Because they can see them.
galaxies
The universe.
Smaller galaxies do. Larger galaxies contain billions or even trillions of stars.
Stars and Galaxies are related because a galaxy is a system of billions of stars, gases, and dust.
Like our galaxy contains billions of stars, the universe contains billions of galaxies.
Yes and no, as there are a huge amount of starts. Only a few thousand stars can be seen by the naked eye. You can count those. Every star you see is in our galaxy and there are many more stars in our galaxy that you cannot, about 100 billion. Then there are billions of other galaxies. So we can estimate the amount of stars in the universe, but not count all of them.
A galaxy contains billions of stars. A universe contains billions of galaxies.
Billions of stars make up galaxies. Galaxies are vast systems of stars, planets, gas, and dust that are held together by gravity. Our Milky Way galaxy, for example, consists of billions of stars including our Sun.
Galaxies
a galaxy is billions of stars
Galaxies.
Galaxies.