines, the country tends to experience weather disturbances that are considered to be unique to its position. The following are the common causes of weather disturbances in the Philippines:
Easterly Waves
These are the east-to-west flow trade winds. Most of the time, the trade wind speed ranges from about 16 kph to 19 kph. Once it is properly distributed, the wind speed can reach the maximum value of 24 kph. Given the optimum condition, easterly wind can develop into a tropical cyclone.
Intertropical Convergence Zone (ITCZ)
It is the region where the wind from the northern hemisphere exchanges with the windcoming from the southern hemisphere. ITCZ is characterized by the presence of numerous cumulonimbus clouds that cause showers and wide-coverage thunderstorms.
See the Wind movement in the Earth’s hemisphere here.
Monsoon
Large volumes of the rainfalls in the Philippines are caused by the presence of the northwest monsoon (amihan) together with the southeast monsoon (habagat). A monsoon is a wind system that is formed due to the differences in temperature and pressure between the oceans of the continents.
Cold Fronts
Cold fronts are weather disturbances caused by the temperature in the region. In winter, the northern hemisphere cold front is usually experienced in the Philippines. The front commonly brings a large volume of precipitation or rainfall but decreases as it reaches the Philippines. A cold front normally induces cloudy weather with occasional rains.
Typhoon Haiyan (locally known as Yolanda) is known as one of the strongest typhoons that left sad memories in the history of the Philippines. Haiyan tore across Central Visayas in November of 2013 and left the region in a state of calamity. The affected areas were left with damaged infrastructure, livelihood, and more than six thousand people dead or missing. What are the effects of typhoons in communities?
Typhoon Hazards
Typhoons bring with it massive thunderstorm clouds and strong winds. The strength of the typhoon and the amount of rainfall that comes from a typhoon can be a serious threat to communities that are in its path. The hazards or potentially damaging events or phenomena of a typhoon are the following.
Heavy Rain
Heavy rain for long periods of time can cause flooding and landslides, especially to deforested and sloping areas.
Strong Winds
Strong winds can exceed the speed of 220 kilometers per hour. Strong winds can break or uproot trees, destroy weak structures like poorly built houses, and carry with them other objects and debris that are in their path. In water, strong winds can make waves strong and turbulent or cause storm surges, making it highly dangerous for any activity in or near bodies of water.
Storm Surge
Storm surge is the sudden and abnormal rise in the water level above the predicted tide, due to the strong winds of a typhoon. Storm surge can occur not only in oceans but in other bodies of water too. The spinning winds of a typhoon push surface water as it travels, causing this surge. When a storm surge reaches the shore, high-energy water waves can enter the land and cause flooding and destruction of objects in its path. Due to their proximity to coasts, communities close to the shore are affected first by storm surges.
Tornadoes
Tornadoes, although uncommon in the Philippines, are still possible especially during a typhoon. Depending on their strength, tornadoes can suck up objects, dust, and debris within their vortex or the rotating column of air as they travel.
Effects of Typhoon Hazards to Communities
Destruction of Infrastructures
Strong winds and tornadoes can damage properties. They can also cause objects to be aloft at great speed. Dust and debris that are carried by strong winds or tornados can strike other objects and cause greater damage. Imagine a metal sheet of a house roof flying towards a car or a person. This situation can really be dangerous to people and other objects nearby.
Destruction of Farmlands and Crops
In farming communities, crops can be damaged as winds bend and break the plants in farmlands. Thus, strong typhoons can bring about significant losses in the agricultural sector due to crops that become unavailable to the market to damages.
Electricity Blackout
Winds can also damage communication and electricity lines. Electricity companies sometimes turn off the power supply temporarily to prevent further damages due to the dangers of electricity.
Travelling Hazards
Travelling is dangerous when there are strong winds. The wind can oppose the movement of a vehicle, be it a bike, a car, a boat, or a plane. The dust and debris in the wind would also make it dangerous for anyone to travel.
Landslide
Rain is beneficial to communities because it adds to the water supply for both people and the environment. However, heavy rains can be too much for the land to soak, and this can result in landslides and flooding.
In a landslide, the weight of water-soaked soil causes large chunks of mud and rocks to fall off sloping areas such as hills and mountains. In sloping areas without trees, landslides are more likely to happen. Houses and other structures in sloping areas or at the foot of hills or mountains are in danger of being buried by landslides.
