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EarthSky

Somber Betelgeuse in Orion’s shoulder

Betelgeuse’s red color indicates a star well into the autumn of its years. In fact, the star is a magnificently rare red supergiant.

What is radiocarbon dating?

At a very steady rate, unstable carbon-14 gradually decays to carbon-12. The ratio of these carbon isotopes reveals the ages of some of Earth’s oldest inhabitants.

Groundhog Day has roots in astronomy

Groundhog Day is tied to the movement of Earth around the sun. It’s the year’s 1st cross-quarter day.

See it! Super Blue Moon eclipse photos

It was a Blue Moon, a supermoon and a moon in total eclipse. EarthSky community members around the world came through as always with awesome photos.

Identify stars in the Winter Circle

Go outside, and look for the waxing gibbous moon tonight. Then notice the stars nearby. Tonight’s moon is within the Winter Circle stars.

Contemplate the apex of the sun’s way

Our sun moves around the center of the galaxy, toward the star Vega. Astronomers call this motion the apex of the sun’s way. One circuit – about 230 million years – is called a cosmic year.

A winding river of stars called Eridanus

Why search for such a faint constellation? Only because it’s very beautiful. Plus seeing Eridanus can give you a kinship with stargazers from centuries ago.

Look for Cassiopeia and the Big Dipper

Watch the celestial clock and its 2 great big hour hands – Cassiopeia and the Big Dipper – as they swing around the North Star every night!

Ocean plastic killing marine turtles

Hundreds of marine turtles die every year after getting tangled in trash – such as plastic ‘six pack’ holders and discarded fishing gear – in oceans and on beaches.

How to translate UTC to your time

The Earth has 24 time zones. Look here to learn how to translate UTC to your local time zone.