Rhea: Saturn's Second Largest Moon
14.10.1995

Rhea is the second largest moon of Saturn, behind Titan, and the largest without an atmosphere. It is composed mostly of water ice, but has a small rocky core. Rhea's rotation and orbit are locked together (just like Earth's Moon) so that one side always faces Saturn.

Leonid Fireball over Tenerife
22.11.2011

Historically active, this year's Leonid meteor shower was diminished by bright moonlight. Still, faithful night sky watchers did see the shower peak on November 18 and even the glare of moonlight didn't come close to masking this brilliant fireball meteor.

MAVEN at Mars
26.09.2014

Launched on November 18, 2013, the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft completed its interplanetary voyage September 21, captured into a wide, elliptical orbit around Mars. MAVEN's imaging ultraviolet spectrograph has already...

An ALMA Telescope Array Time Lapse
26.05.2014

It is the most expensive and complex ground-based astronomy project ever -- what will it see tonight? The Atacama Large Millimeter Array (ALMA) project consists of 66 dishes, many the size of a small house, situated in the high altitude Atacama Desert in Northern Chile.

The Perseid Meteor Shower
9.08.1996

From a radiant point in the constellation of Perseus, Comet Swift-Tuttle presents -- The Perseid Meteor Shower -- coming to your night sky this weekend! A bookish E. C. Herrick of New Haven, Connecticut correctly suspected in 1837 that this meteor shower was an annual event.

APOD: 2023 August 8 Б Moon Meets Jupiter
8.08.2023

What's that below the Moon? Jupiter -- and its largest moons. Many skygazers across planet Earth enjoyed the close conjunction of Earth's Moon passing nearly in front of Jupiter in mid-June. The featured image is a single exposure of the event taken from MorцЁn de la Frontera, Spain.

Comet 46P Wirtanen
15.11.2018

Periodic Comet 46P/Wirtanen is now the brightest comet in the night sky, but too faint to be seen by eye. From dark sky sites it could just become naked-eye visible though, as it's 5.4 year long looping orbit takes it closest to Earth and the Sun in mid December.

APOD: 2024 August 4 Б Gaia: Here Comes the Sun
4.08.2024

What would it look like to return home from outside our galaxy? Although designed to answer greater questions, data from ESA's robotic Gaia mission is helping to provide a uniquely modern perspective on humanity's place in the universe.

Alicante Beach Moonrise
19.07.2014

In this beach and skyscape from Alicante, Spain, July's Full Moon shines in the dark blue twilight, its reflection coloring the Mediterranean waters. Near the horizon, the moonlight is reddened by its long...

Name This Martian Robot
26.11.2002

NASA will launch two robots to Mars next year and you can help name them. The Mars Exploration Rovers are scheduled for launch on or near this coming June, when Mars and Earth are relatively close in their orbits.