Astronomy Picture of the Day

2013-02-28 Göran Strand

The alarmingly tall inhabitants of this small, snowy planet cast long shadows in bright moonlight. Of course, the snowy planet is actually planet Earth and the wide-angle mosaic, shown as a little planet projection, was recorded on February 25 ...

2013-02-27 Witta Priester

What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Known informally as Undulatus asperatus clouds, ...

2013-02-26

Does it rain on the Sun? Yes, although what falls is not water but extremely hot plasma. An example occurred in mid-July 2012 after an eruption on the Sun that produced both a Coronal Mass Ejection and a moderate solar flare. What was more ...

2013-02-25 Greg Gibbs

Sometimes the Moon is a busy direction. Last week, for example, our very Moon passed in front of the planet Jupiter. While capturing this unusual spectacle from New South Wales, Australia, a quick-thinking astrophotographer realized that a nearby ...

2013-02-24

The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The above image is ...

2013-02-23 Marat Ahmetvaleev

A meteoroid fell to Earth on February 15, streaking some 20 to 30 kilometers above the city of Chelyabinsk, Russia at 9:20am local time. Initially traveling at about 20 kilometers per second, its explosive deceleration after impact with the lower ...

2013-02-22

This remarkable self-portrait of NASA's Mars Curiosity Rover includes a sweeping panoramic view of its current location in the Yellowknife Bay region of the Red Planet's Gale Crater. The rover's flat, rocky perch, known as "John Klein", served as ...

2013-02-21 FIAAA

How would you change the course of an Earth-threatening asteroid? One possibility - a massive spacecraft that uses gravity as a towline - is illustrated in this artist's vision of a gravitational tractor in action. In the hypothetical scenario ...

2013-02-20

Why would clouds form a hexagon on Saturn? Nobody is sure. Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System. If Saturn's South Pole wasn't strange ...

2013-02-19 Juan Carlos Casado

Have you ever seen the planet Mercury? Because Mercury orbits so close to the Sun, it never wanders far from the Sun in Earth's sky. If trailing the Sun, Mercury will be visible low on the horizon for only a short while after sunset. If leading ...