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Sunflower Galaxy

March 31, 2011

If you're an astronomer who studies faint, wispy objects like spiral galaxies, then this is your time to shine. The Moon will be new in a few days, so it doesn't fill the sky with its glow. With the pesky moonlight out of the way, those faint galaxies shine at their best.

One example is M63, a spiral galaxy in the constellation Canes Venatici. It's in the eastern sky in early evening, and soars high overhead later on. It's also known as the Sunflower Galaxy for its beautiful shape and color. It's bright, so it's visible through just about any telescope. But seeing any detail in its structure is enhanced by the moonless night.

In many ways, M63 resembles our own galaxy, the Milky Way. It's about the same size and mass, and it appears to have a central black hole that's about twice the size of the one at the heart of the Milky Way.

Also like the Milky Way, the outer edge of the galaxy's disk is bent, and probably for the same reason: the gravitational pull of companion galaxies. In the case of M63, the companions appear to pull out long, faint streamers of stars that show up in long-exposure images.

And there's one more similarity: Both galaxies are surrounded by haloes of dark matter. It far outweighs the bright matter, so it exerts a strong pull on the galaxy's stars and gas clouds. But the dark matter produces no energy of its own, so there's no way to see it -- no matter how dark the skies are.


Script by Damond Benningfield, Copyright 2011


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