Infinite Space
THe Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye.
Milky Way
THe Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye.
What is it?The Milky Way is a barred spiral galaxy, about 100,000 light-years across. If you could look down on it from the top, you would see a central bulge surrounded by four large spiral arms that wrap around it. Spiral galaxies make up about two-third of the galaxies in the universe.
The Milky Way does not sit still, but is constantly rotating. As such, the arms are moving through space. The sun and the solar system travel with them. The solar system travels at an average speed of 515,000 miles per hour. Even at this rapid speed, the solar system would take about 230 million years to travel all the way around the Milky Way. More...Tucked inside the very center of the galaxy is a monstrous black hole, billions of times as massive as the sun. This supermassive black hole may have started off smaller, but the ample supply of dust and gas allowed it to gorge itself and grow into a giant. The greedy glutton also consumes whatever stars it can get a grip on.
Not only is the Milky Way spinning, it is also moving through the universe. Despite how empty space might appear in the movies, it is filled with dust and gas — and other galaxies. The massive collections of stars are constantly crashing into one another, and the Milky Way is not immune. |
Facts:The Milky Way contains over 200 billion stars, and enough dust and gas to make billions more.
The solar system lies about 30,000 light-years from the galactic center, and about 20 light-years above the plane of the galaxy. More than half the stars found in the Milky Way are older than the 4.5 billion year old sun. The most common stars in the galaxy are red dwarfs, a cool star about a tenth the mass of the sun. Once thought unsuitable for potential life-bearing planets because such bodies would have to be too close to meet the criteria, red dwarfs are now considered potential suspects. As late as the 1920's, astronomers thought all of the stars in the universe were contained inside of the Milky Way. It wasn't until Edwin Hubble discovered a special star known as a Cepheid variable, which allowed him to precisely measure distances, that astronomers realized that the fuzzy patches once classified as nebula were actually separate galaxies. |