Introduction
If you look up at the sky at night, you can often see a band of stars that stretches across the sky like a river of milk. By viewing closely through a pair of binoculars, you will see that it is actually a dense collection of stars. This is the milky way, and what you are seeing is our own galaxy from the inside. Our sun is one of over 200 billion stars that make up our milky way.
The local group
Our galaxy may seem to be immense and of vast importance, but even the Milky way is not isolated in space.It is one of approximately 30 galaxies that make up the Local Group, an enormous collection of galaxies that stretches over millions of light years. Most of the galaxies in the local group are clustered around the strong gravitational pulls of the milky way and the similar Andromeda Galaxy. However, just as galaxies group together to form clusters, clusters are attracted to each other to form superclusters! These are immense clouds of galaxies that can stretch for hundreds of millions of light years.
The Milky Way
Known as the milky way, our galaxy contains over 200 billion stars. It looks like a giant spiral from above but if it was viewed from the side it would appear as a flat band of stars. This is because although the milky way is 100,000 light years long, it is only 2000 light years thick. Our solar system lies halfway along one of the spiral arms. Scientists believe that in the centre of milky way there is an enormous black hole with a mass greater than 2.5 million suns. It is not active at the moment, but it may come back to life again.
Galactic partners
Orbiting our galaxy, just as the Earth orbits the sun, are two enormous satellite galaxies called Magellanic Clouds. The large and the small Magellanic clouds consists of thousands of stars and orbit the milky way every 1.5 billion years. The large Magellanic cloud is made from the same mix of gas and stars as the milky way, but it is less than one twentieth as large and too small to grow spiral arms. It lies 160,000 light years away. The small Magellanic cloud is 190,000 light years away and is slowly pulled apart by the gravity of the milky way.
Some important facts
1) The milky way Spins more slowly in its densely packed centre and its spiral arms than it does in its outer regions. Its average speed is around 230km per second.
2) The centre of the milky way is marked by a tiny radio source called Sagittarius A*. This is emitted by the gas around a black hole.
3) The milky way can be seen most clearly in both hemispheres between june and september. It appears as a band because the galaxy is flat, and we are viewing it from inside.
4) Our solar system lies halfway along the Orion arm of the milky way. The sun takes 220 million years to orbit the centre of galaxy.
Facts and Figures
Diameter : 100,000 light years
Depth : 2,000 light yeras
Mass : 1,000 million million solar masses
Time taken to rotate : 220 million years
If you look up at the sky at night, you can often see a band of stars that stretches across the sky like a river of milk. By viewing closely through a pair of binoculars, you will see that it is actually a dense collection of stars. This is the milky way, and what you are seeing is our own galaxy from the inside. Our sun is one of over 200 billion stars that make up our milky way.
The local group
Our galaxy may seem to be immense and of vast importance, but even the Milky way is not isolated in space.It is one of approximately 30 galaxies that make up the Local Group, an enormous collection of galaxies that stretches over millions of light years. Most of the galaxies in the local group are clustered around the strong gravitational pulls of the milky way and the similar Andromeda Galaxy. However, just as galaxies group together to form clusters, clusters are attracted to each other to form superclusters! These are immense clouds of galaxies that can stretch for hundreds of millions of light years.
The Milky Way
Known as the milky way, our galaxy contains over 200 billion stars. It looks like a giant spiral from above but if it was viewed from the side it would appear as a flat band of stars. This is because although the milky way is 100,000 light years long, it is only 2000 light years thick. Our solar system lies halfway along one of the spiral arms. Scientists believe that in the centre of milky way there is an enormous black hole with a mass greater than 2.5 million suns. It is not active at the moment, but it may come back to life again.
Galactic partners
Orbiting our galaxy, just as the Earth orbits the sun, are two enormous satellite galaxies called Magellanic Clouds. The large and the small Magellanic clouds consists of thousands of stars and orbit the milky way every 1.5 billion years. The large Magellanic cloud is made from the same mix of gas and stars as the milky way, but it is less than one twentieth as large and too small to grow spiral arms. It lies 160,000 light years away. The small Magellanic cloud is 190,000 light years away and is slowly pulled apart by the gravity of the milky way.
Some important facts
1) The milky way Spins more slowly in its densely packed centre and its spiral arms than it does in its outer regions. Its average speed is around 230km per second.
2) The centre of the milky way is marked by a tiny radio source called Sagittarius A*. This is emitted by the gas around a black hole.
3) The milky way can be seen most clearly in both hemispheres between june and september. It appears as a band because the galaxy is flat, and we are viewing it from inside.
4) Our solar system lies halfway along the Orion arm of the milky way. The sun takes 220 million years to orbit the centre of galaxy.
Facts and Figures
Diameter : 100,000 light years
Depth : 2,000 light yeras
Mass : 1,000 million million solar masses
Time taken to rotate : 220 million years
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