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Astro 101 is your destination for learning about the basics of Astronomy, the oldest surviving branch of science.
Astro 101 is your destination for learning about the basics of Astronomy, the oldest surviving branch of science.
What is Astronomy?
What is Astronomy?
Astronomy is the study of the universe beyond Earth’s atmosphere. It includes everything from Planets, Stars and Galaxies to Pulsars, Magnetars and Supermassive Black holes! The Scope of Astronomy varies many order of magnitudes. To be an Astronomer, one uses the language of Mathematics and Physics to make inferences, observations and conclusions, which are then used to formulate postulates and theories. As a bonus, these theories could then be used to predict the future. Isn't it absolute awe inspiring that we mere humans could come up with models that could one day (Not yet) explains the WHOLE UNIVERSE?
If the terms you just read doesn't make sense to you, Perfect! This website is just the thing for you. It is designed to be beginner friendly, and it will aid you in understanding the basics of Astronomy, so you could equip yourself with the essential knowledge which can be used to delve into the specifics at your own pace later on.
The Earliest Signs
The Earliest Signs
The oldest recorded motions of the night sky made by humans is at Nabta Playa, which has been dated to roughly some 7000 years ago. The primitive stone circle could track the arrival of the Summer Solstice, which marks the day with the longest available daylight.
“This was the dawn of observational astronomy”- J. M. Malville
Classical and Post-Classical Developments
Classical and Post-Classical Developments
Nicolaus Copernicus proposed the heliocentric model in his seminal work, De revolutionibus orbium coelestium (1543). This model suggested that the Sun, not the Earth, was at the center of the solar system, with planets orbiting it in circular paths.
Galileo Galilei later defended Copernicus’ model with evidence obtained through his telescopic observations, such as the phases of Venus and the moons of Jupiter, which supported the idea of celestial bodies orbiting centers other than Earth.
Johannes Kepler built upon Copernicus’ model by introducing the concept of elliptical orbits in his three laws of planetary motion:
1. Planets move in ellipses with the Sun at one focus.
2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
However, Kepler did not explain why planets followed these laws. It was Isaac Newton who later provided the theoretical foundation with his law of universal gravitation, demonstrating how gravity governs planetary motion.
The Invention of the Telescope and Deep Space Astronomy
The Invention of the Telescope and Deep Space Astronomy
In the 20th century, it was proven that the Milky Way is just one of many galaxies. Edwin Hubble, using the Hooker Telescope, discovered that other galaxies, like the Andromeda Nebula, exist outside the Milky Way, which led to the understanding that the universe is made up of multiple galaxies.
Time and time again, we think we have found what the center of the Universe is, and we are proven wrong. With the ancients it was the Earth, then we thought it was the Sun, and then it was revealed that the Sun revolves around the Milk Way, and alas, we now know, even the Milky Way Galaxy, as mighty as it might be, isn't the center of significance. The Universe has no center, as far we know.
We now arrive at present day, with a lot of answered questions, and the best physicists and mathematicians leading the way in the search for the grand unified theory, the theory to rule all theories.
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