LUCAS TAN 

Core:

Nuclear fusion reactions: Hydrogen photon undergo a series of fusion reactions, converting into helium, releasing large amounts of energy (gamma rays)

Hottest part of the sun: Temperatures in the core reach extreme levels (<15 million celcius)

Gravitational pressure: Tremendous (high density)

Radiation Zone:

Extends to about 70% of the sun's radius

Energy generated is transported outward via the slow movement of photons (electromagnetic radiation). Photons created bounce between ionised atoms, taking thousands to millions of years to make their way towards the surface. 

Temperature decreases as it is further away from the core

Convection Zone:

Energy transport occurs through the movement of plasma in large convective cells. Hot plasma rises from the deeper layers, carrying energy with it. Cooler plasma descends to help transfer energy more rapidly

Temperature decreases as it is further away from the core, causing the appearance of granules and supergranules on the Sun's surface, which is visible in high-resolution images.

Sunspots:

Temporary phenomena on the photosphere.

Appears as dark.

Intense magnetic activity inhibits the upwelling of hot plasma, reducing temperatures in sunspot regions.

Cyclical pattern: The solar cycle averages about 11 years. The number of sunspots reaches a maximum during the solar maximum and decreases during the solar cycle.

Solar flares:

Sudden, intense releases of energy

Caused by the reconfiguration of magnetic fields

During a solar flare, charged particles are accelerated to high energies which can be ejected into space, contributing to space weather and potential impacts on Earth's magnetosphere. 

Emits various forms of electromagnetic radiation, including X-rays and ultraviolet light

Solar prominences:

Large, looping structures of relatively cool and dense plasma.

Extend from the Sun's surface into the outer atmosphere.

Near sunspot regions and are held in place by magnetic fields.

Noticeable during a solar eclipse when the moon blocks the bright solar disk to reveal the outer regions of the Sun.

Change rapidly and some may erupt into space, releasing material into the solar wind.

Solar prominences VS Solar flares:

Anchored to the Sun VS Travels through space

The aftermath of solar flares VS Causes of solar prominence

Plasma loops that connect 2 sunspots VS Eruptions of highly charged particles

Rotation:

Full rotation on its axis is about 27 days

Equator rotates faster than the poles due to the Sun's gaseous compositions and Equatorial Differential Rotation

Aurora bealius:

Solar flares trigger magnetic storms and the particles in them seep through the Earth's magnetosphere to cause substorms

The fast moving particles collide with nitrogen and oxygen in the substorms, causing the nitrogen and oxygen particles to glow, forming the Aurora Borealis

Earth:

Causes: Weather patterns, ocean currents, seasons, climate

Sustains life through its warmth and sunlight (photosynthesis and keeping Earth warm)

Formation:

From a giant, spinning cloud of gas and dust called the solar nebula. It collapsed under its own gravity, spinning faster and flattening into a disk. Most of its material was pulled towards the centre to form the Sun (99.8% of our solar system's mass)

It will eventually run out of energy and expand into a red giant star, potential engulfing Mercury, Venus and possibly Earth

Currently a little less than halfway through its lifetime with an estimated 5 billion years remaining before it runs out of energy and becomes a white dwarf

Reflection: Learnt about astro

Week 1 (2 March 2022): 

We learned about two different telescopes, which are retracting and reflecting. We also had an Astronomy Club Orientation Programme :D

Week 2 (9 March 2022): Pls give us more time to type :(

Epochs: Plank, Grand Unification, Inflationary, Quark and Hadron, Photon, and Recombination

Plank: Gravity behaves according to quantum mechanics and the laws of physics may not work on gravity.

Grand Unification: Gravity became the impostor (sus) and left the alliance. Only 3 of the four fundamental forces were unified: 

Strong nuclear force, weak nuclear force and electromagnetic force.

Inflationary, Quark, Hadron: Space becomes larger, by order of 10^26, over a time of 10^-36 to 10^-32 seconds, cooling down the Universe by a lot, resulting in the remaining three forces taking up the present forms. However, it was still too hot for the quarks to form hadrons. When the temperatures drop enough, the quarks become tin, forming hadrons. 

Photon: Then, the Universe became cool enough for electrons, protons and neutrons to form. Protons and neutrons combine to form nuclei. However, electrons did not bind to nuclei, electrons and photons.

Recombination Epoch: Electrons and Nuclei from atoms and the Universe becomes transparent to photons. The Cosmic Microwave background radiation originates from this epoch.

