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Milky way
Spiral galaxies
Elliptical galaxies
Irregular galaxies
Quasars
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It might feel as if it would be pretty simple to find out things about our own galaxy since it's so close to us, but instead the closeness makes it difficult for us to study it. Thanks to better astronomical instruments we have managed to find out a lot about the Milky way during the last century.

Milky way

The earth and our Sun formed some five billion years ago, and since than we have circled the center of the Milky way about 20 times. We are quite far away from the center of the galaxy which makes it very difficult for us to find out what is hiding there; it might be a black hole

From observations astronomers now think of the galaxy as a thin, circular disk with much gas and dust. The young stars, like the Sun, can be found in one of the four main spiral arms. By analysing astronomical data astronomers have found that the Sun is moving in the direction of the constellation Cygnus with a speed of 220 km/s (140 miles/s) and it takes the sun about 240 million years to complete a close orbit. The solar system is located towards the edge of our galaxy, at about 26,000 light-years from the centre.

The centre of the galaxy lies in the direction of the constellation Sagittarius. The nucleus of the Galaxy contains a compact radio source and hot, ionized gas.

It is believed that the Milky way once was a spherical galaxy, but later the gas collapsed into a disk-shaped distribution as we see it now. Stars are still forming, mostly in the spiral arms, from the gas and dust that remain in the disk.


26th July 2000
Sarah Amandusson
www_astro@mssl.ucl.ac.uk