Comet making closest approach ever of Earth, finally becoming visible in Northern Hemisphere
Marcia Dunn, The Associated Press
Tue, 5 Mar 2013 14:01:00 CST
CAPE CANAVERAL, Fla. - A recently discovered comet is closer than
it's ever been to Earth, and stargazers in the Northern Hemisphere
finally get to see it.
Called Pan-STARRS, the comet passed within
100 million miles (160 million kilometres) of Earth on Tuesday, its
closest approach in its first-ever cruise through the inner solar
system. The ice ball will get even nearer the sun this weekend — just 28
million miles (45 million kilometres) from the sun and within the orbit
of Mercury.
The comet has been visible for weeks from the Southern Hemisphere. Now the top half of the world gets a glimpse as well.
The
best viewing days should be next Tuesday and Wednesday, when Pan-STARRS
appears next to a crescent moon at dusk in the western sky. Until then,
glare from the sun will obscure the comet.
California astronomer
Tony Phillips said the comet's proximity to the moon will make it easier
for novice sky watchers to find it. Binoculars likely will be needed
for the best viewing, he said, warning onlookers to avoid pointing them
at the setting sun.
"Wait until the sun is fully below the horizon
to scan for the comet in the darkening twilight," Phillips advised in
an email sent from his home and observatory in the Sierra Nevada
mountains.
Pan-STARRS' name is actually an acronym for the
Hawaiian telescope used to spot it two years ago: the Panoramic Survey
Telescope and Rapid Response System. The volcano-top telescope is on
constant prowl for dangerous asteroids and comets that might be headed
our way.
Thought to be billions of years old, the comet originated
in the distant Oort cloud — a cloud of icy bodies well beyond the
orbits of Neptune and Pluto — and somehow got propelled toward the inner
solar system.
It's never passed by Earth before, Phillips said.
A much brighter comet show, meanwhile, is on the way.
Comet
ISON may come close to outshining the moon in November. It was
discovered last September by Russian astronomers and got its acronym
name from the International Scientific Optical Network.
Neither Pan-STARRS nor ISON pose a threat to Earth, according to scientists.