Flash Floods
Heavy rains and storm surges can cause flooding. When there is a storm surge, the flood water level can rise very quickly as water enters the land at a great speed. Flood water can enter roads and houses, too. Communities near the coastline are the ones immediately affected by storm surges. The strong water current of floodwater can carry objects and even people with it. Fish ponds can overflow, causing fish and other aquatic food to be lost as well. Crops and other livestock can drown in the flood, too.
Typhoons can cause damage to people, properties, and livelihood. Typhoon damage can be classified as a disaster if it causes serious disruption of the normal functions of the community. Floodwater, loss of food, water, and other basic needs can greatly impact one’s health. Floodwaters can cause diseases such as leptospirosis, which can affect the community. Damaged houses can force people to evacuate. Buildings such as schools are often used as evacuation centers, and this results in the disruption of classes too. Electricity lines and roads that are damaged can disrupt the normal activities that people do every day.
Threats to Food Security
Lost crops and livestock damage the livelihood of farmers, and fishermen cannot go to the seas because of the strong winds and waves. The lack of food supply due to damaged crops and livestock will result in higher prices of food, making it harder for people to buy.
When you watch weather reports in the news, you will often hear storm warning signals during typhoons. Classes in elementary and high school are automatically suspended when PAGASA declares a storm signal number two or higher. It can be assumed that the higher the storm signal is, the worse the weather condition is. What do different storm warning signal numbers represent?
Philippine Area of Responsibility
The Philippines is in the path of many typhoons that develop in the Pacific Ocean. The Philippine area of responsibility (PAR) is the region surrounding the Philippines that PAGASA monitors regarding changes in the atmosphere.
Here is the Philippine Area of Responsibility.
The number of typhoons and developing typhoons that entered the Philippine Area of Responsibility (PAR) is at least twenty in a year. Not all developing typhoons and mature typhoons make landfall when they enter the PAR, but they all affect the local weather in different areas in the country.
This is The number of typhoons in the Philippines (PAGASA).
Public Storm Warning Signals
Typhoons have different sizes and strengths, and PAGASA has studied the dangers that are possible with different types of typhoons. To have the means of warning the citizens about the dangers of an incoming typhoon, PAGASA developed the public storm warning signals (PSWS) to inform the public about an incoming typhoon.
During an expected typhoon, a weather bulletin with a specific public storm warning signal (PSWS) is released to provide information and warning ahead of time. The strength of the signal corresponds to the strength of the typhoon’s wind speed. The table below shows the storm warning signals developed for public information.
This shows the Public Storm Warning Signals in the Philippines.
The table above shows the PSWS and the typhoon’s corresponding wind speed, the effective period of the wind speed stated, and the possible impacts of the wind. The increasing number of PSWS corresponds to increasing wind speed and decreasing lead time before reaching your area.
When PAGASA first announces a PSWS, a typhoon has entered the PAR but is not yet felt in the affected areas. It is given so that there would be time for people to prepare for the expected hazards of the typhoon. Different PSWS numbers are given to different areas, depending on the movement of the typhoon and how it will affect an area.
For example, on October 3, at 2:00 p.m., PSWS No. 2 was assigned to Metro Manila while it is PSWS No. 3 in provinces Bulacan, Pampanga, and Nueva Ecija. In the example, it means that within 24 hours from the time the signal was given, wind speeds of 61 to 120 kilometers per hour can be expected in Metro Manila. However, within 18 hours, a wind speed of 121–170 kilometers per hour can affect the provinces of Bulacan, Pampanga, and Nueva Ecija.
This is a comparison of different typhoon classification to different transportation/vehicles.
If PSWS No. 2 is given, it means that the speed of the typhoon (up to 120 kph) is faster than the allowed speed of cars on major highways. It is a government policy that classes from elementary to high school are suspended at PSWS No. 2. The hazards associated with this storm signal make it unsafe for students to leave their homes and family. In addition, for people living in coastal areas, sea waves usually reach 4 to 14 meters. Storm surge is also possible. By contrast, for PSWS No. 3, sea waves usually reach more than 14 meters.
