Why are these sand dunes on Mars striped? No one is sure. The featured image shows striped dunes in Kunowsky Crater on Mars, photographed recently with the Mars Reconnaissance Orbiter’s […]

What is the Small Magellanic Cloud? It has turned out to be a galaxy. People who have wondered about this little fuzzy patch in the southern sky included Portuguese navigator […]

What causes sprite lightning? Mysterious bursts of light in the sky that momentarily resemble gigantic jellyfish have been recorded for over 30 years, but apart from a general association with […]

All of the other aurora watchers had gone home. By 3:30 am in Iceland, on a quiet September night, much of that night’s auroras had died down. Suddenly, unexpectedly, a […]

In the mid 19th century, one of the first photographic technologies used to record the lunar surface was the wet-plate collodion process, notably employed by British astronomer Warren De la […]

The South Celestial Pole is easy to spot in star trail images of the southern sky. The extension of Earth’s axis of rotation to the south, it’s at the center […]

Familiar stars of a northern winter’s night shine in this night skyview, taken near Zhangye, Gansu, China and the border with Inner Mongolia. During the early hours of December 17 […]

Yes, but have you seen a movie of Jupiter and Saturn’s Great Conjunction? The featured time-lapse video was composed from a series of images taken from Thailand and shows the […]

What does the Earth look like during a total solar eclipse? It appears dark in the region where people see the eclipse, because that’s where the shadow of the Moon […]

From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a […]