Ganymede: The Largest Moon in the Solar System
20.06.2000

If Ganymede orbited the Sun, it would be considered a planet. The reason is that Jupiter's moon Ganymede is not only the largest moon in the Solar System, it is larger than planets Mercury and Pluto.

Emission and Reflection in NGC 6559
23.10.2001

Bright gas and dark dust permeate the space between stars in a nebula known as NGC 6559. The gas, primarily hydrogen, is responsible for the diffuse red glow of the emission nebula. As energetic...

Noctilucent Clouds
15.06.2003

Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above.

Jupiter s Impact Scar
23.07.2009

In July of 1994 pieces of Comet Shoemaker-Levy 9 collided with planet Jupiter. The explosive impacts sent plumes of debris high into the Jovian atmosphere creating dark markings or scars, visible for a time against the cloud bands.

APOD: 2023 July 31 Б Phobos over Mars
30.07.2023

Why is Phobos so dark? Phobos, the largest and innermost of the two Martian moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.

APOD: 2024 March 31 Б Total Solar Eclipse Below the Bottom of the World
30.03.2024

In late 2021 there was a total solar eclipse visible only at the end of the Earth. To capture the unusual phenomenon, airplanes took flight below the clouded seascape of Southern Ocean. The featured...

The North America Nebula
6.06.1996

Here's a familiar shape in an unfamiliar location! This emission nebula is famous partly because it resembles Earth's North American Continent. To the right of the North America Nebula is a less luminous Pelican Nebula. Let's be grateful that pelicans aren't really that large!

M7: Open Star Cluster in Scorpius
12.09.2012

M7 is one of the most prominent open clusters of stars on the sky. The cluster, dominated by bright blue stars, can be seen with the naked eye in a dark sky in the tail of the constellation of the Scorpion (Scorpius).

The Gegenschein Over Chile
7.05.2008

Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles.

APOD: 2024 January 1 Б NGC 1232: A Grand Design Spiral Galaxy
31.12.2023

Galaxies are fascinating not only for what is visible, but for what is invisible. Grand spiral galaxy NGC 1232, captured in detail by one of the Very Large Telescopes, is a good example.