Question

How many suns can fit in our galaxy?

Answer 1

Hint: Many solar systems together make up a galaxy. The Milky Way is the galaxy in which Earth’s solar system exists. It is estimated that one edge of the Milky Way is several light years away from us and it is known that billions of stars exist in our galaxy.

Complete step-by-step solution:
Our galaxy is known as the Milky Way. This means that the whole solar system lies inside the Milky Way. As the Milky Way galaxy stretches out far beyond,. The edge of the galaxy is about 950,000 light years away.

Sun is a star. A star is a big ball of gases which gives out its own energy. The sun is an average sized star but there are many types of stars depending on the size. We can only see stars as a speck of light in the dark because they are several light years away from us. In our Milky Way galaxy alone, there are estimated 100-400 billion stars.

We know that,
$1light\,year=9.46\times {{10}^{15}}m$

Therefore,
$950,000\,light\,years=950,000\times 9.46\times {{10}^{15}}=8.9\times {{10}^{21}}m$
The surface area of the sun is $6.09\times {{10}^{18}}{{m}^{2}}$

Therefore, the number of sun sized stars that can fit in one edge of the galaxy is-
$\dfrac{8.9\times {{10}^{21}}}{6.09\times {{10}^{18}}{{m}^{2}}}=1.46\times {{10}^{3}}$

Therefore, $1.46\times {{10}^{3}}$ stars can be fitted in one edge of the galaxy, so at each edge $1.46\times {{10}^{3}}$ stars can be fitted which means that millions of stars can exist in the Milky Way alone.

Note:
There are many other galaxies beyond The Milky Way. A collection of galaxies is known as the universe while a collection of solar systems is called a galaxy. Light years is an astronomical unit of distance which is used for large distance, it is the distance travelled by the light in one year.