As shown in here, PSWS No. 1 corresponds to a tropical depression wherein wind speed is similar to a man riding a bicycle. Next is the tropical storm that moves as fast as a man on a motorcycle. During PSWS No. 1, sea waves can usually reach from 1.24 to 4 meters. A severe tropical storm, on the other hand, is similar to the speed of a car. Going to a higher level, a typhoon moves as fast as a train. Lastly, a super typhoon has a speed similar to a bullet train. With this, you will have an idea of how fast weather disturbance moves. Just take note that its speed decreases as it hits the land. Thus, given these severe weather conditions, houses with medium-built materials may experience collapsed walls and unroofing.
Here is the Philippine rainfall warning system.
Shown here is a diagram of all the typhoons in the Northern Pacific Ocean from 1980 to 2005. The lines show the path of each typhoon in colors blue, red, and yellow. The number of typhoon tracks covering the Philippines except for a small portion of Mindanao gives you an idea of how frequent typhoons reach the country as it moves across the ocean.
Precautionary Measures for Typhoons
You already know the hazards and the possible effects of a typhoon in the community. Preparedness for a typhoon starts with knowing what to do before, during, and after it. In preparing for a typhoon, two important questions can help you think of what to prepare:
1. How can typhoon-related hazards be prevented?
2. If such hazards cannot be prevented, how can the damages that would result from them be lessened or recovered?
A typhoon is a weather disturbance that occurs in the Philippines with some regularity. This means that Filipinos can expect them to happen and prepare for its eventuality. A typhoon is a natural phenomenon that cannot be prevented. However, preparing for a typhoon can prevent or minimize its negative impact on everyone’s life.
Precautionary Measures Before a Typhoon
● Be informed about your surroundings. Check if your house is in an open field, at high elevation, a sloping land, near a body of water, surrounded by mountains, or in a flood-prone area. Your location and the state of the environment in your area can give you an idea of possible hazards such as flooding, landslides, storm surges, or damages from winds.
● Hold a family meeting and plan the things that you will do in case you need to evacuate. Establish a communication plan in case not everyone is in the house during a typhoon. The communication plan will help you contact one another and ensure everyone’s safety.
● Prepare an emergency survival kit that includes but is not limited to the following:
○ flashlight and battery-operated radio
○ batteries
○ packed food that can be kept for long periods of time and in easy-to-open containers (ex. canned food, instant noodles, biscuits, etc.)
○ simple tools (ex. scissors)
○ first aid kit
○ drinking water in a safely-sealed container
○ blankets
○ emergency numbers
○ copy of important documents
● Secure the area around and in your house against strong winds by doing the following:
○ cut off tree branches that can break and damage electrical wires and glass windows
○ repair loose roofing, hinges, etc.
○ clean awnings, gutters, downspouts, and canals
○ secure glass windows
● If you live on the upper floors of a tall building (more than ten floors), plan for a temporary shelter on the lower floors.
● Secure your house from floods.
○ Elevate house furniture and electrical appliances.
○ Place temporary water barriers outside your doors or gates, such as sandbags.
● Monitor the weather by listening to news updates.
● Keep your mobile phones charged.
Precautionary Measures During a Typhoon
● Be updated about the typhoon’s track by monitoring the news.
● Do not travel. Do not attempt to leave the house even if the weather calmed for a bit. It could probably be because the eye must be passing.
● Check and make sure everyone in the house knows where the emergency survival kits are. Review your evacuation and communication plan.
● Close doors and windows. Keep curtains closed.
● Stay away from doors and windows.
● If the winds are too strong or if there is a threat of flooding, turn off the main electricity switch inside your house.
● Conserve the batteries of your mobile devices. Refrain from using mobile phones other than for monitoring family members.
● Prepare to evacuate anytime.
Precautionary Measures After a Typhoon
● Monitor the news for updates about the weather and the status of the community.
● Inspect your house and surroundings for damages.
● Stay away from doors and windows.
● Be careful when using electrical devices and ensure that they are not wet as they may cause electric shock. As much as possible, also stay away from power lines.
● If possible, let authorities know about fallen electric lines or trees that may endanger other people’s lives.
● Ensure to cook your food well and drink only clean water.
