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The secrets of noctilucent clouds

Noctilucent cloud season has returned to Earth’s high latitudes. These "night-shining" clouds are beautiful ... photos here.

Happy World Oceans Day 2021

World Oceans Day has been celebrated every year on June 8 since 1992. It's a day to raise awareness about how we're connected to the oceans - no matter where we live on Earth - and what we can do to protect ocean habitats.

What makes a halo around the sun or moon?

A large ring or circle of light around the sun or moon is called a 22-degree halo by scientists.

What are the 2021 hurricane names?

The World Meteorological Organization chooses hurricane names several years in advance. Find hurricane names for 2021 here.

See it! May 26, 2021, lunar eclipse photos

Enjoy a few photos of the May 21, 2021 lunar eclipse from EarthSky friends around the world. Thanks so much to all who shared your photos with us!

Clouds that look like waves in the sky

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

Why not an eclipse at every full and new moon?

If the moon orbited Earth on the same plane that Earth circles the sun, then we'd have a total lunar eclipse at each full moon, and a total solar eclipse at each new moon. But that doesn't happen because the lunar orbit is inclined to Earth's orbit by about 5 degrees.

Listen: Have aliens already visited us?

A podcast featuring Harvard theoretical physicist Avi Loeb, on the subject of whether 'Oumuamua - the strange object that swept through our solar system in 2017 - is an artifact of an alien intelligence.

Dates and times of moon phases in 2021

Find out when the next new moon, 1st quarter moon, full moon or last quarter moon will occur in 2021.

Photos of the supermoon, April 2021

The first of 2 spring supermoons in 2021 took place on April 26 or 27 (depending on your location on Earth). We received many wonderful submissions from you, our readers. Here's a gallery of some favorites. Thanks to all who submitted!