Discovered on January 30 by Japanese amateur comet
hunter Yuji Hyakutake using powerful binoculars, the comet
is expected to be as bright or brighter than the stars of
the Big Dipper. The comet will make its closest approach to
Earth on March 25 at a distance of about 9.3 million miles.
It should be visible (weather and light pollution
permitting) as a dimly glowing cloud in the northern night
sky to the left of the handle of the Big Dipper, as seen
from North America.
Several NASA spacecraft, including the Hubble Space
Telescope, will attempt to take images of Comet Hyakutake.
Hubble has an especially rare and challenging task.
Astronomers say it is unlikely such a comet will ever come
this close to Earth again during Hubble's planned
operational lifetime. Since Hubble is not actively
controlled from the ground and the comet's position is not
precisely known, viewing the speeding visitor will be
especially tricky. The telescope will be preprogrammed to
point at a selected spot in the sky where the comet will be
at a specific time.
Planned Hubble science observations of Comet Hyakutake
include high-resolution imagery and ultraviolet
spectroscopy. Near the time of the comet's closest
approach, Hubble should be able to see details as small as
four miles across. Astronomers also hope to see jets of
dust emerging from the comet's nucleus.
NASA's recently launched Near Earth Asteroid Rendezvous
(NEAR) spacecraft is scheduled to take images of the comet
as a calibration exercise. Although NEAR offers a different
vantage point from Hubble, its camera was not designed to
image objects at such large distances.
Several NASA-supported ground-based observatories also
will be studying the comet during late March and in April as
the comet approaches perihelion (its closest distance from
the Sun.)
NASA's Infrared Telescope Facility (IRTF) on Mauna Kea,
HI, will dedicate several days of observing time to study
the release of dust and ice grains from the nucleus of the
comet. These ices are composed primarily of water.
Spectral observations of the molecules vaporized from the
nucleus should provide samples of molecular abundances that
were present at the time of the formation of the Solar
System. The Extreme Ultraviolet Explorer spacecraft will
make observations of neon and helium for comparison with the
water production rates to be measured by the IRTF.
Images from IRTF and many other sources will be posted
to a "virtual star party" on the Internet called the "Night
of the Comet," sponsored by NASA's Ames Research Center,
Mountain View, CA, NASA's Stratospheric Observatory For
Infrared Astronomy (SOFIA) program, and its K-12 Internet
Initiative. This home page allows anyone with access to a
computer and a modem to post and observe Hyakutake images,
track the progress of the comet, converse with NASA experts,
learn about astronomy and participate in experiments.
"Although the project is just getting started, the
initial response has been tremendous," said SOFIA project
educator Bob Hillenbrand. "Virtually every state is
covered, plus Puerto Rico, and observers are participating
from every part of the globe, including Taiwan, Australia,
Africa, Russia, South America and Europe."
"Night of the Comet" can be accessed via the Internet
at URL:
Students in California, Virginia, New York, Delaware
and Japan have begun a regular campaign of observing Comet
Hyakutake using an automated 24-inch telescope at Mount
Wilson, CA, through the NASA-supported Telescopes In
Education (TIE) project.
"We are scheduling one school or group to observe each
day of the week," said Gilbert Clark, TIE project manager
and organizer of the comet campaign. He expects the
observations to continue, weather permitting, through at
least part of April, as the comet moves from an early-
morning object in the southwest sky to an early-evening
object in the northwest sky.
Students will control the telescope and receive their
images via telephone lines at their schools, using desktop
computers and commercial software. The software package
allows them to perform digital image processing to enhance
contrast and other features, as is done with spacecraft
images. They will send their observation notes and images
to the TIE project's World Wide Web page.
A comet is a small, icy body that orbits the Sun in
an elongated orbit that can be disturbed by the on-going
orbits of the planets. Resembling a "dirty snowball," a
comet typically has a relatively tiny nucleus, often less
than six miles across. When radiation from the sun warms a
comet, ice particles from its nucleus tend to "steam"
outwards, creating a large coma or surrounding atmosphere
and a tail of material that streams away from the Sun. In
some cases, the coma and tail can be thousands or even
millions of miles across, offering dramatic viewing
opportunities. Comet Hyakutake has the potential to provide
just such a spectacle.
According to the Harvard-Smithsonian Center for
Astrophysics, Cambridge, MA, Comet Hyakutake will make the
nearest passage to Earth of any comet since 1983, and the
fifth closest this century.
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