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Saturday, November 28, 2015

Earthsky Tonight, January 20, 2010: Achernar, the end of the River

Courtesy of EarthSky
A Clear Voice for Science

Evening winter sky from the southern United States
Eridanus as seen from the southern United States

Today’s chart is almost just like the January 16 chart. But today we’ve changed our observing location. Normally, our charts are set for the geographical center of the continental U.S. – say, somewhere in Kansas. Today’s chart is set to the extreme southern U.S.

It’s as if we’re gazing at stars from the southernmost part of the country . . . maybe along the Texas/Mexico border, or from the Florida Keys. From most of the U.S., the bottom part of constellation Eridanus the River disappears below the southern horizon. It’s only if you’re in the extreme southern U.S., or farther south on Earth’s globe, that you can see the famous star that marks the End of the River.

The star marking the End of the River star is very bright. But, bright or not, you’ll never see it anywhere but right next to the southern horizon if you’re observing from the U.S. And you won’t see it at all from the northern states. That’s because this star is located very far to the south on the celestial sphere, the imaginary dome of stars surrounding Earth.

This star makes only a tiny arc above the southern horizon from the southern U.S., so you have to be looking at just the right time to see it — for example, at nightfall and early evening tonight. The star’s name is Achernar. If you see it, you’ll never forget it!

Achernar’s rising and setting time in your sky

Written by Deborah Byrd

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