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Astronomy Picture Of the Day (APOD)
Brown Dwarf Gliese 229B
23.03.1999
The spot near the bottom is an image of an unusual type of object: a brown dwarf. A brown dwarf is sometimes called a "failed star" because it does not have enough mass to shine by nuclear fusion.
A Chamaeleon Sky
22.03.1999
A photogenic group of nebulae can be found in Chamaeleon, a constellation visible predominantly in skies south of the Earth's equator. Towards Chamaeleon, dark molecular clouds and bright planetary nebula NGC 3195 can be found. Visible near the center of the above photograph is a reflection nebula surrounding a young bright star.
An Infrared Galaxy Gallery
21.03.1999
Where do stars form in galaxies? One way to find this out it to look for glowing hydrogen, a material common to hot star-forming regions. To find large areas of glowing hydrogen, the Hubble Space Telescope's NICMOS instrument surveyed about 100 nearby spiral galaxies.
M2 9: Wings of a Butterfly Nebula
20.03.1999
Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes.
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.
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