After the Dark Ages: The Universe becomes transparent, allowing light to travel long distances. However, there were very few light sources. The Universe contained only hydrogen gas and background radiation left over from the Big Bang. Over time, gravity filled the densest regions of hydrogen gas into compact clouds which then collapsed to form the first stars.

After the Dark Ages (The Stars): These stars were classified as Population III stars. Distinctively, they virtually had no metals. They are incredibly luminous and highly massive, between a few hundred to thousand solar masses.

Matter: The birth of stars accelerated as the Universe left the dark ages. Denser lumps of matter around the Universe gave rise to the rapid formation of stars as gravity caused them to clump together. The further clumping of protostars was caused by gravity, forming protogalaxies that later became Universes.

Galaxy Mergers: Gravity eventually caused galaxies to merge, forming more giant galaxies. Most of the early large galaxies were spirals, but merging caused them to become more elliptical. Galaxies then become galaxy clusters. This process can trigger the intensive formation of stars.

Start of Solar System: The Sun and planets formed together 4.6 billion years ago from a cloud of gas and dust called a solar nebula. The Sun formed in the centre and the planets formed in a tin disk, orbiting the Sun. Then, the Sun ignited, causing a strong solar wind.

Planets: Before the Sun ignited, planetesimals were formed from small bits of dust and gas clumping together amidst the accretion disk. They then collided with each other to form larger plants due to gravity. 

Cooling Down: Many collisions occurred during this process as space debris rained down on larger objects, creating much harm. As the amount of stray debris reduced, the collision rate decreased, decreasing the heat generated. The planets then cooled down from large molten rock to what it is today.

Starting Afresh?: Eventually, a collision between young Earth and a smaller planetesimal affected the orbits of the more prominent objects way earlier during the formation process of the Earth.

The Birth of Moons (Earth’s Moon): The moon was likely formed after a Mars-sized body, Thea, collided with Earth several billion years ago. The resulting debris from both Earth and the impactor accumulated to form our natural satellite. Initially, it was molten.

Types of Black Holes: Stellar Black Holes are black holes with millions of solar masses caused by the merging of black holes, absorbing other matter and objects. Primordial Black Holes are small black holes that might have been created during the Big Bang.

Stellar Black Holes: A stellar black hole can be formed if a neutron star absorbs enough material from a nearby binary star or other object, causing the neutron star to collapse and become a black hole. They can also be formed directly. They can be formed as long as cores/remains of collapsed sets are more than five solar masses, causing an escape velocity greater than the speed of light. The stars that formed the stellar black holes must be larger than 20 solar masses for that condition to occur.

Formation of Early Supermassive Black Holes: Clouds of gas in the early Universe have variations in density and those that are super dense created black holes immediately. Prominent stars formed during the early stage of the Universe created supermassive black holes when they died. The rapid formation of galaxies in the early stage of the Universe fuelled black holes to grow to an even larger size.

Low Mass Stars: Low Mass Stars are tiny and usually comprised of red dwarfs. They fuse hydrogen into helium. During helium 

fusion, stars with more than 25% solar masses will expand into a red giant. Eventually, it will shed most of its mass as a nebula and turn into a white dwarf. Stars with less than 25% solar masses cannot fuse helium so they would collapse into a white dwarf. However, it can take trillions of years to cool down.

Nuclear Fusion: It is when two different molecules collide with each other with intense forces to the point when they fuse, releasing massive amounts of energy.

Intermediate Mass Stars: They are heavier but not heavy enough for massive explosions. They can fuse helium into heavier elements such as carbon and oxygen, shortening its life span. They also would collapse into a white dwarf, similar to Low Mass Stars. 

White Dwarfs: They are the remains of Intermediate Mass Stars. They are highly dense and have the mass of about the Sun’s while having the volume of about the Earth’s. This is because when it collapses on itself, all the remaining mass is compressed into the star’s core, thus making it dense and heavy.

High mass Stars: High Mass Stars are the most extreme stars in the Universe. They are 10x to 70x the mass of our Sun, enough for them to implode and cause massive explosions.

Supernovas (Type II): Their cores are usually obliterated or turned into other things during this process. Hence, white dwarfs are very uncommon to appear. A high-mass star has plenty of nuclear energy in it to counter its own gravity. However, as the high-mass star runs out of fuel, there is not enough nuclear energy to counter its own weight so it collapses on itself.

Supernovas (Type Ia): It involves one white dwarf orbiting another star, a white dwarf or a bigger star. Usually, the white dwarf accumulates matter from the other star until a reaction, “Runaway Nuclear Reaction”, ignites, leading to the white dwarf exploding. The same explosion can also be produced from 2 white dwarfs colliding.

