Astronomy 1
Siužetinės Linijos Tekstas
- 14 billion years ago, the universe was empty. Then the Big Bang occurred. The Big Bang was the event that caused the universe to expand to where it is today
- The Big Bang theory states that the universe we saw today was only a few millimeters across before expanding into the current-day universe that we live in
- At first, the universe had no real shape. The first force to emerge after the Big Bang was gravity. For our universe to form. the gravity was just right. More gravity would lead to black holes and too little gravity would lead to everything flying apart.
- After the force of gravity kicked in, the universe started expanding faster than light: from the size of an atom to the size of a baseball within seconds. A new unit of time was needed to keep track of this speed: planck time.
- Planck time is so small that one second is equal to "1 billion billion billion billion billion" planck times. In under a second, the universe went from the size of our hand to larger than our solar system
- Another unit of time is an astronomical unit, a unit of measurement equal to 149.6 million kilometers
- The universe was not just empty matter, it was full of objects like planets, moons, nebulas, and exoplanets. A planet is a body that orbits a star and is large enough to become round due to its own gravity.A moon is a body that orbits another massive body (such as a planet)A nebula is an immense cloud of gas and dust in space, where stars are born.An exoplanet is a smaller planet that is outside the Solar System.
- A light year is a unit of astronomical distance that shows how far light travels. For example, if something is one light year away and we look at it through a telescope, we are actually looking at that object 1 year ago, essentially "traveling through time:
- All of these objects orbit around a star, a luminous globe of gas which produces heat and light.All of these objects come together to make a galaxy, which is a group of stars, gas, and related matter held together by gravity. We live in the Milky Way Galaxy, which spans nearly 100 light years.
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