When you look at the night sky at different times of the month, do you observe the same size and shape of the moon? On some nights, you can see the moon, full and bright. On other nights, you can also see a small part. On some rare occasions, you cannot see the entire Moon. What do you think affects the size and shape of the moon?
Before you understand what affects the size and shape of the moon as seen by an observer on Earth, you must learn about its characteristics first. The moon that you see at night seems to be flat and hollow as it reflects light, but it is made up of rocks. It has a rocky surface with plenty of craters or large, bowl-shaped empty spaces. The craters were formed due to the impact of other heavenly objects, such as asteroids, meteoroids, and comets, that hit the moon’s surface. The moon has a very thin and weak blanket of gas called the exosphere. It does not have enough strength to protect the moon’s surface when an asteroid or comet collides with it.
The Surface of the Moon
Have you noticed the light and dark areas on the moon’s surface? The light areas of the moon are called highlands, while the dark areas are known as maria, which originated from the Latin word for seas. The highlands and maria represent the different compositions and ages of rocks present in the Moon. The highlands are composed of the oldest rocks on the moon—about the same time when the moon was formed. During the succeeding years, the moon’s surface was bombarded by meteoroids, which created craters.
The maria formed when dark lavas filled these craters. The moon appears large when seen at night not because of its average size but due to its close proximity to Earth. The distance between the moon and Earth is 384,400 kilometers, while the actual radius of the moon is only 1,737.5 kilometers. Among the many moons found in the solar system, Earth's moon is the fifth largest. Since the moon is relatively close to Earth, it is the only place in outer space where humans have reached.
The distance of Earth to the Moon in light seconds (1 light second is equivalent to 299, 792 km).
The moon follows a certain path known as orbit as it moves or revolves around Earth. It also moves together with Earth and revolves around the sun. This movement allows the moon to reflect the light of the Sun back to Earth.
Here is the Perigee and apogee.
Aside from reflecting the light of the sun back to Earth, the revolution of Moon also affects how big or small we see it from Earth. The Moon’s orbit is not circular, contrary to what we believe. It has an elliptical orbit. The perigee is the point in the moon’s orbit where it is nearest to Earth, whereas the apogee is the point in the orbit where it is farthest from Earth.
The relative distance of the moon from Earth changes how we see it from the planet. At its perigee, the Moon appears bigger whereas, at its apogee, it appears smaller. The moon actually appears 12% smaller in apogee when compared to its perigee as seen from Earth.
Here is the Comparison of the appearance of the moon during its perigee and apogee.
Comparison of Earth and Moon
Earth and Moon have similarities and differences. For instance, both Earth and Moon are made up of rocks. Earth and Moon are mostly made up of iron and are divided into three layers: crust, mantle, and core. However, the sizes of Earth and Moon differ. Earth is four times bigger and weighs eighty-one times more than the moon. This is the reason why Earth has a stronger gravitational pull than the moon.
In this figure, you will notice that Earth’s surface is mostly blue, while that of the moon is black and gray. Earth’s surface is covered mostly with water, which causes it to appear blue when observed from outer space. The presence of water on Earth makes it possible to support life. It also has a thick blanket of gas known as the atmosphere. Earth’s atmosphere is divided into several layers, makings it a good shield if asteroids will hit it.
On the other hand, the moon has a rocky surface with plenty of craters due to the weak exosphere that covers it. Another factor that determines the preservation of craters is erosion. Erosion is caused by moving water and wind. There are also craters on the surface of Earth. However, most of them are erased by erosion. On the other hand, the absence of water and wind in the moon makes it possible to preserve its numerous craters.
To this date, life is not possible on the moon, and continuous studies are being conducted to know more about its origin. Though the moon does not support life, it makes Earth a more habitable place. The gravitational pull of the moon on Earth makes the tides or regular rise and fall of sea surface possible. Tides influence several phenomena on Earth. For example, the behavior of marine organisms. The moon plays a significant role in the several processes and lifeforms on Earth.
When the sky is clear at night, you can see the moon shining brightly. But have you noticed that the moon’s shape changes from time to time? You might see it in its full shape one night, then witness its shape turn into half after a few nights? What could be the reason for this? Why does the moon seem to change its shape over time?
