Two Million Galaxies
7.10.2007

Our universe is filled with galaxies. Galaxies -- huge conglomerations of stars, gas, dust -- and mysterious dark matter are the basic building blocks of the large-scale universe. Although distant galaxies move away from each other...

Milky Way Over Crater Lake with Airglow
19.06.2013

How many different astronomical phenomena have come together to create the above vista? Several. First, in the foreground, is Crater Lake -- a caldera created by volcanism on planet Earth about 7,700 years ago. Next, inside the lake, is water.

Ganymede from Juno
14.06.2021

What does the largest moon in the Solar System look like? Jupiter's moon Ganymede, larger than even Mercury and Pluto, has an icy surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges.

New Horizons at Jupiter
4.12.2003

Headed for the first close-up exploration of the Pluto-Charon system and the icy denizens of the Kuiper belt, NASA's New Horizons spacecraft is pictured here in an artist's vision of the robot probe outward bound.

Rumors of a Strange Universe
27.02.2004

Only a few short years ago, when the APOD editors were in graduate school, the pervasive, cosmic Dark Energy was not even seriously discussed. Of course, it now appears that this strange energy dominates the cosmos (as well as lectures on cosmology) and provides a repulsive force accelerating the large scale expansion of the Universe.

Fornax Cluster in Motion
24.09.2004

Reminiscent of popular images of the lovely Pleiades star cluster that lies within our own Milky Way Galaxy, this false-color x-ray view actually explores the center of a much more extended cosmic family -- the Fornax cluster of galaxies some 65 million light-years away.

Parker vs Perseid
16.08.2018

The brief flash of a bright Perseid meteor streaks across the upper right in this composited series of exposures made early Sunday morning near the peak of the annual Perseid meteor shower.

APOD: 2026 March 18 Б Cygnus and the Solitary Tree
18.03.2026

A lone tree stands in a quiet meadow in Guadalajara, Spain, silhouetted against the Cygnus region rising above like flames in the night sky. This deep night skyscape is a composite of exposures that reveals a range of brightness and color human eyes can't quite see on their own.

Dark Matter, X rays, and NGC 720
26.10.2002

Elliptical galaxy NGC 720 is enveloped in a cosmic cloud of x-ray emitting gas. Seen in this false color image from the Chandra X-ray Observatory, the extreme temperature of the gas - about 7 million...

Farther Along
6.05.2011

What is humanity's most distant spacecraft? Launched in 1977, Voyager 1 now holds that distinction at 17.5 billion kilometers from the Sun. That corresponds to 16 light-hours or 117 Astronomical Units (AU). This...