SOHO Sungrazer
SOHO,
the space-based SOlar and Heliospheric Observatory,
has become by far the
reigning
champion facility for discovering comets,
its total having recently reached
200.
As might be expected of a solar observatory,
most of the
SOHO discovered
comets are sungrazers, destined
to dive within a mere 50 thousand kilometers or so
of the solar photosphere.
At that range the intense heat and gravitational forces make it
unlikely these primitive chunks of ice and dust
will survive.
Based on their similar orbits, as first
worked
out by
19th
century German astronomer Heinrich Kreutz,
all
sungrazers are
believed to originate from a single large parent comet which
broke up during a
perihelion passage perhaps 2,000 years ago.
Over time, pieces have continued to split off producing a family
of smaller comets which seem to travel in the same orbit.
These
frames
from SOHO's coronograph were taken two hours
apart on April 29 of this year.
They show a sungrazer (SOHO comet discovery
number 111) with a
long, bright tail headed toward its fiery encounter.
The sun itself is hidden behind the coronograph's occulting disk
at each frame's upper right.