Enjoying EarthSky? Subscribe.

245,565 subscribers and counting ...


Find blue-white Rigel at Orion’s foot

If Rigel were as close as our sun, it would outshine the sun by 40,000 times!

Today in science: John Glenn

On February 20, 1962, John Glenn became the 1st American to orbit Earth and the first American space hero.

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.

Hints of a quiet, stray black hole

Theoretical studies predict 100 million to 1 billion black holes in our Milky Way galaxy. So far, astronomers have found about 60. A serendipitous discovery could lead to finding more.

Why no eclipse every full and new moon?

This year, in 2017, there are 12 full moons and 12 new moons, but only four eclipses – two lunar and two solar.

Why can’t we feel Earth’s spin?

We can’t feel Earth’s rotation or spin because we’re all moving with it, at the same constant speed.

Groundhog Day has roots in astronomy

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

February birthstone is the amethyst

Are you a February baby? Here’s some cool info about your birthstone, the amethyst. Plus pics!

Astronomy statement on US travel ban

The International Astronomical Union issued a statement on Monday in response to the U.S. executive order limiting travel from 7 countries. Read it here.