Neutron Stars: A neutron star is one of the things a massive star becomes after exploding. When a star collapses on itself, the atoms in the core get compressed to the point where the electrons and protons start to be crushed together into neutrons, forming a neutron star that spins really fast.

Pulsars: Pulsars are the most common form of a neutron star, emitting pulses of intense energy at intervals while also having powerful magnetic fields which shoot out particles from each pole.

Magnetars: A magnetar is another type of neutron star. In a typical magnetar, the magnetic field is about 1000x stronger. In a magnetar, with its vast magnetic field, movements in the crust cause the neutron stars to release a vast amount of energy in the form of electromagnetic radiation.

Blackholes 2: When a star collapses, an imaginary surface, called the “event horizon”, forms the point where light cannot escape from the gravity of the black hole. According to Einstein’s theory of relativity, time starts to slow down under the influence of strong gravitational forces. At the event horizon, the star’s surface will stop moving and can no longer collapse further.

Degenerate Era: As Stars explode like fireworks in the sky, the planets that reside near their stars will get vapourised. As a white dwarf pulls material from a companion star, the temperature decreases. A black hole “survives” by pulling objects into its event horizon. In the end, the black hole lights up the Universe for the last time.

Proton decay: Proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles such as positron and pion. It is hypothetical.

The Death of the Universe: When the expansion of the Universe eventually reverses and the universe re-collapses, it ultimately causes the cosmic scale factor to be zero. This will happen when all the heat and energy are evenly spread across the Universe. Then, the Universe, atoms, subatomic particles and even spacetime itself are progressively torn apart by the expansion of the Universe.

Week 4 (23 March 2022): Extra-terrestrial: Habitability, Fermi-Paradox, Communication, Seager Equation

Fermi-Paradox (Named after Physician Enrico Fermi): It is the apparent contradiction of the lack of evidence and high probability estimates for the existence of extra-terrestrial life.

The Great Filter: An “evolutionary path” in which intelligent life would have to take before discovering other colonies of extraterrestrial origin or us. The absence of intelligent life in space would mean that one of the steps is improbable to work. If one step fails, the said intelligent life will start from scratch.

The Drake Equation: N = R* × FP × ne × fl × fi × FC × L

N is the number of civilisations currently transmitting signals, depending on seven factors:

R* is the yearly formation rate of stars hospitable to planets where life could develop,

fp is the fraction of those stars with planets,

ne is the number of planets per solar system with conditions suitable for life,

fl is the fraction of planets suitable for life on which life actually appears,

fi is the fraction of planets with life on which intelligent life emerges,

FC is the fraction of planets with intelligent life that develops technologies such as radio transmissions that we could detect,

L is the average length of time in years that civilisations produce such signs.

Communication; Technosignatures: If intelligent life were advanced enough, we would find megastructures acting like lighthouses.

Week 5 (30 March 2022): Black Holes

Black Hole Sighting: We cannot see a black hole as its strong gravity pulls all the surrounding light to the centre of the black hole. 

However, astronomers observe the presence of a black hole by its effects on its surroundings.

Black Hole Size and Mass: A black hole’s size and mass can vary greatly. The smallest black holes can be as small as one atom but they have a mass of a large mountain. The largest black holes can be as big as a few million Earths combined and they have a mass equal to around 4 million Suns.

Types of Black Holes: There are four types of black holes: stellar-mass, intermediate, supermassive and miniature black holes.

Stellar-Mass Black Holes: They are the most common black holes, ranging from 5x to 10x the mass of the Sun.

Intermediate Black Holes: They are significantly more massive than a stellar-mass black hole. However, they have less mass than supermassive black holes. They range from 100x to 1,000,000x more massive than the Sun.

Supermassive Black Holes: They are the largest type of black holes, ranging from 1,000,000x to 10,000,000,000x the mass of our Sun.

Miniature Black Holes: They are hypothetical tiny black holes. Their size is equal to or above 22.1μg (about 1/1,000,000 of a gram).

The Creation of Stellar-Mass Black Holes: When the centre of a massive star falls upon itself (collapses), the process causes a supernova (an exploding star that blasts part of itself into space) (stellar-mass black hole).

The Creation of Intermediate Black Holes: They are too massive to be formed by the collapse of a single star. One theory as to how they are formed is that stellar-mass black holes gravitationally attract other stellar-mass black holes or compact objects. The merging of stellar-mass black holes and compact objects form them.