Shape of the Moon
The shape of the moon is not perfectly round. Instead, it is an oblate spheroid. It is like a normal ball that is slightly flattened. The moon does not actually change its shape as apparently seen in the night sky throughout a month. Rather, what changes is the observed sunlit part of the moon as it revolves around Earth. This results in changing the observed shape of the moon and the varying amount of light reflected from the sun to Earth.
The moon is seen in its different phases throughout the month.
The apparent changing shape of the moon as seen on Earth is known as the phases of the moon. The moon has different phases because it moves around Earth. Therefore, it changes its position with respect to Sun.
Phases of the Moon
To understand better how phases of the moon occur, it is important to realize first that just like Earth, half of the moon is always lit because it faces the sun, and the other half is in darkness. The lit part of the moon is the one that is observed on Earth at night. This lit part changes depending on the position of the moon with respect to the sun, which results in the different phases of the moon.
The revolution of Earth around the sun and of the moon around Earth results in the different phases of the moon.
The different phases of the moon are illustrated in here.
New Moon
When the moon is lined up between Earth and Sun, the new moon is observed. The side of the Moon facing Earth is not illuminated by the Sun, therefore, this part is in complete shadow. Only a very thin bright arc is observed.
Crescent Moon
The moon will then go to its waxing stage as it moves eastward away from the sun. In this stage, the illuminated part of the moon increases. A few days after the new moon, a thin arc known as the crescent moon is observed.
First Quarter
As nights pass, half of the moon will be illuminated. This is known as the first quarter. The illuminated part can either be the left or the right part of the moon. The lit side depends on your location on Earth. You can see the right part of the illuminated moon when you are located in the Northern Hemisphere, as seen here.
Waxing Gibbous
The moon will continue to wax until it reaches a phase wherein more than half of its surface is lit as seen on Earth. This phase is known as the waxing gibbous. In the Northern Hemisphere, the waxing phase is illuminated at the right side of the moon. It is better remembered as having a “D” shape, especially in the first quarter.
Full Moon
Each night, the gibbous moon appears to become fatter until the lit side of the Moon is fully seen on Earth. This phase is known as the full moon. During this time, the whole Moon is seen.
Waning Gibbous
After the full moon phase, the Moon starts to undergo the waning stage, wherein its illuminated part decreases. This is the part wherein people usually observe the moon becoming thinner as nights pass. From being fully lit, the moon starts to decrease its illuminated part and becomes a waning gibbous.
Last Quarter
Every night, the moon’s illuminated size decreases until it reaches a half-lit disc known as the last quarter. After a few days, the waning stage continues, and a thin arc or crescent moon appears until it approaches the new moon again.
Waning Crescent
In the waning phase, the illuminated part is the left side of the moon. It is characterized as having a “C” shape, especially the waning crescent.
Stars can be seen as white, shiny objects at night. But aside from what we physically see, stars have different characteristics that separate them from one another. They have other colors and they shine differently as well. These also form different patterns, referred to as constellations, that were also used by navigators in ancient times. What are the different characteristics of the stars? What are the different constellations that can be seen at night?
The Sun is the nearest star to Earth. It is the main source of heat and light energy, which are essential in supporting life. Like any other star, the sun is mainly composed of hot glowing gases such as hydrogen and helium. Other stars are not visible in the daytime because the sun outshines them. But at night, wherein one side of Earth is not facing the sun, other stars are visible and shining brightly.
Characteristics of Stars
There are millions of stars out there, with different sizes, masses, colors, and temperatures. Though they seem to be different from one another, they still share common features. For instance, all stars are made up of hot glowing gases. The glowing gases are a result of nuclear fusion, a kind of reaction that happens within the atoms of the given elements. This reaction allows the star to produce its own energy in the form of heat and light.
The gases within the stars are held together by a strong gravitational force. The strong gravitational force of a star also attracts objects around it. For example, the sun pulls the planets, moons, and other heavenly objects towards it, forming the solar system. Imagine if Sun will be taken away from the solar system, the entire system would collapse.
Color
Most of the stars you see at night appear to be white. But if you observe closely, the stars vary in color. Aside from white, the other colors of the stars are blue, yellow, orange, and red. The color of the star tells its temperature. The hotter the star is, the bluer its color, while the reddish stars have lower temperatures. The Sun is a yellow star which means it is not as hot as a blue star but has a higher temperature than a red star.
