Ash and Lightning above an Icelandic Volcano
12.05.2019

Why did a picturesque volcanic eruption in Iceland create so much ash? Although the large ash plume was not unparalleled in its abundance, its location was particularly noticeable because it drifted across such well-populated areas.

Saturns Rings Seen Sideways
18.10.1998

Saturn's rings are actually very thin. This picture from the Hubble Space Telescope was taken on August 6, 1995 when the rings lined up sideways as seen from Earth. Saturn's largest moon Titan is seen on the left, and Titan's shadow can be seen on Saturn's cloud tops!

Aurora and Volcanic Light Pillar
23.09.2014

That's no sunset. And that thin red line just above it -- that's not a sun pillar. The red glow on the horizon originates from a volcanic eruption, and the red line is the eruption's reflection from fluttering atmospheric ice crystals. This unusual volcanic light pillar was captured over Iceland earlier this month.

Comet 45P Passes Near the Earth
12.02.2017

A large snowball has just passed the Earth. Known as Comet 45P/HondaMrkosPajduАkovА", or 45P for short, the comet came 10 times closer to Earth yesterday than the Earth ever gets to the Sun. During this passage, the comet was photographed sporting a thin ion tail and a faint but expansive green coma.

APOD: 2025 July 6 Б The Spiral North Pole of Mars
6.07.2025

Why is there a spiral around the North Pole of Mars? Each winter this pole develops a new outer layer about one meter thick composed of carbon dioxide frozen out of the thin Martian atmosphere. This fresh layer is deposited on a water-ice layer that exists year round.

Methane Bubbles Frozen in Lake Baikal
18.12.2018

What are these bubbles frozen into Lake Baikal? Methane. Lake Baikal, a UNESCO World Heritage Site in Russia, is the world's largest (by volume), oldest, and deepest lake, containing over 20% of the world's fresh water.

Neptune at Night
9.11.2024

Ice giant Neptune is faint in Earth's night sky. Some 30 times farther from the Sun than our fair planet, telescopes are needed to catch a glimpse of the dim and distant world. This dramatic view of Neptune's night just isn't possible for telescopes in the vicinity of planet Earth though.

Comet Hale-Bopp Over Val Parola Pass
27.05.2001

Comet Hale-Bopp became much brighter than any surrounding stars. It was seen even over bright city lights. Out away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains surrounding Cortina d'Ampezzo, Italy.

Stereo Saturn
7.09.2002

Get out your red/blue glasses and launch yourself into this stereo picture of Saturn! The picture is actually composed from two images recorded weeks apart by the Voyager 2 spacecraft during its visit to the Saturnian System in August of 1981.

Earth, Clouds, Sky, Comet
3.04.1997

Does a comet's dust tail always orbit behind it? Since comets rotate, they shed gas and dust in all directions equally. Small ice and dust particles expelled by the comet, however, are literally pushed around by sunlight. The smaller the particle, the greater the effect.