Particle Sizes in Saturns Rings
25.05.2005

What size particles compose Saturn's rings? To help find out, the robot Cassini spacecraft now orbiting Saturn broadcast radio waves of three different wavelengths right through the rings to Earth earlier this month.

Angry Sun Erupting
14.03.2012

It's one of the baddest sunspot regions in years. Active Region 1429 may not only look, to some, like an angry bird -- it has thrown off some of the most powerful flares and coronal mass ejections of the current solar cycle.

White Boat Rock on Mars
25.02.2004

What caused this rock to have an unusual shape? Earlier this month the robot Spirit rover on Mars stopped to examine a rock dubbed "white boat", named for its unusually light color and shape.

Reflection Nebula M78
24.04.2000

An eerie blue glow and ominous columns of dark dust highlight M78, a bright reflection nebula in the constellation of Orion. The dust not only absorbs light, but also reflects the light of several bright blue stars that formed recently in the nebula.

Two Hours Before Neptune
8.08.2010

Two hours before closest approach to Neptune in 1989, the Voyager 2 robot spacecraft snapped this picture. Clearly visible for the first time were long light-colored cirrus-type clouds floating high in Neptune's atmosphere. Shadows of these clouds can even be seen on lower cloud decks.

Two Hours Before Neptune
5.10.1999

Two hours before closest approach to Neptune in 1989, the Voyager 2 robot spacecraft snapped this picture. Clearly visible for the first time were long light-colored cirrus-type clouds floating high in Neptune's atmosphere. Shadows of these clouds can even be seen on lower cloud decks.

NGC 1512: A Panchromatic View
6.06.2001

This spectacular color picture of the core of barred spiral galaxy NGC 1512 (bottom panel) is a composite of the seven Hubble Space Telescope images arrayed along the top. Each top panel image was made with a filter and camera sensitive to a different wavelength band in the electromagnetic spectrum.

A Scorpius Sky Spectacular
4.05.2014

If Scorpius looked this good to the unaided eye, humans might remember it better. Scorpius more typically appears as a few bright stars in a well-known but rarely pointed out zodiacal constellation. To get a spectacular image like this, though, one needs a good camera, color filters, and a digital image processor.

Identify this Phenomenon
13.09.2004

What caused this ring of colors? At the time of this writing, MIT Physics Professor Walter Lewin had yet to find someone who can give the correct explanation. Not students. Not colleagues. Not APOD editors. He wonders how the astute readers of APOD will do. Can you match wits with Professor Lewin?

From California to the Pleiades
22.11.2013

An astronomical trip from the California Nebula to the Pleiades star cluster would cover just 12 degrees across planet Earth's night sky. That's equivalent to the angular extent of 25 Full Moons, as your telescope sweeps over the borders of the constellations Perseus and Taurus.