arth and the other planets orbit the Sun and together form our solar system. The Sun is a relativly small star and only one of billions. When you look up into the night sky all the stars you see are located in our galaxy, the Milky Way. It was named this due to its milky appearance. Through a telescope the Milky Way galaxy has been found to be made up of countless individual stars that seem relatively close together. This is because from the vantage point of Earth we are looking at the Milky Way on its edge and can't see where the stars are actually located.
Four hundred billion Stars
Scientists have calculated that are about 400 billion stars in our galaxy and measure 100,000 lightyears from end to end. The Milky Way is part of a galaxy cluster that includes 30 other galaxies, the closest of which is the Andromeda nebula.
The Milky Way is a spiral galaxy with a large concentration of stars in its nucleus. The center (or nucleus) of the Milky Way is thick, like other spiral galaxies, where the spiral arms sprout. Our solar system is located on one of these spiral arms at about 25,000 lightyears from the center. To put this in perspective it is located at about two-thirds of the way from the center to the edge of the galaxy.
The spiral arms of the Milky Way rotate around its center. It takes almost 250 million years for our solar system to make one complete rotation. When we look at the galaxy from the southern hemisphere we see the middle of the Milky Way and when we look from the northern hemisphere we see the edge of the galaxy. We can look toward the center of the galaxy but it is mostly hidden by interstellar dust particles.
There are indications that there is a blackhole in the center of the Milky Way. It is also possible that in the large, seemingly empty space around the galaxy, an enormous quantity of invisible, dark matter could be found.