APOD: 2025 July 15 Б Collapse in Hebes Chasma on Mars
15.07.2025

What's happened in Hebes Chasma on Mars? Hebes Chasma is a depression just north of the enormous Valles Marineris canyon. Since the depression is unconnected to other surface features, it is unclear where the internal material went.

Layered Hills in Arabia Terra on Mars
15.08.2010

Why are some hills on Mars so layered? The answer is still under investigation. Clearly, dark windblown sand surrounds outcropping of light sedimentary rock across the floor of crater Arabia Terra. The light rock clearly appears structured into many layers, the lowest of which is likely very old.

Layered Hills on Mars
24.12.2003

Why are some hills on Mars so layered? The answer is still under investigation. Clearly, dark windblown sand surrounds outcropping of light sedimentary rock across the floor of crater Arabia Terra. The light rock clearly appears structured into many layers, the lowest of which is likely very old.

Spirit Rover on Mars Imaged from Orbit
6.12.2006

If you have the right equipment, you can see the Spirit rover currently rolling across Mars. The right equipment, however, is currently limited to the High Resolution Imaging Science Experiment onboard the Mars Reconnaissance Orbiter (MRO). MRO arrived at Mars in March and just started science observations of the red planet last month.

Collapse in Hebes Chasma on Mars
28.05.2017

What's happened in Hebes Chasma on Mars? Hebes Chasma is a depression just north of the enormous Valles Marineris canyon. Since the depression is unconnected to other surface features, it is unclear where the internal material went.

Oceans Under Jupiters Callisto
31.07.2001

Why does Jupiter's moon Callisto alter the magnetic field of Jupiter in its vicinity? Callisto itself does not have a strong magnetic field. One possible answer is that Callisto harbors sub-surface oceans of electrically conducting salt-water. This hypothesis was bolstered recently by a new analysis of how Callisto creates and dissipates heat.

Collapse in Hebes Chasma on Mars
12.08.2014

What's happened in Hebes Chasma on Mars? Hebes Chasma is a depression just north of the enormous Valles Marineris canyon. Since the depression is unconnected to other surface features, it is unclear where the internal material went.

18 Miles From Deimos
22.12.1996

Diminutive Deimos is the smallest of the two tiny Moons of Mars. Potato shaped and barely 6 miles wide this asteroid-like body was visited by the Viking 2 orbiter in 1977. This image was made when the spacecraft approached to within 18 miles of Deimos' surface.

Halley s Nucleus: An Orbiting Iceberg
5.08.2000

What does a comet nucleus look like? Formed from the primordial stuff of the solar system, it is thought to resemble a very dirty iceberg. But for active comets, telescopic images only reveal the surrounding cloud of gas and dust, the comet's coma, and the characteristic cometary tails.

Comet Halleys Nucleus: An Orbiting Iceberg
4.01.2010

What does a comet nucleus look like? Formed from the primordial stuff of the Solar System, comet nuclei were thought to resemble very dirty icebergs. But ground-based telescopes revealed only the surrounding cloud of gas and dust of active comets nearing the Sun, clearly resolving only the comet's coma, and the characteristic cometary tails.