Moon Occults Venus
21.06.2020

It may look like Earthrise, but it's actually Venus-set. Just after sunrise two days ago, both the Moon and Venus also rose. But then the Moon overtook Venus. In the featured image sequence centered on the Moon, Venus is shown increasingly angularly close to the Moon.

Galactic Center Flicker Indicates Black Hole
10.09.2001

Why would the center of our Galaxy flicker? Many astronomers believe the only credible answer involves a black hole. During observations of Sagittarius A* with the orbiting Chandra X-ray Observatory, the bright X-ray source at the very center of our Milky Way brightened dramatically for a few minutes.

THEMIS of Mars
2.11.2001

Not an ancient Greek goddess, THEMIS is modern acronese for THermal EMission Imaging System. Above is this remarkable instrument's premier infrared image of Mars, from the newly orbiting Mars Odyssey spacecraft. Taken...

Orionids Meteor Shower to Peak Tonight
21.10.1996

Tonight you might be able to see Halley's Comet again - or at least some pieces of it. It is widely thought that that the meteors from the Orionids meteor shower, which peaks tonight, are just small pieces of Halley's Comet falling to Earth.

Solar Wind And Milky Way
4.03.1997

The Sun is bright, so bright that it overwhelms the light from other stars even for most satellite-borne telescopes. But LASCO, a coronograph onboard the space-based SOHO Observatory, uses occulting disks to block the intense solar light and examine the tenuous, hot gases millions of miles above the Sun's surface.

Green and Black Auroras Over Norway
29.03.2006

What causes gaps between aurora curtains? These unusual gaps can make Research using data from four Cluster spacecraft orbiting the Earth has likely found the secret: auroral gaps, sometimes knows as black auroras, are actually anti-auroras. In normal auroras, electrons and/or predominantly negatively charged particles fall toward Earth along surfaces of constant magnetic field.

Bright Cliffs Across Saturns Moon Dione
5.09.2006

What causes the bright streaks on Dione? Recent images of this unusual moon by the robot Cassini spacecraft now orbiting Saturn are helping to crack the mystery. Close inspection of Dione's trailing hemisphere, pictured above, indicates that the white wisps are composed of deep ice cliffs dropping hundreds of meters.

Martian Dust Devil Trails
17.03.2000

Who's been marking up Mars? This portion of a recent high-resolution picture from the orbiting Mars Global Surveyor spacecraft shows twisting dark trails criss-crossing a relatively flat rippled region about 3 kilometers wide on the martian surface.

Shadow Of Phobos
5.11.1999

Hurtling through space above the Red Planet, potato-shaped Phobos completes an orbit of Mars in less than eight hours. In fact, since its orbital period is shorter than the planet's rotation period, Mars-based...

Io: The Prometheus Plume
11.02.2007

What's happening on Jupiter's moon Io? Two sulfurous eruptions are visible on Jupiter's volcanic moon Io in this color composite image from the robotic Galileo spacecraft that orbited Jupiter from 1995 to 2003.