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Editors of EarthSky

Star aligns with planetary nebula to create diamond ring

It looks like the diamond ring effect seen during total solar eclipses. It's really a distant, dying star and its shell of gas, with another star in front of it.

Astronomers make most precise measurement yet of expanding universe

A new analysis says that 10.8 billion years ago, the universe was expanding by one percent every 44 million years.

Ride along with a rocket to space

What a ride! Cameras mounted on the upper stage of a Soyuz rocket on April 3, 2014 looked earthward during a satellite launch.

Biggest galaxy cluster bigger than thought

El Gordo - the largest galaxy cluster in the universe - is about 3 million billion times more massive than our sun, roughly 43 percent more massive than earlier estimates.

Computer maps 21 distinct emotional expressions

... even seemingly contradictory ones, like "happily disgusted."

Hidden ocean discovered on Saturn’s moon Enceladus

A large ocean under Enceladus' icy surface supplies the water that's been seen spraying out of the "tiger stripes" on its surface, suggests new research.

Mercury has a long history of exploding volcanoes

Throughout extended periods of its history, the surface of planet Mercury crackled with volcanic explosions, a new analysis suggests.

Why do zebras have stripes? To keep bugs off, says study

Researchers say they've solved the riddle of why zebras have stripes: The stripes act like insect repellant, keeping away blood-sucking flies, say researchers.

New image: Two contrasting galaxies

A new image shows two galaxies, close to each other in space, but with very different histories - small spiral NGC 1317 and the large battle-scarred NGC 1316.

Mars opposition happens this month: It’s really easy to see

Earth and Mars are converging for a beautiful close encounter in April, an event astronomers call "the opposition of Mars."