The Creation of Supermassive Black Holes: Their formation is still unconfirmed. Some have suggested that they form from/due to the collapse of massive gas clouds during the early stages of the galaxy’s formation.

The Creation of Miniature Black Holes: Soon after the creation of the Universe, they formed. (most widely accepted hypothesis for their creation) 

The Photography of Black Holes (Using an Event Horizon Telescope [EHT]): Use it to capture an image of a black hole. Its degree of precision makes it able to resolve objects about 4000 times better than the Hubble Space telescope.

The Photography of Black Holes (Using a Very Long Baseline Interferometry): Creating an array of smaller telescopes that can be synchronised to focus on the same object simultaneously and act as a giant virtual telescope.

Extra Infomation: There are six main parts of a black hole but two more unmentioned aspects of it.

The Event Horizon: It is infamously known as the “point of no return”. Once any matter is inside it, the matter will fall into its centre. Its strong gravity squishes to an extremely tiny volume with an enormous density.

The Singularity: It is the extremely tiny volume with an enormous density. It is so tiny that it essentially has an infinite density. Hence, it is likely that the laws of physics break down at the singularity.

Spaghettification: The Singularity is found at the centre of a black hole and it exerts a strong gravitational force on any matter that falls in. This process is called “Spaghettification”.

White Holes: They are the polar opposite of black holes. They also contain a singularity but they operate in reverse to black holes. No matter can enter the centre of a white hole and any matter inside it will get rejected immediately.

Wormholes: White and black holes are connected as since they would exist in separate places in space, a wormhole would bridge their two ends. A wormhole described Einstein’s theory of relativity. However, wormholes are super unstable. If a matter dropped towards the centre of a white hole, the matter would never reach the centre of a white hole since nothing can enter a white hole. When a particle enters that white hole, the white hole’s system’s energy increases to infinity and the white hole explodes.

The Shape of Wormholes: The entrance of a wormhole would be a sphere, like the surface of a planet. If one looks into it, he/she will see the light coming in from the other side. Its tunnel could be of any length. While travelling through its tunnel, he/she would see distorted views of the region of the Universe he/she came from and the region he/she was travelling to.

Time Travelling Using Wormholes: A wormhole can also act as a time machine. Special relativity dictates that moving clocks run slowly. If scientists could somehow construct a wormhole, initially, the two ends would be synchronised in time. However, if one end was then accelerated to nearly the speed of light, it would start to lag behind the other end. The two entrances could then be brought together, but one of them will be in the past of the other.

Hawking Radiation Glossary: Quantum fluctuations - the temporary random change in the amount of energy in a point in space Annihilation - the conversion of matter into energy

The Evaporation of Black Holes: It is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole’s horizon.

Week 7: Kerbal Space Program (KSB) (Space Simulator): https://docs.google.com/presentation/d/1Jjgedmv78T9hXj7qvJVxUDaR-s0SfUb9Aw8-T4JtZJA/edit?ddrp=1#slide=id.gca5d31f1e3_1_0

Week 8: Rover

The purpose of a Rover: A Rover’s main objective is to determine the geographical processes that shaped the terrain of the region, study the composition of rock and soil to find evidence of water (if there is water), and study the environmental conditions that existed when liquid water was present.

How is a Rover designed?: A Rover is a lander spacecraft designed to have soft landings to keep its machinery functioning in order to employ parachutes to have low impact terminal velocity. Since signals from Earth take minutes to reach Mars, a Rover at Mars has to be able to traverse the terrain autonomously. Rovers have appendages in their design to aid them with their mission. An appendage is a mast for the sensors to give the rover a human-scale view. A Rover has “hands” to hold rock samples and various scientific instruments and drills to study fresh items. A Rover has two main sources of power, which are solar energy and nuclear energy. A Rover has solar panels that use the energy from the Sun to power lithium batteries. The solar panels only work during daytime and when the skies are clear. The solar panels produce solar energy. A Rover also uses another power source called “Multi-Mission Radioisotope Thermoelectric Generator” (MMRTG). Those power sources allow the Rover to receive a dependable flow of electricity using heat from a piece of plutonium that they carry. They use the piece to charge batteries, similar to solar panels.

MOXIE: The Mars Oxygen ISRU Experiment (MOXIE) is a tool that was brought with the Perseverance Rover to test the MOXIE on mars. As the name suggests, it is used to produce oxygen from the carbon dioxide from mar’s atmosphere.

RAT: The RAT is used to break open rocks. It was equipped onto the Spirit and Opportunity rovers.

