[meteorite-list] New Comet Now Visible to Naked Eye - Comet C/2004 Q2 (Maccholz)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Dec 7 13:30:45 2004
Message-ID: <200412071818.KAA22533_at_zagami.jpl.nasa.gov>

http://www.space.com/scienceastronomy/comet_machholz_041207.html

New Comet Now Visible to Naked Eye
By Robert Roy Britt
space.com
07 December 2004

A comet discovered earlier this year has now moved close enough to be
visible without binoculars or telescopes by experienced observers under
dark skies. It is expected to put on a modest show this month and into
January.

Comet Machholz will be at its closest to Earth Jan. 5-6, 2005, when it
will be 32 million miles (51 million kilometers) away.

People with dark rural skies and a good map should be able to find it on
Moon-free nights now into January.

Backyard astronomers have been watching Machholz for months through
telescopes. It was spotted by naked-eye observers for the first time
about three weeks ago from the Southern Hemisphere, said Donald
Machholz, who discovered the frozen
chunk of rock and ice in August.

"I saw it last night for the first time with the naked eye," Machholz
told SPACE.com Friday.

Comets are made of rocky material and icy mixtures of water and various
other chemicals. As a comet approaches the Sun, the surface is heated
and essentially boils off. Scientists call the process sublimation. The
gas and dust creates a head, also called a coma, and sometimes a tail.
Sunlight reflects off the material, making some comets visible from Earth.

Comet Machholz, officially named c/2004 Q2, is not expected to produce
the sort of spectacular display put on by comet Hale-Bopp in 1997 or the
periodically stunning Halley's comet.

Astronomers cannot say exactly how bright Machholz will get, because it
is notoriously difficult to predict the behavior of comets making their
first observed close trip around the Sun. Scientists don't fully
understand the composition of comets, nor their variety, so they don't
know how much stuff will sublimate nor how fast.

Machholz is expected to reach magnitude 4.0, based on an early estimate.
On this astronomers' scale, smaller numbers represent brighter objects.
The dimmest things visible under perfectly dark skies are around
magnitude 6.5. The brightest star, Sirius, is magnitude minus 1.42.

Recent observations suggest Machholz will do at least as well as first
predicted.

"The comet is doing better than expected and is about 0.5 magnitudes
brighter than expected," Machholz said. "So it will probably get
brighter than the Andromeda Galaxy, brighter than magnitude 4.0."

The Andromeda Galaxy is the furthest object visible to the unaided human
eye under dark skies. It is a magnitude 3.4 object.

If the comet were to become roughly magnitude 3.0, it would still appear
common among the sea of stars available to dark-sky observers. City and
suburban dwellers would likely not find it without optical aid. In
either case, binoculars or a small telescope might reveal the comet as
more of a fuzzy patch, and if it develops a significant tail, that could
be visible too.

Machholz, who has found nine other comets, suggests looking for his
latest discovery when the Moon is out of the picture, such as around
Dec. 11 when it will be at its New phase.

"The comet can still be seen when the Moon is out, but it will be
difficult," he said by email. "Use binoculars or a wide-field (low
power) telescope, and/or get to a dark site."

The comet is low on the horizon now, where the atmosphere makes for poor
viewing. By early January, the comet will be much higher in the sky,
improving viewing conditions.
Received on Tue 07 Dec 2004 01:18:22 PM PST


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