Stars vary in color, temperature, and size, see this illustration.
Size
At night, stars appear to be fixed points in the sky when observed with the naked eye. This is due to their great distance from Earth. However, stars vary in size and are categorized based on their diameter measurement. For instance, the smallest stars, known as the neutron stars, can measure from twenty to forty kilometers in diameter. The Crab Pulsar is an example of a neutron star. On the other hand, a white dwarf has a diameter almost similar to the size of Earth. The Proxima Centauri is considered a red dwarf. Next to the dwarf stars are giant stars which are 1,000 times bigger than the sun. Examples of giant stars are the blue giant, Rigel, and the red giant, Aldebaran. Stars that are bigger than giant stars may be classified as supergiants. Orion, Betelgeuse, and Antares are supergiants. There are also hypergiant stars. These stars have a diameter bigger than the orbit of Mars. An example of this is the UY Scuti.
A wide range of sizes of stars.
Luminosity
Luminosity is the total amount of energy radiated by a star and other celestial objects per second. A star is luminous when it is hot, large, or both. This means that a small, hot star can have the same luminosity as a large, cool star. There are many other stars seen in the night sky, some with names while others are still yet to be discovered and classified.
In this figure, a small, hot star can have the same luminosity as a large, cool star.
Twinkling Stars
Given that stars are made up of glowing gases, and are located very far from Earth, do stars really twinkle at night? The answer is no. Stars constantly radiate light, but the light they produce travels in a straight line. When light enters the atmosphere, it bends in different directions. Furthermore, it is affected by winds, temperature, and densities making them look sparkling. This is the reason why stars appear to twinkle when observed from Earth even though they do not at all.
Comparison of Earth and Stars
Earth and the stars have similarities and differences. Earth and stars have their own masses, which means they also possess gravitational force. This makes them pull objects towards them. For instance, Earth pulls the moon towards it since it has a stronger gravitational force. On the other hand, the sun pulls the planets and their moons towards it.
In this figure shows how earth is minuscule in size when compared to the sun.
In terms of shape, Earth is not perfectly round as it bulges on the sides and flattens on the pole. Most stars seem to be round, but they do not have a perfectly spherical shape either. In terms of composition, stars are made up of hot glowing gases, while Earth is composed of rocks. Stars, except for neutron stars, do not have a solid surface. It is mainly composed of glowing gases too. In contrast, Earth’s surface is being covered by land and water, which is also surrounded by a thick blanket of gas.
This figure shows the sun in comparison to other stars of mid-size.
In terms of size, some stars are much bigger than Earth. Take for example Sun which is 109 times bigger than Earth. However, other stars are smaller than Earth. These stars fall under the category of neutron stars. Given the characteristics of stars, life is not possible to thrive in them. However, the ability of stars to produce heat and light energy is necessary to support life, just like how Sun supports life on Earth.
What are Constellations?
The group of stars that form imaginary patterns in the sky was called a constellation. But in this modern day, constellations are not just imaginary patterns. A constellation is a set of stars with a recognized pattern in a region with well-defined boundaries. In other words, a constellation is a region in the sky and not just simple patterns. The International Astronomical Union (IAU) has identified a total of 88 constellations in the sky. Imagine that Earth is within a sphere where stars from different distances are lying on it. This imaginary sphere is known as the celestial sphere, and this is where constellations are found.
This shows the eighty-eight constellations are found in the imaginary celestial sphere.
Where Do the Constellations Get Their Names?
Animal Constellations
The stars in constellations are imaginarily linked together to form various images of an object, an animal, or a person in the sky. For instance, the Aquila constellation resembles an eagle. The brightest star in this constellation is the Altair, a white star that is seventeen light-years away from Earth. On the other hand, Scorpius represents a scorpion wherein three bright forms form its head while its tail curves away. The brightest star in Scorpius is Antares, which is located in its middle body.
Some of the animal constellations are Capricorn, Aquila, and Scorpius.
Mythology
Other well-known constellations are named based on Greek mythology. For instance, Andromeda is named after the princess of Ethiopia.
In this image, the constellation Andromeda is named after the princess of Ethiopia.
The brightest star present in this constellation is the Alpha Andromedae or Alpheratz, a binary star and a part of the Pegasus constellation. Another distinct characteristic of the Andromeda constellation is the different galaxies or star systems that lie on it.
