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Astronomy Picture Of the Day (APOD)
Mercury in Stereo: Craters Within Craters
11.01.1997
This Stereo image pair of craters on on Mercury was produced using data from NASA's robot explorer Mariner 10 which performed three close flybys of the Sun's closest companion, two in 1974 and one in 1975. However, the spacecraft was not equipped with a Stereo camera!
Titania's Trenches
10.01.1997
British astronomer Sir William Herschel discovered Titania and Oberon in 1787, 210 years ago today. He wasn't reading Shakespeare's A Midsummer Night's Dream though, he was making the first telescopic observations of moons of the planet Uranus (a planet which he himself discovered in 1781).
Eclipsed Moon in Infrared
9.01.1997
Last September's total lunar eclipse disappointed many observers in the Eastern and Midwestern US who were cursed with cloudy skies. However, the Midcourse Space Experiment (MSX) satellite had a spectacular view from Earth orbit and SPIRIT III, an onboard imaging infrared telescope, was used to repeatedly image the moon during the eclipse.
Hazing Jupiter
8.01.1997
A dramatic mosaic of recent images from the Galileo spacecraft reveals details of swirling clouds and a thick stratospheric haze in the atmosphere of Jupiter, the Solar System's largest planet. This false color...
Grey Sun Seething
7.01.1997
The Sun's surface is not smooth. It has thousands of bumps called granules and usually a few dark depressions called sunspots. Each of the numerous granules is the size of an Earth continent, but much shorter lived.
Red Sun Streaming
6.01.1997
The Sun is leaking. In fact, it is gushing: particles stream away from the Sun at hundreds of kilometers per second. Some of these particles strike the Earth and cause aurora. Most particles, however, either surround the Sun as a huge solar corona or glide into interstellar space as the solar wind.
Blue Sun Glaring
5.01.1997
The Sun is a bubbling ball of extremely hot gas. In this false-color picture, light blue regions are extremely hot - over 1 million degrees, while dark blue regions are slightly cooler. The camera filter used was highly sensitive to the emission of highly charged iron ions, which trace the magnetic field of the Sun.
Too Close to a Black Hole
4.01.1997
What would you see if you went right up to a black hole? Above are two computer generated pictures highlighting how strange things would look. On the left is a normal star field containing the constellation Orion. Notice the three stars of nearly equal brightness that make up Orion's Belt.
A Star Where Photons Orbit
3.01.1997
The above computer animated picture depicts how a very compact star would look to a nearby observer. The star pictured is actually more compact that any known except a black hole, so it is only hypothetical. The observer is situated at the photon sphere, where photons can orbit in a circle.
A Wolf-Rayet Star Blows Bubbles
2.01.1997
Wolf-Rayet stars can blow bubbles. These unusual stars are much hotter and more luminous than our Sun. All extremely massive stars will eventually evolve though a Wolf-Rayet phase. Approximately 200 Wolf-Rayet stars are known in our Milky Way Galaxy. Wolf-Rayet stars generate bubbles because they continually eject their outer atmosphere as a stellar wind.
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