What are Comet Tails Made Of?
Explanation:
The tail of comet Hyakutake,
visible in this
recent color image,
is composed of
dust and gas driven off the
icy comet nucleus by the Sun's heat and
blown away by the solar wind.
Bathed in solar ultraviolet light,
the gas molecules break down and
are excited, producing a characteristic glow.
This glow is responsible for visible
light from the tail and
astronomers using spectroscopes can identify
the compounds involved.
The close
passage of Hyakutake presents an excellent
chance to use this technique to
explore the composition of its tail.
Typical comet
gas tail constituents are
simple combinations of hydrogen, carbon, nitrogen, and oxygen - for example,
H20 (water), CO (carbon monoxide), and CN (cyanogen) are common.
In fact, the poisonous CO and CN
compounds were seen in the spectrum of Halley's comet during
its 1910 apparition. This caused
some public concern at the time as
the Earth was expected to pass through Halley's tail!
However, stretching for millions of miles, comet tails
are extremely thin and tenuous and don't pose a danger to
the Earth's atmosphere.
Latest Comet Hyakutake images:
JPL,
Crni Vrh Observatory,
Slovenia,
Fayetteville
Observer-Times,
NASA's Night of
the Comet
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
