The Flight of Helios
31.08.2001

Solar-powered, remotely piloted, and flying at about 25 miles per hour, NASA's Helios aircraft, is pictured above at 10,000 feet in skies northwest of Kauai, Hawaii on August 13. This ultralight propeller driven aircraft, essentially a flying wing with 14 electric engines, was built by AeroVironment Inc.

Perseids of Summer
10.08.2001

Like falling stardust, cast off bits of comet Swift-Tuttle hurtle through the upper atmosphere about this time each year as planet Earth passes near the comet's orbital path. For the northern hemisphere, this...

A Year of Assessing Astronomical Hazards
31.12.2002

Could an asteroid destroy civilization on Earth? Mountain-sized space rocks could potentially impact the Earth causing global effects, and perhaps even be mistaken for a nuclear blast of terrestrial origin. Such large impacts are rare but have happened before. Modern telescopes have therefore begun to scan the skies for signs of approaching celestial hazards.

Springtime Comet Fever
20.03.1997

Today marks the Vernal Equinox, the first day of Spring for planet Earth's northern hemisphere. Despite recent attempts by other spectacular and dramatic celestial events to take center stage, Comet Hale-Bopp remains the most popular object in the sky (according to APOD access logs!) and is likely to make this spring memorable for many.

M27: Not A Comet
9.10.1998

While searching the skies above 18th century France for comets, astronomer Charles Messier diligently recorded this object as number 27 on his list of things which are definitely not comets. So what is it?

The Small Cloud of Magellan
17.06.2005

Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two celestial wonders easily visible for southern hemisphere skygazers are known as the Clouds of Magellan.

Supernova Remnant and Shock Wave
17.02.2006

A massive star ends life as a supernova, blasting its outer layers back to interstellar space. The spectacular death explosion is initiated by the collapse of what has become an impossibly dense stellar core. Pictured is the expanding supernova remnant Puppis A - one of the brightest sources in the x-ray sky.

Star Forming Region NGC 6357
20.12.2006

For reasons unknown, NGC 6357 is forming some of the most massive stars ever discovered. Near the more obvious Cat's Paw nebula, NGC 6357 houses the open star cluster Pismis 24, home to these tremendously bright and blue stars.

Cat s Eye Wide and Deep
29.06.2007

The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its more familiar outlines are seen in the the brighter central region of this impressive wide-angle view. But the composite image also combines many short and long exposures to reveal the nebula's extremely faint halo.

X Ray Stars of Orion
6.10.2007

The stars of Orion shine brightly in visible light in planet Earth's night sky. The constellation harbors the closest large stellar nursery, the Great Nebula of Orion, a mere 1,500 light-years away.