Astronomy

"Have they not looked at the sky above. We structured it and made it beautiful and how there are no fissures in it? " <Qur'an-Qaf 50:6>

Jan 2002 - According to CNN, Scientists at NASA's Jet Propulsion Laboratory are monitoring two asteroids that are passing relatively close to Earth on Wednesday. At its closest point, asteroid 2002 AO11 will come within 3 million miles of Earth. Further away, asteroid 1991VK will miss our planet by almost 7 million miles. While such distances may seem large, these asteroids are actually passing quite nearby, considering the size of the solar system.

But neither of these asteroids poses a threat to Earth, NASA said. Asteroid disaster movies have been popular with Hollywood in recent years, with such films as "Deep Impact" and "Armageddon" dramatizing the global devastation that would certainly occur if a sizable asteroid hit earth. Such giants have hit the planet. Scientists speculate that one such monster did so much damage when it struck about 65 million years ago that it brought an end to the age of dinosaurs. And scientists say such an event, while unlikely, could happen again with little warning. Researchers do not know how many so-called Near Earth Objects (NEOs) are out there. They have identified about 600 nearby and are continuing to watch for other large asteroids. Near misses are not uncommon. Only days ago, on January 7, the asteroid 2001 YB5 passed just 510,000 miles from Earth, less than twice the distance between the moon and Earth. Astronomers first spotted it in December 2001.

Dec 2001 - The black hole and the star that revolves around it and feeds it are in the stellar system called GRS1915+105. Black holes suck in everything near them including light and can only be detected by the activity around their edges. Stellar black holes, the remnants of dead sun-like stars, typically have the mass of three to seven suns. "The one that I found is 14," Jochen Greiner, of the Astrophysical Institute, said in a telephone interview. Greiner and his colleagues identified the star that feeds the black hole by studying the steady flow of stellar material. In research reported in the science journal Nature, they estimated the mass of the black hole by analyzing the orbital motion of the star around it.
The distance between the star and the black hole is about half the distance between the Earth and the Sun. The size of GRS1915+105, which astronomers have dubbed a micro quasar, has cast doubt over the theories on how black holes are formed. Scientists consider micro quasars, binary systems consisting of a normal star and a black hole or neutron star, as natural laboratories for testing Einstein's general theory of relativity. GRS1915+105 is one of a handful of micro quasars in our galaxy. Scientists are puzzled by the size of the black hole because the interaction in a binary system increases the mass loss of the star and they don't know how it can retain enough mass to form such a massive black hole.

"The big mystery now is how can theory explain these 14 solar masses which I have measured," said Greiner.
"The present theory cannot explain how to produce such large masses," he added.
source:www.wired.com

Oct 2001 - Situated in the constellation Coma Berenices (Berenice's Hair) is an appropriately shaped constellation. NGC 4314 looks like a fiery crown. But it is really one of the most exotic galaxies that humans have catalogued..
While the Hubble picture here looks like an entire galaxy, it is really only the central part of a much larger galaxy. This “crown” is what astronomers call a “nuclear ring.” Each "gem" in the crown is a cluster of stars -- thousands of stars that are huddling together, burning so hot that they set the clouds of hydrogen that surround them aglow. Each star cluster is swaddled in a hydrogen blanket -- the raw material out of which it formed. When the scorching radiation hits this gas it causes the electron in each hydrogen atom to dance, as in a fluorescent light, producing the purple glow seen around the youngest and hottest of these clusters.

This Hubble image revealed that each of these purple clusters is a conglomeration of stellar infants -- each is just a few million years old. In contrast, most of the other stars in this galaxy are billions of years old -- thousands of times older than the babies in the clusters.

Without a supreme court to overturn it, the law of gravity is what keeps the differently colored stars segregated in NGC 4314. If you think of each cluster of stars as a stellar neighborhood, then gravity is coming along like a wrecking ball to tear down the newly built neighborhoods before they even get established. The tidal forces generated by the combined gravity of the other stars and gas in the galaxy conspire to rip apart the clusters of stars after a few million years. We know this because we can see the detritus of ruined neighborhoods as the diffuse blue patches, which look like spiral "arms." The stars in these regions are hundreds of millions of years old. Their neighborhoods demolished, they are cast out, away from the beltway of new construction, condemned to wander the galaxy alone.

Gravity is a cruel galactic city planner, but it has engineered quite a beautiful crown of stars for Berenice's hair.

Oct 2001 - The NEAR-Shoemaker spacecraft was designed to provide a comprehensive characterization of the S-type asteroid 433 Eros, an irregularly shaped body with approximate dimensions of 34 X 13 X 13 km. Following the completion of its year-long investigation, the mission was terminated with a controlled descent to its surface, in order to provide extremely high resolution images. The landing area is marked by a paucity of small craters and an abundance of 'ejecta blocks'. The last sequence of images reveals a transition from the blocky surface to a smooth area, which we interpret as a 'pond'. The closest image, from an altitude of 129 m, shows the interior of a 100-m-diameter crater at 1-cm resolution.