Leonids from Leo
8.12.1998

Is Leo leaking? Leo, the famous sky constellation visible on the left of the above all-sky photograph, appears to be the source of all the meteors seen in this year's Leonids Meteor Shower.

Martian Moon Phobos from Mars Express
1.12.2010

Why is Phobos so dark? Phobos, the largest and innermost of 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.

Martian Moon Phobos from Mars Express
8.11.2020

Why is Phobos so dark? Phobos, the largest and innermost of 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.

Chandra X Ray Telescope
27.07.1999

Wrapped in protective blankets and mounted atop an Inertial Upper Stage (IUS) rocket, the Chandra X-ray Telescope is seen in this wide-angle view before launch snuggled into the space shuttle Columbia's payload bay.

Phobos from Mars Express
17.03.2010

Why is this small object orbiting Mars? The origin of Phobos, the larger of the two moons orbiting Mars, remains unknown. Phobos and Deimos appear very similar to C-type asteroids, yet gravitationally capturing such asteroids, circularizing their orbits, and dragging them into Mars' equatorial plane seems unlikely.

Phobos Over Mars
13.03.1999

Hurtling through space a mere 3,000 miles above the Martian surface, the diminutive moon Phobos (below and left of center) was imaged against the backdrop of a large shield volcano by the Viking 2 Orbiter in 1977.

The Seasons of Saturn
2.07.2001

Soon it will be winter in Saturn's northern hemisphere. Since Saturn is tilted in its orbit around the Sun, it has seasons just like the Earth. When a hemisphere is tilted so that the Sun passes more directly overhead, summer occurs. Half an orbit later -- about 15 (Earth) years for Saturn -- winter occurs.

Phobos Over Mars
15.10.1996

Hurtling through space a mere 3,000 miles above the Martian surface, the diminutive moon Phobos (below and left of center) was imaged against the backdrop of a large shield volcano by the Viking 2 Orbiter in 1977.

Boosting Compton
6.06.1997

Even great observatories need a boost from time to time -- including the orbiting Compton Gamma-Ray Observatory. Sparkling reflections and the bright limb of the Earth are visible in this 1991 window view of Compton's release into orbit by the crew of the Space Shuttle Atlantis.

Moon Phases in 2021
11.01.2021

What will the Moon phase be on your birthday this year? It is hard to predict because the Moon's appearance changes nightly. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible.