What is Astronomy?
Astronomy is a natural science that examines celestial objects and events (from the Ancient Greek "o" (astronoma), "science that investigates the rules of the stars"). In order to describe their creation and evolution, it makes use of mathematics, physics, and chemistry. Planets, moons, stars, nebulae, galaxies, and comets are among the interesting celestial bodies. Supernova explosions, gamma ray bursts, quasar, blazar, pulsar, and cosmic microwave background radiation are examples of relevant phenomena. Astronomy is the study of everything that comes from outside the atmosphere of the Earth. Astronomical cosmology is the study of the cosmos as a whole.
That’s pretty much how the universe began. Because it got so big and led to such great things, some people call it the "Big Bang." But maybe a better name would be the "Everywhere Stretch." What do you think? The big bang is actually how astronomers explain the way the universe began. It is the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now—and it is still stretching!
In 1927, an astronomer named Georges Lemaître had a big idea. He said that a very long time ago, the universe started as just a single point. He said the universe stretched and expanded to get as big as it is now, and that it could keep on stretching. The universe is a very big place, and it’s been around for a very long time. Thinking about how it all started is hard to imagine. Just two years later, an astronomer named Edwin Hubble noticed that other galaxies were moving away from us. And that’s not all. The farthest galaxies were moving faster than the ones close to us. This meant that the universe was still expanding, just like Lemaître thought. If things were moving apart, it meant that long ago, everything had been close together. Everything we can see in our universe today—stars, planets, comets, asteroids—they weren't there at the beginning. Where did they come from?When the universe began, it was just hot, tiny particles mixed with light and energy. It was nothing like what we see now. As everything expanded and took up more space, it cooled down.
In 1927, an astronomer named Georges Lemaître had a big idea. He said that a very long time ago, the universe started as just a single point. He said the universe stretched and expanded to get as big as it is now, and that it could keep on stretching. The universe is a very big place, and it’s been around for a very long time. Thinking about how it all started is hard to imagine. Just two years later, an astronomer named Edwin Hubble noticed that other galaxies were moving away from us. And that’s not all. The farthest galaxies were moving faster than the ones close to us. This meant that the universe was still expanding, just like Lemaître thought. If things were moving apart, it meant that long ago, everything had been close together. Everything we can see in our universe today—stars, planets, comets, asteroids—they weren't there at the beginning. Where did they come from?When the universe began, it was just hot, tiny particles mixed with light and energy. It was nothing like what we see now. As everything expanded and took up more space, it cooled down.
The tiny particles grouped together. They formed atoms. Then those atoms grouped together. Over lots of time, atoms came together to form stars and galaxies.
The first stars created bigger atoms and groups of atoms. That led to more stars being born. At the same time, galaxies were crashing and grouping together. As new stars were being born and dying, then things like asteroids, comets, planets, and black holes formed!How long did all of this take? Well, we now know that the universe is 13,800,000,000 years old—that’s 13.8 billion. That is a very long time.
Picture of Big Bang happening 13.8 billion years ago
Black Hole-The mystery
Don't be misled by the term; a black hole is anything but void. Instead, there is a lot of stuff crammed into a little space; imagine a star 10 times as big as the Sun being crammed into a sphere the size of New York City. As a result, there is a gravitational force that is so powerful that even light cannot escape. These bizarre objects, which are often regarded as the most interesting things in space, have just been given a fresh perspective by NASA instrumentation.Black holes are invisible to telescopes that look for light, x-rays, or other types of electromagnetic radiation. But by seeing how they affect neighboring matter, we may deduce the existence of black holes and study them. A black hole will accrete matter, or pull it inward, if it passes through a cloud of interstellar matter, for instance. A normal star may experience a similar behavior as it approaches a black hole. In this situation, when the star is being drawn toward the black hole, it may rip apart. The heated and accelerated attracting matter radiates x-rays into space as it accelerates and warms up. Recent findings provide some enticing evidence that black holes have a significant impact on the local communities.
References:
1. https://science.nasa.gov/astrophysics/focus-areas/what-powered-the-big-bang
2. https://science.nasa.gov/astrophysics/focus-areas/black-holes
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