RAD: The Radiation Assessment Detector (RAD) is to characterise the broad spectrum of radiation environment found inside the spacecraft during the cruise phase while on Mars. It was equipped only onto Curiosity.

The Spirit Rover: The Spirit Rover uses a different landing method from the Opportunity and Perseverance Rovers. It uses airbags to land on the surface on Mars and got stuck in a pit after falling into it.

The Perseverance Rover: The Perseverance Rover is fully powered by nuclear energy. It uses rockets and parachutes in combination to descend safely (7 Minutes of Terror). It has 2 movable arms, one under the ROver and one on the outside of it. The objective was to look for biological signs of life on Mars.

The Opportunity Rover: The Opportunity Rover is powered by 2 rechargeable lithium batteries in combination with solar cells. NASA declared its mission to be complete on 13 February, 2019.

The Curiosity Rover: The Curiosity Rover uses nuclear power, although not sustainable, lasts long enough for its objective to be completed. Its objective was to analyse Mars for life (until it dies).

7 Minutes of Terror: Essentially, the 7 minutes from the Perseverance Rover entering Mar’s atmosphere to the Rover touching down on the surface. It is all done automatically and the people in NASA were in utter distress during those 7 minutes.

Presence of water on Mars: During a mission, the Opportunity rover encountered hematite, which is a mineral found in water, in a crater it landed on, suggesting that water was present on Mars a long time ago.

Location which possibly supports life: The Spirit Rover found a place where the rocks were rich in minerals like magnesium and iron carbonates, as well as having a more neutral pH, many scientists believe that these conditions were hospitable and could have supported life on Mars.

Flowing water: The Opportunity Rover found bright-coloured veins of stuff in the rocks, which scientists believe to be flowing water.

Week 9: Learnt how to construct a good rocket. Done in Space Flight Simulator (SFS)

Week 10 (4 May 2022): 

Satellites: Intentional Artificial Satellites, Planetary Observation, Active & Passive Communication, Navigation, Telescopes, and Space Station and Crafts.

Satellites: Earth’s moon etc. They are used to send and receive signals continuously and applies to satellites orbiting other planets. 

A notable example of its use: Elon Musk using Starlink to provide internet to people in Ukraine.

Planetary Observation: Take pictures and record data about the planet they are orbiting. 

Planetary Observation for Earth: Environmental monitoring, meteorology and cartography.

Communication: Relays information across the curvature of Earth through radio signals. 

Multiple satellites work together to communicate. 

Navigation: Provide autonomous geo-spatial data and super accurate time synchronisation. Common Global Navigation Satellite Systems (GNSS): GPS, GLONASS and beidou

Telescopes: Observe distant astronomical objects. They are better because it avoids light pollution and other distortions that the ground telescopes face. It has an astronomical survey to map the whole sky.

Reflection:

Learnt about astronomy stuff and did an astronomy-related Kahoot.

Focused survey: focuses on ceratin objects and part of the sky.

Space station and crafts: Support human crew for extended periods of time. They are for scientific purposes such as to study the effects of spaceflight on the human body, as well as to provide a location to conduct a greater number and longer length of scientific studies than is possible on other space vehicles.

ISS: The international space station (ISS) is a modular space system in low earth orbit. It is a multinational collaborative project in five participating space agencies: NASA (USA), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). It was intended to be a laboratory, observatory and factory while providing transportation maintenance. However, not all of the uses envisioned in the initial memorandum have been realised.

New Horizons: New Horizons is a NASA mission to study the dwarf planet Pluto, its moons, and other objects in the Kuiper Belt, as well as was the first spacecraft to encounter Pluto. It carries a cylindrical radioisotope thermoelectric generator (a spare from the Cassini mission) that provided about 250 watts of power at launch.

Sputnik 1: It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the soviet space program. It orbited for three weeks before its batteries ran out. It also has four external radio antennas to broadcast radio pulses, making it a passive communication satellite (that is basically useless).

SMAP: The Soil Moisture Active Passive (SMAP) is a NASA environmental monitoring satellite launched on 31 January 2015 and detects soil moisture which provides invaluable information all across the globe.

Cassini-Huygens: The Cassini-Huygens space-research mission is a collaboration among NASA, ESA and ASI to send a space probe to study the planet Saturn and its system, including its ring and natural satellites. Its objective is to determine the 3D structure and dynamic behaviour of the rings of Saturn.

Disposal (Satellites outside Earth): Deorbiting is similar to graveyard orbiting. 

Controlled entry: Launch the satellite to the atmosphere of the planet for them to burn up, like in LEO for Earth satellites.

