Extraordinary Solar Halos
21.12.2018

Welcome to the December Solstice, the first day of winter in planet Earth's northern hemisphere and summer in the south. To celebrate, consider this extraordinary display of beautiful solar ice halos! More common than rainbows, simple ice halos can be easy to spot, especially if you can shade your eyes from direct sunlight.

A Sun Halo Beyond Stockholm
10.01.2011

What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a large lens. In the above case, however, there are actually millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.

Young Martian Terrain
1.08.2001

What caused the pits, ridges, and gullies on otherwise smooth Martian terrain? One hypothesis is water. The lack of craters at this mid-latitude location indicates that the terrain is quite young by geological standards, perhaps only 100,000 years old.

The Lost World of Lake Vida
4.04.2004

A lake hidden beneath 19 meters of ice and gravel has been found near the bottom of the world that might contain an ecosystem completely separate from our own. In a modern version...

Shadows and Plumes Across Enceladus
4.08.2014

Why does Enceladus have ice plumes? The discovery of jets spewing water vapor and ice was detected by the Saturn-orbiting Cassini spacecraft in 2005. The origin of the water feeding the jets, however, remained a topic of research.

Lunar Halo over Snowy Trees
1.02.2021

Have you ever seen a halo around the Moon? This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens.

Voyage of an Antarctic Iceberg
23.02.2005

What if part of New York broke off and slammed into New Jersey? Both being anchored land masses, that is unlikely to happen, but an event of that size scale did occur off the Antarctic coast over the last three months.

Sun Halo at Winter Solstice
14.01.2002

Sometimes it looks like the Sun is being viewed through a large lens. In the above case, however, there are actually millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.

APOD: 2025 October 12 Б All the Water on Europa
12.10.2025

How much of Jupiter's moon Europa is made of water? No one is sure, but probably a lot. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa possesses a deep, global ocean of liquid water beneath a layer of surface ice.

Seventeen Hundred Kilometers Above Enceladus
5.11.2008

Above is one of the closest pictures yet obtained of Saturn's ice-spewing moon Enceladus. The image was taken from about 1,700 kilometers up as the robotic Cassini spacecraft zoomed by the fractured ice ball last week.