Rosetta is
deciphering
comet’s tale
By Dr. Sten Odenwald
Comet 67P/Churyumov-Gerasimenko
(I’ll call it Comet 67P) has been minding
its own business for billions of years
as it quietly looped around the Sun
every 6.5 years. Discovered in 1969 by
astronomers Klim Ivanovych Churyumov
and Svetlana Ivanovna Gerasimenko,
it spins around on its own axis every 12
hours and is about 2 miles across. Even
with a mass of 10 billion tons, it is still small
compared with the giants of its class,
like Hale-Bopp, at 40 miles across!
So far, spacecraft have visited Halley’s,
Tempel-1, Hartley-2, Wild-2 and Borrelly,
so Comet 67P joins a very select group
of “dirty icebergs” gliding through space
in orbits favorable for human scrutiny.
Despite their brilliance in the night sky,
their hard nuclei are as dark as aspault,
reflecting less than 5 percent of the
sunlight that falls on their surfaces. Far from
featureless ice balls, they show amazing
surface detail that in most cases has
been studied at high resolution. Take a
look at this recent image of Comet 67P
taken by the European Space Agency’s
Rosetta spacecraft just last month.
This beautiful view shows off a wide
range of the comet’s features: from the
jets emanating from the ‘neck’ region, to
the steep cliffs towering over both smooth
and grooved terrain,