Wednesday, January 16, 2013

Stoking the imagination

Now is a good time to go looking for the constellation Fornax, the Furnace, especially if you are as far south as I am, here on the Tropic of Cancer.

Except there's not much to go looking for. Two or three stars of the 4th or 5th magnitude, which means you won't see anything at all unless you have a clear, dark night, just a bare bend in the river Eridanus, which itself is nothing much to look at. When we peer into Fornax, we are looking down out of the pancake-shaped Milky Way Galaxy, away from the most exciting star-rich parts of the sky for visual observers.

But if you have a telescope and you are interested in the universe beyond the Milky Way, then Fornax is a good place to stalk, because there won't be much local stuff in the way. The Hubble Space Telescope turned its big eye to Fornax to make the Hubble Ultra Deep Field image. The most distant object ever seen in the universe is in Fornax (and in the Hubble UDF).

The cluster of galaxies in the above image is in Fornax, one of the closest clusters to our own, only about 40 million light-years away (click to enlarge). Every blurry object in the photo is a galaxy, including the lovely barred spiral in the lower left-hand corner, every galaxy with tens of billions of stars, every star (well, we don't know this for sure) with planets.

And what about the thousands of sharp little dots in the image? Those are stars in our own galaxy, between us and the flat edge of the pancake. The 100,000-light-year-wide Milky Way Galaxy is about 2000 light-years thick where we are, and we are more or less in the middle, so between us and the edge there's a sprinkling (sprinkling!) of neighbors. And then –- empty (?) space.

. If the Milky Way were a frisbee, the Fornax cluster of galaxies would be other frisbees and tennis balls and softballs at the other end of a football field.

So, anyway, I look into the dark furnace and know that its actually alight with galaxies and stars, and I think of Thoreau, who thought it would be well if poets and saints did not spend so much time under roofs.