Sunday, December 14, 2008

Sagittarius: Messier than Most

Putting together these almost-monthly astrology reports (I missed a few, but no one of those zodiac signs clamored for a report, unlike Gemini) has taught me a lot about the science of astronomy. Relatively speaking. I started out knowing pretty much nothing, so it doesn't take much to add up to "a lot." By comparison, I've learned only a smidge about astrology.

These images, left, are icons of Messier objects; that is, the 110 nebulae, star clusters, galaxies--objects known as "deep sky objects"--which French astronomer Charles Messier cataloged in the 18th century.
From the SEDS Messier Database.

It's so cool to me how science and stories bump along together, sometimes happily, sometimes not. (Oh, that's my Pisces speaking: I love things that move in opposite directions but are tied together with a ribbon.) And I never get over how gorgeous the Universe looks from here.

Lucky Sagittarius!
Not only do astrologers says the sign is ruled by benevolent Jupiter, but astronomers say its constellation contains the high number of 15 Messier objects in "its rich milky way starfields" (as All the Sky puts it)-- because the dense center of our galaxy lies in its field. They include star-forming nebulae, a "breathtaking" star cloud, star clusters, an asterism...and two minor galaxies!
The Sagittarius Dwarf Elliptical Galaxy (Sag DEG) orbits the Milky Way and is its second-closest neighboring galaxy.

provided this image, right, of M54 [Messier 54] and notes "in 1994, the exciting discovery was made that M54 was probably not a member of our Milky Way at all, but of a newly discovered dwarf galaxy [Sag DEG]!"

Now don't go confusing Sag DEG with the other minor galaxy, Sag DIG, the Sagittarius Dwarf Irregular Galaxy.
DEG is only about 60,000 light-years from Earth.
DIG is 4.2 million light-years away.

P.S. Happy birthday, Matt!

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