A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
The Milky Way Galaxy
Our Sun is just one star in the Milky Way galaxy located in a spiral arm about two-thirds of the way from the galaxy center.
Our Milky Way Galaxy is A Spiral Galaxy
When you look up at stars in the night sky, you’re seeing other stars in the Milky Way. If it’s really dark, far away from lights from cities and houses, you can even see the dusty spiral arm bands of the Milky Way stretch across the sky.
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How many stars are there in the Milky Way Galaxy?
Astronomers estimate there are about 100 thousand million stars in the Milky Way alone!!
- Outside of our own Milky Way Galaxy, there are millions upon millions of other galaxies too!
How Long would it take to count to a billion?
What's the highest anyone has ever counted?
What is at the center of our Galaxy?The very center of the Milky Way is known as the Galactic Center. It has a unique collection of very interesting objects that have intrigued astronomers for decades including a supermassive black hole.
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What is a Black Hole?
The most massive stars - those that have more than 10 times the mass of the Sun may become black holes when they die. A black hole is an object with gravity so strong that nothing, not even light, can escape. After a very massive star dies in a supernova explosion, more than five times the mass of the Sun may be left. The gravity of this mass is so strong that the gas is pulled inward, packing the gas into a smaller and smaller space. The stars gas becomes squeezed so hard that the star converts into a black hole and its intense gravity will not allow even light to escape.
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Topic Tips
- Our Sun is just one star in the Milky Way galaxy located in a spiral arm about two-thirds of the way from the galaxy center.