Encore Portrait of Stars Near and Far

SOHO, a space-based solar observatory that has helped revolutionize our understanding of the sun, began tumbling wildly in June, the victim of errant commands by ground controllers. It took engineers several months to rescue the spacecraft. Despite their efforts, some of SOHO's instruments were damaged by the months without full power.

Though SOHO was back in place and up to full power by September, two of three gyroscopes used to orient the satellite now appear to be beyond repair, possibly limiting SOHO's useful lifetime. The image of the sun shown below was taken on June 24, just a few hours before the probe lost contact with ground control.

THESE SOHO images show the aftereffects of a flare erupting above the sun's surface. The shock wave created by the flare ripples across the surface like seismic waves from an earthquake--but this one contained 40,000 times the energy of the San Francisco earthquake of 1906. Much as geologists use seismic data to plumb Earth's depths, astronomers will use these data to better understand the sun's interior.

A RING OF bright, newly formed stars around the core of galaxy NGC 4314 was captured in a Hubble Space Telescope image released in June. The ring seems to be the only area in the galaxy where stars are being born.

THIS BLOB in the nearby Small Magellanic Cloud is a nursery for very large, very bright stars. By studying these suns, astronomers will better understand similar stars in distant galaxies.

RELATED ARTICLE:

THE SECOND BIGGEST BANG. Gamma-ray bursts--spasms of high-energy radiation--have puzzled astronomers for years. In May, astronomers reported conclusive evidence that the bursts come from distant corners of the universe, not from near our own galaxy as some had argued. Thus, each burst must be unimaginably powerful. In fact, astronomers claim that the only event to surpass the energy of a gamma-ray burst was the Big Bang itself. What actually causes the bursts is still a mystery, but catastrophes such as the collision of a neutron star and a black hole have been proposed.

OUR WET MOON. The Lunar Prospecto, which reached the moon last January. detected evidence of 6 billion tons of ice near the lunar poles--enough to cover New Jersey with a foot of water. The craft also detected signs that the moon has a solid iron core 300 to 500 mites in diameter.

THERE GOES THE NEIGHBORHOOD. A refined estimate in March puts the sun a mere 23,000 light-years from the center of our galaxy, 5,000 light years closer than astronomers had thought.

THE UNIVERSE is older and lighter than previously estimated, several teams of astronomers reported last January. Through studies of distant supernovas and galactic dusters, the age of the universe was calculated to be about 15 billion years, old enough to account for the age of the oldest stars. These studies also suggest that there is much less mass in the universe than is needed for gravity to halt its expansion.

TWO NEWLY DISCOVERED moons of Uranus have been named Caliban and Sycorax, after the characters in Shakespeare's Tempest.

AN INTENSE PULSE of radiation bombarded Earth's atmosphere in August. The gamma rays and X-rays came from a star 20,000 light-years away--SGR1900+14, a member of a newly discovered class of stars called magnetars, which are thought to be rapidly spinning neutron stars with enormous magnetic fields. The radiation pulse temporarily knocked out two satellites.

ALTHOUGH ITS PRIMARY mission ended in 1997, the Galileo probe continues to send back data about Jupiter and its moons. Among the findings: evidence of an ocean on Callisto: salty deposits on Europa, probably also from a subsurface ocean; and a close look at storms raging at the Great Red Spot.

THE MOST DISTANT galaxies in the universe were detected in October. Light from the oldest of them dates back to when the universe was only about 750 million years old.

SEVERAL MORE PLANETS were discovered around distant stars. One has an orbit similar to Earth's, though the planet itself is probably larger than Jupiter. A new instrument--a spectrometer-interferometer hybrid--was demonstrated in June. It may be sensitive enough to detect a planet as small as Earth around another star.

COPYRIGHT 1999 Discover
COPYRIGHT 2000 Gale Group