StarDate on Claycord – July 22, 2013

July 22, 2013 · 1 comment

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1 J. July 22, 2013 at 7:16 PM

Sagittarius
StarDate: July 22, 2013

A celestial teapot rolls across the southern sky on summer nights, venting “steam” that appears to rise high across the sky.

In mythology, Sagittarius represents a centaur — a creature that’s half man and half horse — holding a bow and arrow. But modern eyes are more likely to see a teapot, which is formed by a grouping of eight moderately bright stars. The handle is on the left, with the spout on the right.

The “steam” that rises from the spout is the subtle glow of the Milky Way — the band that outlines the disk of our home galaxy. And the galaxy’s heart is right above the spout.

Unfortunately, the heart is hidden behind clouds of interstellar dust, so it’s not visible to the human eye. In fact, it’s hard to see much detail at visible wavelengths even with big telescopes. So astronomers must look at wavelengths of light that penetrate the dust, such as infrared and radio waves.

The combination of wavelengths reveals that the galactic center is teeming with stars and giant clouds of gas. A black hole that’s about four million times as massive as the Sun sits in the middle of this busy scene, surrounded by several star clusters. We’ll have more about the galactic center tomorrow.

In the meantime, look for Sagittarius low in the south-southeast as darkness falls, to the right of the Moon. The Milky Way is tough to make out through the moonlight, but the Moon will rise later each night, providing darker skies for viewing our galactic home.

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