The words " solar system" refer to the Sun and all of the objects that travel around it. These objects include planets, natural satellites such as the Moon, the asteroid belt, comets, and meteoroids. Our solar system has an elliptical shape and is part of a galaxy known as the Milky Way. The Sun is the center of the solar system. It contains 99.8% of all of the mass in our solar system. Consequently, it exerts a tremendous gravitational pull on planets, satellites, asteroids, comets, and meteoroids. Astronomers believe the solar system formed 4.5 billion years ago. However, they differ in their beliefs about how the system formed. Some believe the whole solar system formed from a single flat cloud of gas, while others believe it formed when a huge object passed near the Sun, pulling a stream of gas off of the Sun. Astronomers theorize the planets then formed from this gas stream.
A galaxy is, by definition, any large collection of stars that can be recognized as a distinct physical entity. In terms of the number of stars, a small 'dwarf irregular' galaxy like the Small Magellanic Cloud, has about one billion stars in it, but there are even smaller systems that are recognized as galaxies such as the Leo I and II dwarf galaxies with about 1 million stars in them, and the Draco System with a few hundred thousand stars in it. The largest star cluster, a globular cluster called Messier 15 has about 6 million stars, so we see that for small galaxies, there is a blurring together of what we mean by a galaxy and a large star cluster. In addition to their mass and numbers of stars, a galaxy is a collection of stars and gas which move through the universe independently of the Milky Way. Globular clusters are roundish swarms of stars that orbit the Milky Way, while the Leo and Draco Systems seem to be independent collections of stars.
Many galaxies also continue to form new generations of stars. The Milky Way, and all spiral shaped galaxies like it, produce new stars at a rate of one or two stars per year. These stars are formed in the vast interstellar clouds that account for about 1 to 10 percent of the mass of these galaxies. Globular star clusters, on the other hand, are not currently forming stars because this activity happened billions of years ago and then stopped once all of the gas and dust clouds were used up.
Overall solar systems are a part of a galaxy which makes galaxies much larger than a solar system.
Subscribe to:
Post Comments (Atom)
6 comments:
You did a good job in explaining the differences betweeen solar systems and galaxies. Naming a few solar systems would have been nice, like you did for the galaxies.
Nick,
I liked the examples of all of the different types of galaxies. It really helps spell out all of the differences in them. You were a little lacking in describing solar systems. But you covered all of the basics. I really liked the interesting fact that galaxies create stars. I never knew that!!! It's true what they say, you learn a new thing every day.
Billy
Nice Job Nick..I really liked the info about the stars forming at the end of your blog. Great job
Keri
Good Job! you have some very good points about galaxies and solar systems. i agree with what you said about galaxies. there is so many things in our universe that we will never be able to see or experience or touch. its scary to think that we're not the only ones our there!!!
Nick,
I really liked the facts you put in your first paragraph!! Nice info on the galaxies!! Great Job.
Rachel
The sheer majesty of your blogerness is utterly breathtaking. You are the apple of my eye.
Well done
-Dustin
Post a Comment