Anemic Spiral NGC 4921 from Hubble
14.05.2019

How far away is spiral galaxy NGC 4921? It's surpringly important to know. Although presently estimated to be about 300 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe.

Gamma Ray Earth and Sky
6.12.2013

For an Earth-orbiting gamma-ray telescope, Earth is actually the brightest source of gamma-rays, the most energetic form of light. Gamma-rays from Earth are produced when high energy particles, cosmic rays from space, crash into the atmosphere.

Near the Nucleus of Hyakutake
27.03.1996

NASA's Hubble Space Telescope captured this image of the near-nuclear region of Comet Hyakutake on March 25 as the comet approached within 9.3 million miles of the Earth. It covers a relatively "small" 2,000 mile wide area with the sunward direction toward the lower right (tailward is upper left).

A Cosmic Snowball
30.05.1997

Like cosmic snowballs, fluffy comet-like objects the size of houses and composed mostly of water-ice, may be pummeling planet Earth 5 to 30 times a minute. This controversial theory was originally proposed in 1986 by Dr. Louis Frank (U. Iowa) based on data from NASA's Dynamics Explorer 1.

25 Years Ago: Vikings on Mars
21.07.2001

On July 20, 1976, NASA's Viking 1 lander become the first spacecraft to land on Mars, followed weeks later by its twin robot explorer, the Viking 2 lander. Operating on the Martian surface...