APOD: 2024 July 9 Б Noctilucent Clouds over Florida
9.07.2024

These clouds are doubly unusual. First, they are rare noctilucent clouds, meaning that they are visible at night -- but only just before sunrise or just after sunset. Second, the source of these noctilucent clouds is actually known.

Callisto Full Face
20.01.2002

Callisto's surface shows its age. While probably formed at the same time as Io, the difference between the surfaces of these two moons of Jupiter could hardly be greater. Io's surface is young, shows practically no impact craters, and is continually being repaved by the lava exploding from its many large volcanoes

Quaoar: Large Asteroid in the Outer Solar System
9.10.2002

Asteroids almost as large as planets are still being discovered in our own Solar System. Recently an asteroid more than half the size of Pluto was found orbiting at a distance only a little further than the Solar System's most distant planet.

Mars Volcano Apollinaris Patera
13.05.1999

Dwarfed by Olympus Mons and the other immense shield volcanos on Mars, Apollinaris Patera rises only 3 miles or so into the thin martian atmosphere, but bright water-ice clouds can be still be seen hovering around its summit.

Dark Slope Streaks Split on Mars
18.07.2018

What is creating these dark streaks on Mars? No one is sure. Candidates include dust avalanches, evaporating dry ice sleds, and liquid water flows. What is clear is that the streaks occur through light surface dust and expose a deeper dark layer.

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.