A High Energy Fleet
24.11.2000

Like a fleet of futuristic starcruisers, NASA's highly successful series of High Energy Astrophysical Observatory (HEAO) spacecraft appear poised over planet Earth. Labeled A, B, and C in this vintage illustration, the spacebased telescopes were known as HEAO-1, HEAO-2, and HEAO-3 respectively.

Rumors of a Strange Universe
26.02.2004

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.

Sunset Over Gusev Crater
20.06.2005

What would it be like to see a sunset on Mars? To help find out, the robotic rover Spirit was deployed last month to park and serenely watch the Sun dip below the distant lip of Gusev crater. It was a tough job, but some robot had to do it.

Galaxy Cluster Abell 1689 Deflects Light
17.09.2013

It is one of the most massive objects in the visible universe. In this view from the Hubble Space Telescope's Advanced Camera for Surveys, Abell 1689 is seen to warp space as predicted by Einstein's theory of gravity -- deflecting light from individual galaxies which lie behind the cluster to produce multiple, curved images.

Spin up of a Supermassive Black Hole
12.03.2013

How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown.

First Horizon Scale Image of a Black Hole
10.04.2019

What does a black hole look like? To find out, radio telescopes from around the Earth coordinated observations of black holes with the largest known event horizons on the sky. Alone, black holes are just black, but these monster attractors are known to be surrounded by glowing gas.

The Supermassive Black Holes of NGC 6240
27.11.2002

The Hubble optical image on the left shows NGC 6240 in the throes of a titanic galaxy - galaxy collision 400 million light-years away. As the cosmic catastrophe plays out, the merging galaxies spew forth distorted tidal tails of stars, gas, and dust and undergo frantic bursts of star formation.

At the Center of the Milk Way
18.10.2002

At the center of our Milky Way Galaxy lies a black hole with over 2 million times the mass of the Sun. Once a controversial claim, this astounding conclusion is now virtually inescapable and based on observations of stars orbiting very near the galactic center.

A Galactic Cloud of Antimatter
1.05.1997

The center of our Milky Way Galaxy is full of surprises. Its latest spectacular is a mysterious cloud glowing in gamma rays produced by annihilating antimatter particles! Star Trek fans are all too familiar...

The Very Large Array at Moonset
8.10.2020

An inspirational sight, these giant dish antennas of the Karl G. Jansky Very Large Array (VLA) rise above the New Mexico desert at moonset. Mounted on piers but transportable on railroad tracks to change...