Plutos Sputnik Planum
22.11.2016

Is there an ocean below Sputnik Planum on Pluto? The unusually smooth 1000-km wide golden expanse, visible in the featured image from New Horizons, appears segmented into convection cells. But how was this region created?

Perseid Meteors over Turkey
1.08.2017

The Perseid Meteor Shower, usually the best meteor shower of the year, will peak late next week. A person watching a clear sky from a dark location might see a bright meteor every minute.

An Iridescent Cloud Over France
13.04.2004

Why would a cloud appear to be different colors? A relatively rare phenomenon known as iridescent clouds can show unusual colors vividly or a whole spectrum of colors simultaneously. These clouds are formed of small water droplets of nearly uniform size.

Spiral Galaxies in Collision
21.11.2004

Billions of years from now, only one of these two galaxies will remain. Until then, spiral galaxies NGC 2207 and IC 2163 will slowly pull each other apart, creating tides of matter, sheets of shocked gas, lanes of dark dust, bursts of star formation, and streams of cast-away stars.

Retrograde Mars
11.05.2008

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

Saturns Moons Dione and Titan from Cassini
20.04.2010

What would it be like to see a sky with many moons? Such is the sky above Saturn. When appearing close to each other, moons will show a similar phase. A view with...

Space Shuttle Rising
25.05.2011

What's that rising from the clouds? The space shuttle. If you looked out the window of an airplane at just the right place and time last week, you could have seen something very unusual -- the space shuttle Endeavour launching to orbit.

Lighthouse and Meteor
8.01.2012

Named for a forgotten constellation, the Quadrantid Meteor Shower is an annual event for planet Earth's northern hemisphere skygazers. It usually peaks briefly in the cold, early morning hours of January 4. The shower's radiant point on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis.

A Waterspout in Florida
17.07.2013

What's happening over the water? Pictured above is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water. Waterspouts are spinning columns of rising moist air that typically form over warm water.

M31: The Andromeda Galaxy
30.07.2014

Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it.