Ares 3 Landing Site: The Martian Revisited
16.05.2025

This close-up from the Mars Reconnaissance Orbiter's HiRISE camera shows weathered craters and windblown deposits in southern Acidalia Planitia. A striking shade of blue in standard HiRISE image colors, to the human eye the area would probably look grey or a little reddish.

A Sky Filled with Leonids
4.12.2001

In the early morning hours of November 19, amateur Chen Huang-Ming caught a sky filled with astronomical wonders. With his fisheye camera set up on Ho-Huan Mountain in Taiwan for a half-hour exposure, he started the above image a local time of 2:33 am.

Driving Toward a Sun Halo
13.06.2006

What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a large lens. In the above case, however, there are actually millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.

Teimareh Petroglyphs and Star Trails
12.07.2012

Engraved in rock, these ancient petroglyphs are abundant in the Teimareh valley, located in the Zagros Mountains of central Iran. They likely tell a tale of hunters and animals found in the middle eastern valley 6,000 years ago or more, etched by artists in a prehistoric age.

Surprising Comet ISON
30.11.2013

After failing to appear for Sun staring spacecraft at perihelion, its harrowing closest approach to the Sun, sungrazing Comet ISON was presumed lost. But ISON surprised observers yesterday as material still traveling along the comet's trajectory became visible and even developed an extensive fan-shaped dust tail.

A Total Eclipse at the End of the World
14.03.2015

Would you go to the end of the world to see a total eclipse of the Sun? If you did, would you be surprised to find someone else there already? In 2003, the Sun, the Moon, Antarctica, and two photographers all lined up in Antarctica during an unusual total solar eclipse.

Milky Way with Airglow Australis
3.09.2015

After sunset on September 1, an exceptionally intense, reddish airglow flooded this Chilean winter night skyscape. Above a sea of clouds and flanking the celestial Milky Way, the airglow seems to ripple and flow across the northern horizon in atmospheric waves.

APOD: 2024 April 29 Б Comet, Planet, Moon
28.04.2024

Three bright objects satisfied seasoned stargazers of the western sky just after sunset earlier this month. The most familiar was the Moon, seen on the upper left in a crescent phase. The rest of the Moon was faintly visible by sunlight first reflected by the Earth.

Arp 81: 100 Million Years Later
10.12.2003

From planet Earth, we view this strongly interacting pair of galaxies, cataloged as Arp 81, as they were only about 100 million years after their mutual closest approach. The havoc wreaked by gravity during...

Mapping Mars
18.03.1999

This month, the Mars Global Surveyor (MGS) spacecraft began its primary mission to the red planet. Orbiting about once every two hours at an altitude of over 200 miles, instruments onboard MGS now regularly explore the Martian surface and atmosphere.