Week 11 (11 May 2022): NIL

Week 12 (18 May 2022): Constellations

Glossary (NGC): “NGC” stands for “New General Catalogue”. The catalogue refers to an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888.

Constellations’ purposes: Constellations are useful as they help stargazers and astronomers recognise specific stars in the night sky. Constellations are also used for navigation and to help sailors travel across oceans, especially in ancient times. Once you find Ursa Major, you can easily spot the Northern Star (Polaris). By using the height of the Northern Star, one can figure out one’s latitude. People also used constellations to tell the difference in the colours and constellations were also used to group stars.

Asterisms: Asterisms are patterns of stars with shapes and sizes that can range from the very simple, containing just a few stars, to the larger and more complex, with some of these arrangements covering large regions of the night sky. Stars within an asterism are usually of similar brightness to one another and might range from bright and visible to the naked eye, or distinguishable with a telescope.

Winter Triangle: The Winter Triangle asterism, also known as the Great Southern Triangle, is a prominent asterism formed by Sirius, Betelgeuse and Procyon, which are the primary stars in the 3 winter constellations of Canis Major, Orion, and Canis Minor. The Winter Triangle is a prominent asterism in the night sky in the northern hemisphere during the winter months, from December to March. The 3 stars that form the Winter triangle are among the brightest stars in the night sky. The Winer triangle stats are Sirius (the brightest star in the night sky), Betelgeuse and Procyon. Betelguese, the star marking the left shoulder of Orion, is just above Alnitak, the easternmost star of the Belt. Sirius can be found by following a line formed by the Belt stars to the southeast, while Procyon lies to the upper left of Sirius. 

Ways to track other deep sky objects with the winter triangle: The Heart-Shaped Cluster (Messier 50), The Cone Nebula, and The Christmas Tree Cluster in the Monoceros constellation can all be tracked using The Winter Triangle.

Reflection: We learned about constellations and there was a fun Kahoot. 

How can it be improved: Change the presenter. (jk)

Week 18 (29 June 2022): 

1. Stretching and squeezing of spacetime.

2. Ligo, a large-scale observatory that measures gravitational waves.

3. Gravitational waves are produced by cataclysmic events.

4. Enceladus is the sixth-largest moon of Saturn and has water-rich plumes and cryovolcanoes that shoot geysers.

5. Sounds on Mars are slower than sounds on Earth due to the density and the composition of their atmosphere.

6. Kepler-452b is an exoplanet that has the possibility of life.

7. Magnetars are pulsars with an unreliable and erratic burst of radiation.

8. The first image of a black hole captured was a super-massive black hole at the centre of messier 87

9. Usually, black holes cannot be seen as they absorb light.

10. Discovered by Gaia

11. Neutron stars have 10 to 25 solar masses and collapse when stars run out of fuel.

12. Kahoot was rigged. Learnt about planets and stars. Lesson was okay I guess...

Week 19 (6 July 2022): 

Reflection: Was no Kahoot but had fun activities. Learnt about food. Lesson was okay I guess...

Week 21 (20 July 2022):

Reflection: Learnt about stars' life cycles. The first astro-related kahoot I played that was not rigged at all. Can work on adding more presenters. 

Week 22 (27 July 2022):

Supernova: The burning process will continuously burn till it can no longer be fused. Gravity tips over its thermal pressure and causes a core collapse.

Reflections: Kahoot was long. Only one presenter. Revised about previous lesson. Lesson was about astronomy.

I learned about the evolution of stars and their future. I have no questions about it and I found it very interesting. The Kahoot was hard. The part about the stars going around a point and getting compressed before it gets spits out shocked me.

28 August 2022: The topic was interesting but there was no game to sum it up (I like games :D) and the slides went to waste as the presenter did not need to present some of the slides. The presenter was ok but the other one apparated. I learned about deep-space objects.

14 Sep 2022: I learned about the LEAPS 2.0 system and signed up for the Dome Program (Competition) for my CCA Service marks so I won't fail my CCA.

11 January 2023: I downloaded KSP (Kerbal Space Program) and learnt how to use it.

19 April 2023: Found my sites back. :)

Anyways I learnt about sec 1 stuff (that i already learnt)

Brown drawfs:

• They are known as failures and occur due to insufficient mass of hydrogen reserves. A brown drawf is technically dead, and more of a cold planet.

• They are too small to sustain hydrogen fusion.

• They have a mass between the most massive gas giant planets (e.g. Jupiter).

• Hence, Jupiter is a failure.

Red supergiants:

• Forms when stars start to die.

