The firing of a spacecraft thruster, sending a yellow stream of exhaust into space.

Iodine thruster could help clear space junk

A commercial nanosat called SpaceTy Beihangkongshi-1 – launched November 2020 – has successfully used an iodine thruster to change its orbit around Earth. This new thruster might help clear space junk by steering small satellites, at the end of their missions, back into Earth’s atmosphere where they’d burn up.

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!

Freezing fog turns trees white.

The beauty of winter 2021

Enjoy photographs of winter 2021 and all of its beautiful snow and unusual icy shapes!

The sun in 2020

See a whole year of sun images, an image a day for 2020, taken by ESA’s Proba-2 satellite.

Is a solar flare the same thing as a CME?

Solar Cycle 25 is here, and that means – in the years ahead – more solar flares and more coronal mass ejections, or CMEs. People sometimes use the words interchangeably, but they’re not the same thing. Here’s the difference.

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.

220 years ago today: 1st asteroid discovered

Giuseppe Piazzi discovered the asteroid Ceres – now considered a dwarf planet – on January 1, 1801.

Why does the New Year begin on January 1?

Where does the New Year’s Day concept come from?

Kelvin Helmholtz clouds near Sandpoint, Idaho.

Kelvin-Helmholtz clouds look like waves in the sky

Clouds in the sky can mimic cresting ocean waves. These photographic clouds are called Kelvin-Helmholtz clouds, and occasionally also go by the name billow clouds or shear-gravity clouds.

Jupiter and Saturn above bright city lights.

Your photos of 2020’s historic Jupiter-Saturn conjunction

Jupiter and Saturn’s great conjunction – where they appeared exceedingly close on the sky’s dome – was December 21. Thank you to EarthSky community members from around the world who captured photos!