In something I’m considering making a tradition here at BA Central, here is your Monday morning jaw-dropping spiral galaxy: NGC 634 as seen by Hubble:
[Click to galactinate.]
Isn’t that something? This galaxy is a gorgeous nearly edge-on spiral, about 120,000 light years across or so — slightly bigger than the Milky Way — and 220 million light years away. The press release (at the link above) for this spiral talks about a supernova that blew up in this galaxy back in 2008, and I was going to write about that, but then something else tickled my brain.
Look at the picture. The disk of the galaxy, like in most spirals, is ribboned with dark dust lanes, huge clouds of complex organic molecules expelled by stars being born and stars dying. It’s pretty common to see them, but what struck me is the asymmetry of the lanes: they are darker on the bottom than at the top. The overwhelming impression is that we’re looking down on the spiral, so the dust lanes are more obvious on the near side than the far side.
This cannot be a physical effect of having dust only on one side of the galaxy. If it were, then random chance would make it pretty unlikely to have it on the side tipped toward us. Plus, I realized that I’ve seen this before! Read More