• Its core collapses in on itself.

• Its increasingly hot core pushes the outer layers of the stars outwards.

• It expands and cools, transforming into a red giant.

• It is roughly 0.3 to 8 solar masses.

• It has a surface temperature of <= 5000ºK

Type II supernova:

• Occurs when a massive star dies (when its nucelar fuel is exhausted).

Supernova remnants:

• A supernova remnant is a structure that remains after a massive star has exploded as a supernova. 

• The remnant consists of a central region of highly compressed and heated material, surrounded by an expandind shell of gas and dust.

• Supernova remnants can be observed across the electromagnetic spectrum, from radio waves to X-rays

• Classified into "shell-type" and "crab-type".

• Composite remnants are a cross of both.

• Supernova remnants are important to us because they impact the ecology of the Milky Way. Without these, Earth would not have any stuff...

(Shell-type):

• The shockwave of the explosion ploughs through space. It heats and stirs up any interseallar material.

• There is more hot gas in our line of sight at the edges than when we look through the middle.

• Astronomers call this phenomenon limb brightening.

• They are ring-liked shaped.

(Crab-type):

• A.k.a. pulsar wind nebulae or plerions.

• They look more like a blob rather than a ring.

• It is filled with electrons that are flung out from a pulsar in the middle.

• Its electrons interact with its magnetic field.

(Composite thermal):

• Appear shell type in radio waveband.

• Appear crab-like in X-rays.

• Unlike true crab-types, they have spectral lines indicative of hot gas.

(Black holes):

• Invisible to the naked eye since you can't spot a black object in pure black (racist).

• They can be detected and proven to exist.

• The first direct image of a black hole and its vicinity was published, following observations made.

• They die due to Hawking Radiation in a googol year for supermassive black holes.

(Neutron stars):

• It is a collapsed core of a massive star.

• It is so compact that its density is equivalent to Mount Everest in a coffee cup.

• It contains sub-types.

• It undergoes a process when it rotates (spinning up and down).

• They can also undergo a star reaction.

(Pulsars):

• Rapidly spinning neutrons stars.

• Rotate very rapidly, with periods ranging from a few milliseconds to several seconds.

• The fastest known pulsar is very fast.

(Magnetars):

• It has an extreme magnetic field that can cause rapid rotation and generate powerful bursts of X-rays and gamma rays detected on Earth. Their magnetic fields can distort and twist.

• Magnetar bursts can be among the most energetic events in the universe, releasing as much energy in a fraction of a second as the sun does in 100,000 years.

(Planetary Nebulas):

• It is a type of astronomical object that forms when a low-mass to intermediate-mass star (like the Sun) exhausts its nuclear fuel and begins to shed its outer layers.

• Despite its name, it has nothing to do with planets; the term comes from their resemblance to the greenish disks of Uranus and Neptune as seen through early telescopes.

(White Dwarfs):

• It is an emission shell of ionised gas and is a bit of a misnomer due to inaccurate findings during the 1780s.

• It signifies the end of a typical star's life cycle.

• It is made out of something with unbound nuclei and electrons.

• Around the size of the Moon.

(Black Dwarfs):

• It is a hypothetical object that results from the cooling and fading of a white dwarf star.

• It is not currently observable because the universe is not old enough for any white dwarf to have cooled to this state.

• Its existence is purely theoretical, but they are thought to be the ultimate fate of most stars in the Universe.

• It is made of iron. 

reflecton

Learnt about solar weather as well as solar flares and CMEs. Also learnt on how they impacted earth and why we need to take action to prevent it. The presentation was quite engaging with many visuals and pictures, as well as being generally interactive. It can be improved by having more time for QnA. 

Exploration

• past missions:

  •  voyager 1 and 2 (flyby of all 4 giant planets)

  • galileo: jupiter orbiter

  • cassini: detailed study of saturn

  • juno: focused on jupiter's interior and magnetic field

• Discoveries

  • ring systems atmospheric storms, moons with potential habitability

• future missions: 

  • europa clipper (to study Jupiter's moon Europa)

  • Dragonfly (Titan exploration)

Reflection:

Today we had a hands on activity using universe sandbox. We had to create a planet that is habitable. It was surprisingly challenging for what seemed like a simple task. It is interesting to see how minute changes in the universe is makes such large differences. 

Reflection:

Learnt about astronomy stuff and did an astronomy-related Kahoot.

Reflection:

pro ksp (learnt about ksp)

Reflection:

Learnt about astronomy stuff and other stuff.

