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Astronomy Picture Of the Day (APOD)
Aurora and Orion
19.03.1999
Looking toward the south from low Earth orbit, the crew of the Space Shuttle Endeavor made this stunning time exposure of the Aurora Australis or southern lights in April of 1994. Aurora are visible at high northern latitudes as well, with the northern lights known as Aurora Borealis.
Mapping Mars
18.03.1999
This month, the Mars Global Surveyor (MGS) spacecraft began its primary mission to the red planet. Orbiting about once every two hours at an altitude of over 200 miles, instruments onboard MGS now regularly explore the Martian surface and atmosphere.
Messier Marathon
17.03.1999
Gripped by an astronomical spring fever, this week many amateur stargazers embark on a Messier Marathon. The Vernal Equinox occurs Saturday, March 20, marking the first day of Spring for the Northern Hemisphere.
Ice Fishing for Cosmic Neutrinos
16.03.1999
In 1996, scientists melted a hole in the bottom of the world. In fact, several holes have been melted near the South Pole, and they are now being used as astronomical observatories. Astronomers with the Antarctic Muon and Neutrino Detector Array (AMANDA) lower into each vertical lake a string knotted with basketball-sized light detectors.
Sigmoids Predict Solar Eruptions
15.03.1999
On the Sun, S marks the spot. Solar explosions have been discovered to explode preferentially from regions marked with this letter. The surface of the quiet Sun is a maze of hot gas and flowing magnetic fields. When two regions of high magnetic field strength approach each other, they typically pass uneventfully.
Happy Face Crater on Mars
14.03.1999
Even Mars can put on a happy face. The Martian crater Galle has internal markings reminiscent of a smiley face symbol. Such markings were originally discovered in the late 1970s in pictures taken by the Viking Orbiter. A large meteor impacted the Martian surface to form the crater.
The Comet and the Galaxy
13.03.1999
The Moon almost ruined this photograph. During late March and early April 1997, 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 1997 March 24th. The problem was the brightness of the Moon.
Phobos Over Mars
12.03.1999
Hurtling through space a mere 3,000 miles above the Martian surface, the diminutive moon Phobos (below and left of center) was imaged against the backdrop of a large shield volcano by the Viking 2 Orbiter in 1977.
Hydrogen, Helium, and the Stars of M10
11.03.1999
Stars like the Sun use hydrogen for fuel, "burning" hydrogen into helium at their cores through nuclear fusion. But what happens when that hydrogen runs out? For a while, hydrogen burns in a shell surrounding the stellar core and the star expands to become a red giant.
5 Million Miles From Io
10.03.1999
Twenty years ago this month, NASA's Voyager 1 spacecraft flew past Jupiter and its moons. This sharp picture of moon Io against a background of gas giant Jupiter's diffuse swirling cloud bands was recorded by Voyager's camera from a distance of about 5 million miles.
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