Monday, March 23, 2009

Galaxies - Near, Far, and Really Far

Click on the images for larger views
All of the pictures you see here were taken with the same lens, my Canon 300mm f/4 telephoto lens. They are all galaxies of various types and sizes. They also vary in incredible distances from us. The image above is the great Andromeda Galaxy (M31), our nearby twin sister. She is our nearest large neighbor, right next door to our own Milky Way galaxy. Someone (or Thing) is standing on one of M31's planets, looking at our galaxy right now and seeing a similar looking spiral of stars, dust and gas. M31 is quite a distance from us (2.5 million light years away), but it is so big, we can see it without optical aide as a fuzzy star in the constellation Andromeda. To see it, however, you need to be away from the light pollution of our cities and is best seen in our Fall and Winter sky. There are two companion galaxies rotating around M31, one fairly obvious on this side and one much smaller directly on the other side. Astronomers have studied it's motion, and it is on a collision course with the Milky Way. To see what this event will look like, see the image of the next galaxy below.
This the Whirlpool Galaxy, M51 and it's companion NGC5195. Click on the image to get a closer look and notice the the odd shape of the smaller galaxy. NGC5195 has collided with M51. What you are seeing it the stars of the galaxy pushed out and distorted like a water sprinkler. During the collision, the stars in the galaxies usually do not collide. This is because of the great distances between the stars, but gravitational attraction from the passing stars, dust, gas and dark matter, tugs and distorts the galaxies into new shapes. This image was taken with the same lens, but M51 is a smaller image because it is almost ten times further away (23 million light years). Lots of galaxies, even further away are picked up with the one hour exposure. The galaxy numbers you see are from various catalogs. If you know where to look and are away from the city lights, you can see it with a pair of binoculars, looking like a fuzzy star. It sits near the last star of the Big Dipper's handle like in the chart below.

Now we make a big jump. With the same lens (and same field of view), we are looking at galaxies that are about 60 million light years away, 24 times further away than the Andromeda Galaxy. These is a cluster of galaxies, known as the Virgo Cluster (most of them are in the constellation Virgo, now in the Springtime sky). We see quite a few galaxies in this image, but it is only a small part of the close to 2000 galaxies. This cluster is also part of an even larger Supercluster, of which our Milky Way, M31 and a few other galaxies (the Local Group) also belong to. Notice that a few of these galaxies look as big as M51, but this only shows you how huge these galaxies really are to take up the sames view and yet be almost 3 times further away than M51. I labeled the galaxies in the image below using star charting software.
It always amazes me how large the sky is above us. It is very hard to comprehend these great distances. It also amazes me that 99% of the people on the Earth never look up at the night sky.

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