Ninety Gravitational Wave Spectrograms and Counting
7.12.2021

Every time two massive black holes collide, a loud chirping sound is broadcast out into the universe in gravitational waves. Humanity has only had the technology to hear these unusual chirps for the past seven years, but since then we have heard about 90 -- during the first three observing runs.

The Hubble Ultra Deep Field
9.03.2004

The above picture will be replaced later today (between 9 and 10 am EST) by the newly released Hubble Ultra Deep Field (HUDF). The HUDF is expected to be the deepest image of the universe ever taken in visible light.

Unusual Giant Galaxy NGC 1316
16.08.2000

Can unusual giant galaxy NGC 1316 help calibrate the universe? Quite possibly -- if it turns out this atypical galaxy is composed of typical stars. NGC 1316, pictured above, is most obviously strange because...

POX 186: Not So Long Ago
3.01.2003

Not so long ago and not so far, far away, a galaxy was born. Seen in this Hubble Space Telescope image, the island universe of stars, gas, and dust cataloged as POX 186 is a mere 68 million light-years distant toward an uncrowded region in the constellation Virgo.

Boosting Compton
6.06.1997

Even great observatories need a boost from time to time -- including the orbiting Compton Gamma-Ray Observatory. Sparkling reflections and the bright limb of the Earth are visible in this 1991 window view of Compton's release into orbit by the crew of the Space Shuttle Atlantis.

Keck: The Largest Optical Telescope
15.07.1996

In buildings eight stories tall rest mirrors ten meters across that are slowly allowing humanity to map the universe. Alone, each is the world's largest optical telescope: Keck. Together, the twin Keck telescopes have the resolving power of a single telescope 90-meter in diameter, able to discern sources just milliarcseconds apart.

The VLT Interferometric Array
9.03.1999

The Very Large Telescope (VLT) Interferometric Array will be able to act as individual telescopes or as one huge telescope. Of the four planned VLTs in Chile, two have now reached completion. The first VLT to operate is visible on the left of the above photograph and was recently given the name Antu.

APOD: 2026 January 7 Б Simeis 147: The Spaghetti Nebula Supernova Remnant
7.01.2026

Its popular nickname is the Spaghetti Nebula. Officially cataloged as Simeis 147 and Sharpless 2-240, it is easy to get lost following the looping and twisting filaments of this intricate supernova remnant. Seen toward...

Chandra Deep Field
12.10.2002

Officially the Chandra Deep Field - South, this picture represents the deepest ever x-ray image of the Universe. One million seconds of accumulated exposure time with the orbiting Chandra X-ray Observatory went in to its making.

NGC 4414: A Telling Spiral
9.06.1999

How far away is this galaxy? Cosmologists the world over have been working hard to find out. Spiral galaxy NGC 4414 contains many Cepheid variable stars that oscillate in a way that allows astronomers to estimate their distance.