Scientists Tailing Comet
Celestial Object First Seen in N.M.
10/25/95

John Fleck
Journal Staff Writer

NASA's Hubble Space Telescope pointed its lens at comet Hale-Bopp Monday and Tuesday, as astronomers began an observation campaign of the New Mexico-discovered comet.
After initial fears that the bright comet was undergoing an outburst when it was discovered in July and would fade, scientists now believe Hale-Bopp is big and bright enough to offer a bonanza of new scientific data -- and possibly a notable public show.
Now located beyond the orbit of Jupiter, Hale-Bopp is headed toward the sun in an orbit that will bring it to within less than 100 million miles of Earth -- close in astronomical terms -- when it is at its brightest in the spring of 1997.
"I think it's going to be the brightest comet in many, many years," said Yoji Kondo, chief scientist for NASA's International Ultraviolet Explorer satellite, which figures prominently in the Hale-Bopp observation plans.
Kondo's satellite already has detected unusual characteristics in the cloud of dust surrounding Hale-Bopp, which astronomers are now trying to sort out, said Michael A'Hearn, a professor at the University of Maryland and one of the nation's leading comet experts.
Cloudcroft astronomer Alan Hale was the first scientist to see the comet, using a telescope in the driveway of his mountain home in July. Amateur stargazer Thomas Bopp, out in the desert of southern Arizona, spotted the comet later that same night, and the two are credited as co-discoverers.
Hale said in a telephone interview Tuesday that he has been looking at the comet every few nights as it hangs in the constellation Sagittarius, visible now only with a telescope.
The comet will be obscured by a full moon in early November, then will be visible low in the southern sky until late November, when it will disappear below the horizon.
It will reappear early next year as it moves closer to the sun, and by the spring of 1997, scientists expect it to be one of the most impressive comets in recent memory -- a "jumbo comet," according to Kondo.
A'Hearn is working with Kondo to do a series of observations using the International Ultraviolet Explorer, a satellite launched by NASA in 1978 that is known in the science community as something of a workhorse.
Comets are icy, rocky objects that lurk in the solar system, usually out of sight because of their small size and great distance from the sun and Earth.
Occasionally one is pulled in by the gravity of the planets or sun, sweeping through the inner solar system and brightening as the sun burns away at it, creating a cloud of dust and ice that can become visible.
Comets are not uncommon, but Hale-Bopp has drawn special attention because it is so bright so early in its journey toward the sun.
A'Hearn hopes to take a series of observations with the satellite as Hale-Bopp approaches the sun, to study the evolution of the comet's emissions over time.
When it gets close to the sun, its size and brightness should help scientists better understand its chemical composition, A'Hearn said.