Orion, on the other hand, is named after Orion, the hunter in Greek mythology. The two brightest stars in this constellation are Rigel, a bluish-white supergiant, and Betelgeuse, a red supergiant.
Other popular constellations are the Ursa Major, which means “The Great Bear,” and its smaller counterpart called the Ursa Minor or “The Little Bear.” What makes these constellations popular are the smaller patterns of stars within them. These smaller patterns are known as asterisms. For instance, the Big Dipper, which is composed of seven stars, is found in the Ursa Major, while the Little Dipper is present in the Ursa Minor. The North Star or Polaris is found in the Little Dipper.
Here are some of the popular constellations:
Where Can Constellations be Found?
Just like Earth, the celestial sphere is divided into North and South. Some constellations are only seen in the Northern Hemisphere, while some are seen in the Southern Hemisphere only. There are some constellations that can be seen in both North and South Hemispheres, particularly those that lie on the equatorial part of the celestial sphere. Orion is an example of a constellation that can be seen in both the Northern and Southern Hemispheres.
Constellations are found in the northern and southern hemispheres.
The constellations seen in the night sky are shifting very slowly. This is due to the movement of Earth on its axis. Earth rotates on its axis from west to east, which is also the reason why the stars seem to rise from the east. Aside from rotation, Earth also revolves or moves around Sun. This movement results in the changing position of Earth in space. As Earth continues to move through space, different sets of constellations are observed. This is why some constellations may only be seen at a particular time of the year. For example, constellations like Aquila, Hercules, and Sagittarius are often seen in June, July, and August. These constellations are referred to as summer constellations since they are seen during summertime. Other groups of constellations are seen in winter, spring, and autumn.
There are some constellations that are seen year-round, meaning they do not set at all. They are known as circumpolar constellations. These groups of stars surround the Polaris or the Northern Star. Polaris is just right above the axis of Earth in reference to the celestial sphere. Since it is directly above Earth’s axis, it does not seem to move while the stars surrounding it are moving. Polaris can only be seen in the Northern Hemisphere. This star is part of the asterism, Little Dipper, which is part of the Ursa Minor constellation. Other northern circumpolar constellations are Ursa Major, Draco, Cassiopeia, and Cepheus. On the other hand, the southern circumpolar constellations include Centaurus, Carina, and Southern Cross. The constellation Centaurus has Alpha Centauri, the third brightest star in the night sky and the second-closest star to the Sun.
Constellations are found in the northern and southern circumpolar sky
Importance of Constellations
The discovery of constellations has led to various opportunities to study heavenly bodies. Early astronomers look at the sky to observe the various stars and discover what is even beyond those stars. Now that the sky is divided into regions due to the boundaries formed by different constellations, it is now easier to locate objects in the sky. This also makes the exploration of what is beyond those stars easier for modern astronomers.
In the past, when calendars were not yet available, farmers relied on the stars to tell the time of the year. Since farmers noticed that stars are constantly shifting, they have devised a way to identify common constellations and use them as a guide in telling the season. This helps them identify what crops are best to plant during a certain period of the year or when they could have a bountiful harvest. In this modern day, wherein calendars are readily available, farmers do not rely on the constellations to plan their agriculture. However, some traditional farmers still observe the constellations as they never fail to tell the year’s season.
Constellations played an important role in navigation too. Early navigators used the Polaris as their point of reference when they traveled. To find Polaris, they usually locate the Ursa Major, Ursa Minor, or Cassiopeia constellations first as they are adjacent to one another. Once they have located the Polaris, they can now determine their latitude based on how far or near the Northern star is to them. To this date, locating the Polaris is beneficial to those who are traveling or stargazing.
The moon and stars seen in the sky are often associated with gods and goddesses. Many people in the early times believe that they were placed in a very high position as they possess significant powers. The supernatural stories about the moon and stars are being passed on from one generation to another in the form of myths. Myths are traditional or legendary stories that explain the origin of something, without any proven basis. What are the different myths about the moon and stars?
