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Astronomy Picture Of the Day (APOD)
APOD Turns Eight
16.06.2003
The first APOD appeared eight years ago today, on 1995 June 16. To date, we estimate that APOD has now served over 100 million space-related images. We again thank our readers and NASA...
Noctilucent Clouds
15.06.2003
Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above.
The Planetary Nebula Show
14.06.2003
What do the Owl, the Cat's Eye, the Ghost of Jupiter, and Saturn have in common? They're all planetary nebulae of course, glowing gaseous shrouds shed by dying sun-like stars as they run out of nuclear fuel.
Neptune: Still Springtime After All These Years
13.06.2003
In the 1960s spring came to the southern hemisphere of Neptune, the Solar System's outermost gas giant planet. Of course, since Neptune orbits the Sun once every 165 earth-years, it's still spring for southern Neptune, where each season lasts over four decades.
Cyg X-1: Can Black Holes Form in the Dark
12.06.2003
The formation of a black hole from the collapsing core of a massive star is thought to be heralded by a spectacular supernova explosion. Such an extremely energetic collapse is also a leading explanation for the mysterious cosmic gamma-ray bursts.
Two Million Galaxies
11.06.2003
Our universe is filled with galaxies. Galaxies -- huge conglomerations of stars, gas, dust -- and mysterious dark matter are the basic building blocks of the large-scale universe. Although distant galaxies move away from each other...
Zooming in on the First Stars
10.06.2003
What became of the first stars? No known stars appear to be composed of truly primordial gas -- all of the stars around us have too many heavy elements. Our own Sun is thought to be a third generation star, with many second-generation stars seen in globular clusters.
APOD: 2003 June 9 Ш The Pencil Nebula Supernova Shockwave
9.06.2003
At 500,000 kilometers per hour, a supernova shockwave plows through interstellar space. This shockwave is known as the Pencil Nebula, or NGC 2736, and is part of the Vela supernova remnant, an expanding shell of a star that exploded about 11,000 years ago.
Rhea: Saturn's Second Largest Moon
8.06.2003
Rhea is the second largest moon of Saturn, behind Titan, and the largest without an atmosphere. It is composed mostly of water ice, but has a small rocky core. Rhea's rotation and orbit are locked together (just like Earth's Moon) so that one side always faces Saturn.
Warped Spiral Galaxy ESO 510 13
7.06.2003
How did spiral galaxy ESO 510-13 get bent out of shape? The disks of many spirals are thin and flat, but not solid. Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center.
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