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August 12, 2015

The beautiful constellation Sagittarius nudges low across the southern sky on August nights. Right now, it stands quite low in the south as night falls, and sets in the wee hours of the morning.

Sagittarius represents a centaur — a creature that’s half man, half horse. Modern skywatchers, though, are more likely to see a big teapot formed by eight of the constellation’s brightest stars. The handle is on the left, with the spout on the right.

The teapot is bright enough to see even from most cities, whose skies are polluted by the glow of streetlamps and other light sources. To appreciate the constellation’s true glory, though, you need to get away from those lights. Under a dark sky, you can see the soft glow of the Milky Way, which runs through the lid and spout of the teapot.

That glow represents the combined light of millions of stars in the disk of the Milky Way galaxy. In fact, the center of the Milky Way — the hub of its giant disk — lies just above the spout of the teapot.

The glowing path of the Milky Way is interrupted by some dark patches. These are formed by massive clouds of dust. They block most of the light that comes from the galaxy’s heart, so that part of the Milky Way isn’t visible to the eye. Instead, you need telescopes that are sensitive to the infrared, radio, and other wavelengths to penetrate the dust and see the goings-on in the galaxy’s busy hub.

We’ll take you inside that hub tomorrow.


Script by Damond Benningfield, Copyright 2015

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