In 1995, Comet 73P/Schwassmann-Wachmann 3 (hereafter, "73P") did
something unexpected: it fell apart. Astronomers watched with interest
as the comet's nucleus, for no apparent reason, split into at least five
"mini-comets" flying single file through space. The disruption produced
a cloud of dust and gas almost visible to the naked eye from Earth, one
hundred and fifty million miles away.

We're about to get a much closer look. In May 2006 the fragments are
going to fly past Earth closer than any comet has come in almost eighty
years.

"This is a rare opportunity to watch a comet in its death throes---from
very close range," says Don Yeomans, head of NASA's Near Earth Object
Program at JPL.

There's no danger of a collision. "Goodness, no," says Yeomans. "The
closest fragment will be about five million miles away." That's twenty
times farther than the Moon\--close enough for a great view without
being scary.

"The Hubble Space Telescope will be watching," continues Yeomans. "Also,
the giant Arecibo radar in Puerto Rico will 'ping' the fragments to
determine their shape and spin." Even backyard astronomers will be able
to photograph the mini-comets as they file through the constellations
Cygnus and Pegasus: sky map.

How bright will they be? Ironically, these very close comets will not be
very bright. The larger fragments are expected to glow like 3^rd^ or
4^th^ magnitude stars, only dimly visible to the unaided eye.

"Remember," says Yeomans, "these are *mini*-comets." They're small, not
like the Great Comets of 1996 and 1997, Hale-Bopp and Hayutake, which
could be seen even from light-polluted cities. To see the fragments of
73P you'll need to go to the countryside---and don't forget your
binoculars.

The best times to look are May 12^th^ and 13^th^. Those are the dates of
closest approach for fragments B and C, the biggest of the pieces first
seen eleven years ago. Amateur astronomers have already spotted the two
approaching Earth, as shown in this photo from XXX:

In 1995, astronomers labeled the original five fragments A -- E.
Fragment A has since dissolved while new fragments G and H have been
discovered. As the comet approaches, even more fragments may come to
light. No one knows exactly how long the "string of pearls" is.
Discovery awaits.

Bonus: There might be a meteor shower.

This is very uncertain, indeed, forecasters consider it unlikely. But an
expanding cloud of dust from the breakup of the comet could brush past
Earth in May producing a display of meteors.

Meteor expert Paul Wiegert of the University of Western Ontario has
studied the possibility:

"We believe the cloud of debris is expanding too slowly to reach Earth
only 11 years after the break-up," he says, "but it all depends on what
caused the break-up---and that we don't know."

"It may be thermal stress, with the icy nucleus cracking like an ice
cube dropped into hot soup: the comet broke apart as it approached the
Sun after a long sojourn the frigid outer solar system," he explains.
"If this is what happened, then the debris cloud should be expanding
slowly, and there will be no strong meteor shower."

On the other hand, what if "the comet was shattered by a hit from a
small interplanetary boulder?" A violent collision would produce
faster-moving debris that could reach Earth in 2006.

Weigert expects to see nothing, but he encourages sky watchers to be
alert. It wouldn't be the first time a dying comet produced a meteor
shower:

"One outstanding example is comet Biela, which was seen to split in
1846, and had completely broken apart by 1872," he says. "At least three
very intense meteor showers (3000-15000 meteors per hour) were produced
by this dying comet in 1872, 1885 and 1892."

Weigert and colleagues have calculated the trajectory of 73P's dust
cloud, assuming a thermal breakup. Their results: dust should reach
Earth in 2022, "producing a minor meteor shower\--nothing spectacular.
However," he adds, "the ongoing splitting of the comet means new
meteoroids are being sent in new directions, so a future strong meteor
shower from 73P remains a real possibility."

The watch begins on May 12^th^.

"The pieces have been orbiting the sun ever since and now they're about
to pass by Earth."

On May 13^th^, fragment

On May 13 and 14, pieces of the comet will fly by Earth, one by one,
only 5 to 7 million miles away.

What's interesting about this encounter is not how close it is---it *is*
close---and not

The "swarm" consists

Actually, it's a swarm of comets. On May 13, 2006, three to five pieces
of Comet 73P/SW3 will approach Earth

One May 13, 2006, fragments of comet

Date: May 13, 2006.

Comet: 73p/SW-3

Distance: less than 30 million miles, or

Lord; this is quite rare; there will be an attempt to observe it with
Hubble, Arecibo, Goldstone, quite nice radar map, they don't have the
clean signal that asteroids do, cloud of debris puzzles, only a couple
off successful comet bounces, there is no radar shape model available
for any comet; we'll be lucky if we get a rough shape, actually, coming
that close in terms of near-Earth objects, it's how rapidly its
spinning, how much ; optically you can't see the nucleus; when it gets
close enough to be resolved, it throws up a cloud of gas and dust;

Knowing the distance and magnitude 4%

They fragment for no particular reason frequently, a couple of dozen
cases when this has happened close look at a fragmented comet; there
will be an extensive ground-based campaign to observe it ; it's always
interesting to observe these comets are very fragile; when SL-9 collided
with Jupiter small comet; 40 to 60 km across; C,B,G IAU Circ 8679: Roy
Tucker Tucson AZ, Mt. Lemmon; G B;

Nice opportunity to observe in its death thoughs;

C June 6.95

B June 7.94

G June 8.1