Astronomy Picture Of the Day (APOD)
Micro-Quasar GRS1915 Puffs2.12.1997
On the far side of our Galaxy, gas clouds explode away from a small black hole. This might seem peculiar, as black holes are supposed to attract matter. But material falling toward a black hole collides and heats up, creating an environment similar to a quasar that is far from stable.
Orion: The Big Picture
1.12.1997
Orion is big. Some of the stars that form the constellation of Orion are part of a giant gas cloud complex that stretches over 100 light years and appears more than 50 times the diameter of the Moon.
Mercury: A Cratered Inferno
30.11.1997
Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. Mercury's diameter is about 4800 km, while the Moon's is slightly less at about 3500 km (compared with about 12,700 km for the Earth). But Mercury is unique in many ways.
Lasers in Eta Carinae
29.11.1997
Have you heard about the great LASER light show in the sky? A team led by K. Davidson (U. Michigan) and S. Johansson (U. Lund) discovered that the chaotically variable star Eta Carinae emits ultraviolet light in such a narrow band that it is most probably LASER light!
Beta Pictoris Revisited
28.11.1997
In the early 1980s, Beta Pictoris became one of the most important stars in the sky. Satellite and ground-based telescopic observations revealed the presence of a surrounding outer disk of material and an inner "clear" zone about the size of our solar system - strong evidence for the formation of planets.
Jupiter's Inner Moons
27.11.1997
The potato-shaped inner moons of Jupiter are lined-up in this mosaic "family portrait" of these tiny Jovian satellites. The individual images were recorded over the last year by NASA's Galileo spacecraft and are scaled to the moons' relative sizes.
Uranian Moons, Rings, And Clouds
26.11.1997
The giant planet Uranus is faint and featureless when viewed in visible light. But this pair of near-infrared mosaics from the Hubble Space Telescope's NICMOS camera reveals moons, rings, and clouds of this distant gas planet.
The Comet and the Galaxy
25.11.1997
The Moon almost ruined this photograph. During late March and early April, Comet Hale-Bopp passed nearly in front of the Andromeda Galaxy. Here the Great Comet of 1997 and the Great Galaxy in Andromeda were photographed together on March 24th. The problem was the brightness of the Moon.
Jet Near Light Speed
24.11.1997
Einstein's Special Theory of Relativity says that nothing can travel faster than the speed of light. Jets of protons and electrons that shoot away from objects such as quasars and black holes appear to travel at speeds approaching this maximum speed, though. Such jets carry tremendous energy and can ram straight through interstellar material.
Triton: Neptune's Largest Moon
23.11.1997
On October 10th, 1846, William Lassell was observing the newly discovered planet Neptune. He was attempting to confirm his observation, made just the previous week, that Neptune had a ring. But this time he discovered that Neptune had a satellite as well.
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