NGC 4697: X Rays from an Elliptical Galaxy
17.06.2002

The many bright, point-like sources in this Chandra Observatory x-ray image lie within NGC 4697, an elliptical galaxy some 40 million light-years away towards Virgo. Like other normal elliptical galaxies, NGC 4697 is a spherical ensemble of mainly older, fainter, low mass stars, with little star forming gas and dust compared to spiral galaxies.

VAR
1.07.2011

In the 1920s, examining photographic plates from the Mt. Wilson Observatory's 100 inch telescope, Edwin Hubble determined the distance to the Andromeda Nebula, decisively demonstrating the existence of other galaxies far beyond the Milky Way.

Bright Supernova in M82
24.01.2014

Astronomers really don't find supernovae by looking for the arrows. But in this image taken January 23rd, an arrow does point to an exciting, new supernova, now cataloged as SN 2014J, in nearby bright galaxy M82.

X-Rays from the Galactic Plane
14.08.2001

In February 2000, the orbiting Chandra X-ray Observatory spent 27 hours staring into the plane of our Milky Way galaxy. Its target was a spot in the small constellation Scutum, within the Milky Way's zone of avoidance where galactic gas and dust clouds block visible light, making a poor window for optical telescopes.

Lyman Alpha Blob
2.07.2009

Dubbed a Lyman-alpha blob, an enormous cloud of hydrogen gas spans several hundred thousand light-years in this remarkable image (left), a composite of x-ray, optical, and infrared data from space and ground based observatories.

21st Century M101
13.07.2012

One of the last entries in Charles Messier's famous catalog, big, beautiful spiral galaxy M101 is definitely not one of the least. About 170,000 light-years across, this galaxy is enormous, almost twice the size of our own Milky Way Galaxy.

NGC 6357: The Lobster Nebula
1.11.2022

Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure. Cataloged as NGC 6357, the Lobster Nebula houses the open star cluster Pismis 24 near its center -- a home to unusually bright and massive stars.

The Tarantula Zone
8.03.2024

The Tarantula Nebula, also known as 30 Doradus, is more than a thousand light-years in diameter, a giant star forming region within nearby satellite galaxy the Large Magellanic Cloud. About 180 thousand light-years away, it's the largest, most violent star forming region known in the whole Local Group of galaxies.

How Much is That Comet in the Window?
27.03.1996

The above true-color photo taken March 25th shows Comet Hyakutake passing below the stars of the Big Dipper. Many astronomy enthusiasts delight in helping people in their local community see the comet. Both Jerry Bonnell and I (RJN) from APOD have been so inclined - both now and when Comet Halley came by in 1986.

Mizar Binary Star
19.02.1997

Mizar (sounds like "My Czar") is a binary star. In fact, most stars are binary stars. In a binary star system, each star of the pair follows an elliptical orbital path. Mutual gravity causes...