Uranus Rock Still Unofficial 

Uranus, rings, and two moons in false-color by Hubble telescope -- Kenneth Seidelmann, U.S. Naval Observatory, and NASA

Unlike some "star naming" business, the International Astronomical Union (IAU) doesn't hand out celestial names easily. So an alleged space rock, supposedly in orbit around the planet Uranus, will not be designated the 21st moon of that gas giant planet.

The rock's saga for recognition begins in 1986 when the Voyager 2 spacecraft made several hundred images in its swing round Uranus. It took until 1999 for a University of Arizona astronomer to notice this new object on 7 of those images. With an estimated diameter of 40-km, the tiny world was given a discovery designation of "S/1986 U 10." The moon was found to be in a near urano-synchronous orbit: its 15-hour 18-minute orbital period almost corresponds to Uranus' rotation period. Astronomer William Herschel discovered Uranus in 1781 -- the first planet discovered after the invention of the telescope. (It was actually charted many times in the hundred years prior but misunderstood to be a dim star!) Confirmed moons of Uranus are given names from the works of Shakespeare and Alexander Pope. The five largest and best known moons were discovered by Earth-based telescopes: Titania and Oberon ("A Midsummer Night's Dream") were first spied by Herschel several years after discovering the planet; Ariel and Miranda ("The Tempest") were discovered almost a century apart in the mid-19th and 20th centuries; and Umbriel ("The Rape of the Lock" by Pope) was discovered at the same time as Ariel.

Alas for "S/1986 U 10," the IAU group in charge of planetary satellites wants more proof the rock actually orbits Uranus before giving it a permanent designation. This may be accomplished through Hubble Space Telescope images. This leaves Uranus with 20 confirmed moons -- third most in the Solar System -- behind Saturn with 30 and Jupiter with 28.

More Information:
Associate Press; Dec. 28, 2001; Wire Story: "Uranus Satellite Denied Moon Status"

Sweet Meteor 

Amino acids, one of the key ingredients of life, are known to exist in meteorites and have led to speculation that life or its "ingredients" was seeded on the Earth from space. Pushing this reasoning to the limit, the panspermia theory holds that complete microbes were deposited on our planet. Now, in a controversial finding, sugars have been detected in two meteorites that have already tested positive for amino acids.

"Now, you can reasonably say in meteorites there are all the ingredients of life."
-- Sandra Pizzarello, at Arizona State University

Sugars provide the carbon skeleton for many molecules as well as energy for living organisms. This tends to bolster the "life-from-space" theories. "Now, you can reasonably say in meteorites there are all the ingredients of life. We don't know how to make life, but the ingredients are there," says meteorite researcher Sandra Pizzarello, at Arizona State University.

Prior discoveries of sugars in meteorites have been made, but Earthly contamination was always a possible cause. Proponents of the seeded life theories believe the new findings prove that sugar and amino acid bearing meteorites could have been present on Earth in its early history.

But University of California at San Diego professor Jeffrey Bada pours cold water on the sugar (theory) and finds it hard to swallow. He points to the fact that meteoritic sugar compounds are not like those found in life today. He further asserts the likelihood that the first life-forms did not utilize sugars because they break down quickly.

More Information:
Associated Press; Dec. 19, 2001; Article: "Sugar Compounds Found in Meteorites"

Thanksgiving GRB

In the U.S., the day before the Thanksgiving holiday is not a day for work or unexpected surprises as the multitudes of people preparing for traditional family gatherings. But an unpredictable event on November 21, 2001 probably caused some U.S. astronomers to change their plans to join their colleges worldwide in investigating the incident.

On that day, a surprise message from 4-billion light-years away -- in the direction of the southern constellation Chamaeleon -- arrived in the form of a gamma-ray burst (GRB) that outshone the rest of the Universe in gamma-rays before rapidly fading away. Because gamma-rays don't penetrate deeply into our atmosphere, detection was made by three satellites: the Solar orbiting Ulysses, Mars Odyssey orbiting Mars, and the Italian-Dutch BeppoSAX X-ray satellite in Earth orbit were used to triangulate the position of the GRB.

GRB011121, the Thanksgiving gamma-ray burst afterglow --  M. Brown, R. Schommer, K. Olsen, B. Jannuzi, A. Dey (NOAO), A. Fruchter, J. Rhoads (STSci) AURA/NSFa

The mysterious gamma-ray bursts were first detected in the 1960s by clandestine, American military satellites. (At first it was speculated that these bursts were secret, Soviet nuclear bomb tests in space!) Research into the true nature of GRBs was hampered by their short-lived nature: millisecond to 1000-seconds is the range of duration. After the object quickly fades out of the gamma-ray spectrum it continues to glow for a much longer while -- but very dimly -- in the lower-energy spectrum that includes visible light. There has to be quick coordination between astronomical assets to pinpoint the location of the GRB and analyze it. In fact, it wasn't until 1997 that the afterglow of a GRB event was detected -- now about 30 have been spotted.

The northern edge of the constellation Chamaeleon is at a very southerly declination of -76° -- requiring a southern hemisphere telescope to look for the GRB afterglow. The day after Thanksgiving the Blanco 4-meter telescope at Cerro Tololo in Chile successfully imaged the fading visible light of the GRB. Designated GRB011121, the burst appears as a blue dot only 1% as bright as at peak. In the image here, the red dot at lower left is likely the core of the galaxy that hosted the GRB. This particular event turns out to be the closest GRB detected to date. Lucky for us that the nearer GRBs are billions of light years away: the radiation from a GRB in the vicinity of Earth would cook the Thanksgiving turkey along with all life on the planet!

Scientists estimate that GRBs are quite common: perhaps one happens in the Universe every minute. But they are still puzzled as to the nature of these dramatic events that originate in the most powerful explosions since the Big Bang. Black hole forming supernovas are one source for great outpourings of gamma-rays, but it is unknown if they are the only source. Principal investigator for the GRB detector on Ulysses, University of California at Berkeley scientist Kevin Hurley points out "that weak bursts can be close, and strong bursts can be very distant" -- indicative of beamed radiation: "If we happen to be right in the beam, the burst will look strong, regardless of its distance, " says Hurley.

GRBs may be important in understanding the creation of our Universe. Those at a distance approaching the edge of the Universe tell us about the conditions there -- the same conditions present when the Universe was much smaller at the beginning of time.

More Information:
European Space Agency; Dec. 19, 2001; Press Release: "The hunt for source of gamma-ray bursts"