Myth About the Constellations
Remember that some names of constellations were derived from Greek mythology. For example, the constellation Andromeda was named after the princess of Ethiopia, the daughter of Cepheus and Cassiopeia. Her mother, Cassiopeia is a conceited woman who always bragged that she was the most beautiful among the other gods. Neptune got mad and sent a sea monster to attack the Ethiopian coast. In order to appease Neptune, Cassiopeia has to sacrifice her daughter Andromeda to the monster. Thus, they chained Andromeda on a rock that could be easily reached by the sea monster.
The hero Perseus saw what happened. He talked to the parents of Andromeda that he will save the princess only if they will allow him to marry her. Andromeda’s parents agreed to the condition given by Perseus so he killed the sea monster and freed the princess. The constellation Andromeda resembles a figure of a woman with outstretched arms with chained wrists. Perseus, who played a significant role in the story of Andromeda, has his own myth on how he appears in the sky. Ancient people believe that the image formed by this constellation is a man with a sword on one hand and the head of a lady on the other hand. The lady is said to be Medusa, a female monster with snake hair, whom he defeated in one of his fights.
Another constellation is named after a great hero in Greek mythology, Hercules. As a fighter, he has won many battles, including the fight with Hydra, a poisonous monster that can regenerate its head into two once cut off. In the sky, Hercules appears to be a bit kneeling while holding his club. Hercules is one of the biggest constellations but not as bright as the others. Ancient people believe that the “darkness” of the group of stars somehow represents the dim personality of Hercules as a warrior.
Myths About Sun and Moon
Aside from myths pertaining to constellations, there are some myths about the moon too. The moon is said to be shrouded in mystery, and a lot of stories from the Philippines and other countries surround it.
Stories from Other Countries
The full moon in January is referred to as Wolf Moon due to the howling of the pack of wolves at this certain period. This story is of native American origin. Another myth about the moon came from the Inuit people of Greenland. The name of their moon god is Anningan, who continually chases his sister Malina, the sun goddess after a huge quarrel. Since the chase is persistent, he forgets to eat, which makes him thinner. This symbolically explains the phases of the moon. On the other hand, Malina wants to stay away from his brother, which is why they rise and set at different times.
Stories from the Philippines
There are also some local myths about the moon and the stars. The famous one is about Maria, a young pretty girl with long, silky, black hair. Maria lives in a small town in the middle of a rice field. Each day, she uses her crescent-shaped comb to brush her hair and adorn it with pearls and jewels. Her neighbors admire her long, silky, black hair which she puts much time in taking care of. One day, she was pounding rice grains by using a big mortar and pestle. While doing so, her mother noticed that she was still holding the comb and her hair was adorned with pearls and jewels. She was scolded and asked to put aside those things while working. She removed her accessories and hung them in the sky above her. She continued her work and tried to pound the rice grains as fast as she can so she can finish early. Maria did not notice that as she pounds, she is hitting the sky, which causes it to go higher. The sky moved up all the way high together with her crescent-shaped comb, pearls, and jewels. Eventually, the comb became the moon and the pearls and jewels became the stars in the sky.
Another local myth is about the moon and the sun. According to the story, in the beginning, there was no darkness. This is because Adlaw (Sun) and Bulan (Moon) are happily married. They have plenty of offspring whom they called Tala and Bituin (stars). One day, Adlaw and Bulan had a great fight that caused them to part ways. When they separated, Tala and Bituin joined Bulan, and Adlaw was left alone. From then on, Adlaw is the only one who gives light during daytime, while Bulan, together with Tala and Bitui,n provides light during nighttime.
Debunking Myths
There are plenty of myths all over the world. The question is, how can you stop people from believing them? As a student who studies science, it is important that you know how to debunk or disprove myths. Science is a systematically organized body of knowledge that is attained through research and experiments. Therefore, science is based on facts and can provide pieces of evidence to disprove a certain myth.
There are different ways to debunk a myth. First, make sure you are very much aware of the topic that is related to the myth given. For example, the story of Anningan and Malina symbolically explains the phases of the moon. You can start debugging this myth by providing explanations on Earth’s revolution around the sun. Then, demonstrate using models of Earth, Moon, and flashlight (as our Sun) to show that the amount of light illuminating the moon changes once it moves together with Earth. By doing so, you can provide pieces of evidence on why the moon has different phases. This will disprove the myth that tells about the moon getting thinner every month due to its chase with the sun.