Reflection:

Water rockets without water, telescoping without telescoping.

Reflection: Learnt about gravitational tides, eclipses etc. from Mr R's presentation. Learnt about astronomical times (UTC, TT etc.) from Gavriel's presentation. I can apply this by doing astronomy. I can also use KSP. I can also find time of different time units like Julian Day etc. so that i can know times better. I also managed to get first in kahoot.

Reflection: Learnt about radios. and radio frequency 

Did foxhunting and found all the radios by using cubicSDR (the GOAT of astro)

Reflection: passed test so i'm the goat. obv cca gets revamped just when i bout to leave

Reflection:

I learnt about astronomy forces like centrufugal force and angular motion. I also watched kerzegat video. I also learnt about supernova. I will apply this by being a centrufugal force.



Reflection: I have garnered knowledge pertaining to Kerbal Space Program, astronomy, and Universal Sandbox, the latter of which I believe could benefit from enhancements. Despite the perceived shortcomings of a certain individual named Sanath, I found entertainment in utilizing Kerbal Space Program and now express a desire to further expand my learning of this particular application.

Reflection: I have acquired knowledge pertaining to stellar nebulae, and subsequently delivered an elaborate presentation incorporating intricate coding and circuitry. The selection of the subject matter was serendipitously determined by Sanath Warad or another EXCO. I intend to implement the concepts learned by embodying the attributes of a stellar nebula.

Reflection:

Learnt well about astronomy. 

Reflection:

KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. KSP fun. Weather is bad.

Reflection:

Sec 4s presented so the lessons were overall much better. Telescope good. nil.

(7 February 2024): General theory of relativity

Why is general relativity important: It provides a more accurate detail.

General relativity vs special relativity: General relativity is x10 more important than special relativity as it describes gravity as the curvature of spacetime caused by mass and energy, offering a broader understanding of the gravitational interaction in the presence of all forms of matter of energy.

General relativity: Spacetime merges space and time into a flexible 4D continuum that can be warped by matter and energy causing curvature visible through effects like gravitational bending of light.

Time dilation: It occurs when the observer's time appears to pass at a different rate relative to another observer in a different gravitational field or moving at a different velocity.  Higher gravitational fields or higher relative velocities result in slower time passage.

Redshift: A phenomenon that makes distant celestial objects like galaxies and nebulas appear red due to the "stretching" of lights as gravitational waves of large objects stretch the light that passes near them, causing the wavelengths of the light to become longer and appear redder. 

Lorentz factor: describes how time and space are affected by relative motion

Einstein field equations: describes the curvature of spacetime in the presence of matter and energy

Friedmann equations: describes the evolution of the universe

Schwarzschild metric: describes the geometry of a spacetime in the presence of a non-rotating, spherically symmetric mass

Waves detection: used to model the expansion of the universe, understand the behaviour of galaxies and explore the nature of dark matter and dark energy

Reflection: (P) The CCA was better as Sec 4s presented instead of the incompetent Sec 3s apart from Advaith and Gavriel. Learnt about general relativity and its lore. (E) For example, I went to the front with Advaith and his friend to show Einstein's theory of general relativity. (E) Hence, I managed to learn a lot about general relativity besides taking notes. The videos also allowed me to visualise the other theories better as well. (C) Since the previous CCA sessions that were hosted by the Sec 3s were badly done, this further contributed to my undeniable preference for the expert methods that Sec 4s used. (L) Therefore, I felt that today's CCA presentation was excellent as it was able to allow me to understand general relativity a lot more than before I attended this CCA session. (R) Hopefully, the Sec 3s will be able to improve, although the chance is basically none, and do better if they manage to become Sec 4s in the next year.

Hohmann Transfer: Elliptical orbit used to transfer between 2 circular orbits.

Reflection: KSP good. KSP better than presentation. Presentation about how rockets work, history of rockets, space race, rocket crashes, major stuff achieved in astronomy

Reflection: KSp good. Learnt about radios. Presentation about how radios work. Radio waves good.

Reflection: Many talks. Learnt about Kepler's 3 Laws. Astro good. Also learnt about how Kepler got his 3 Laws and his work on Mars (watched 2 vids on it). Sec 1s bad. Gavriel good. Many talks. Learnt about Kepler's 3 Laws. Astro good. Also learnt about how Kepler got his 3 Laws and his work on Mars. Sec 1s bad. Gavriel good. Many talks. Learnt about Kepler's 3 Laws. Astro good. Also learnt about how Kepler got his 3 Laws and his work on Mars. Sec 1s bad. Gavriel good.