The image shows a tiny region of the sky in the constellation Hercules. The width of the object is approximately 1/40th the diameter of the full moon in the sky, which is just barely too small for the eye to discern. The object is also too faint to see without a telescope.
The odd-looking structure appears to be two spiral galaxies in the process of colliding: the blueish curve is a galaxy that has been gravitationally stretched into an enormous stream of stars and gas by the reddish galaxy, which is itself being gravitationally pulled apart. All of this action is taking place approximately 365 million light-years away. The process of galaxy collisions takes hundreds of millions of years to unfold, so what we’re seeing is a snapshot of the process — if we could look at it again in another thousand years it would look much the same. The end product of such collisions is believed to be a single elliptical galaxy.
The website showing this enigmatic image is the Sloan Digital Sky Survey Navigate Tool. The SDSS has mapped over a quarter of the sky, and provides all kinds of data (for free!) for over a million objects (mostly galaxies and quasars). It’s so useful that I based most of my doctoral research on quasar spectroscopy from the SDSS.
You can use the Navigate Tool to have some fun. Below is a list of celestial coordinates for different types of objects. You can use the tool to zoom in and out, pan around the sky, and even print out pretty pictures. Just copy and paste the the RA and Dec for each object into the appropriate boxes on the Navigate Tool and away you go. (RA and Dec stand for “Right Ascension” and “Declination” which are really just longitude and latitude for the sky.)
NGC 4565 (the Needle Galaxy)
RA: 12:36:18, Dec: +25:59:00
M13 (the Hercules Globular Cluster)
RA: 16:41:41, Dec: +36:27:37
NGC 5194 (the Whirlpool Galaxy)
RA: 13:29:54, Dec: +47:12:00
IC 5146 (the Cocoon Nebula)
RA: 21:53:28.7, Dec: +47:16:01
NGC 2632 (the Beehive Cluster)
RA: 8:40:06, Dec: +19:59:00
NGC 3034 (the Cigar Galaxy)
RA: 9:55:48, Dec: +69:41:00
NGC 4406 (heart of the Virgo Cluster of galaxies)
RA: 12:26:12, Dec: +12:57:00
Stephan’s Quintet
RA: 22:35:57.5, Dec: +33:57:36
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