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.

A Digital Sunset Over Europe and Africa
23.03.2003

No single spacecraft or astronaut took this picture. It is a digital composite of archived images taken over many orbits by several Earth-orbiting satellites. Similar images can be digitally stitched together for any Earth location by John Walker's Earth and Moon Viewer website.

APOD: 2023 June 12 Б The Largest Satellites of Earth
11.06.2023

WhatБs that near the Moon? ItБs the International Space Station (ISS). Although the ISS may appear to be physically near the Moon, it is not Б it is physically near the Earth.

APOD: 2025 February 2 Б Comet G3 ATLAS Disintegrates
1.02.2025

What's happening to Comet G3 ATLAS? After passing near the Sun in mid-January, the head of the comet has become dimmer and dimmer. By late January, Comet C/2024 G3 (ATLAS) had become a headless wonder -- even though it continued to show impressive tails after sunset in the skies of Earth's Southern Hemisphere.

John Glenn: Discovery Launch
29.10.1998

At left, the Space Shuttle Discovery waits in darkness on Kennedy Space Center's launch pad 39B. At right, on Thursday October 29, Discovery blasts through a bright afternoon sky returning Senator John Glenn to space over 36 years after he became the first American in orbit.

Saturnian Moon and Rings
18.04.2005

When can a robot produce art? When it glides past the rings of Saturn, for one. As the robot spacecraft Cassini orbiting Saturn crossed outside the famous photogenic ring plane of the expansive planet, the rings were imaged from the outside, nearly edge on, and in the shadow of Saturn.

A Visit from Atlantis
28.06.2007

This remarkable image of the space shuttle orbiter Atlantis docked with the International Space Station (ISS) was taken at a range of 190 nautical miles. To record the fast moving pair, last week astronomers...

Ganymede: A Really Groovy Moon
11.07.1996

Ganymede's surface is a wrinkled mess. As large ice-sheets shift on the moon's surface, parts of the surface buckle causing high ridges, deep furrows, and parallel grooves. This photo, taken by the Galileo spacecraft currently orbiting Jupiter, was released yesterday. The large circular feature near the picture bottom is a large impact crater.

GRB 990510: Another Unusual Gamma Ray Burst
26.05.1999

Another huge explosion has lit up the universe, and astronomers are studying it as best they can before the light fades away. Two weeks ago, the BATSE instrument on the orbiting NASA Great Observatory Compton detected unusually bright flashes of gamma-rays from a point deep in the southern sky.

Launch of a Delta IV Heavy
13.12.2010

It is the tallest rocket in active use. The Delta IV Heavy is the largest of the Delta series, packing the punch of three rocket boosters instead of the usual one. The resulting rocket...