Astronomy Picture of the Day
Discover the cosmos! Each day we feature a different image or photograph
of our fascinating universe, along with a brief explanation written by a
November 12, 1995
Blue Jet Lightning
Credit: D. Sentman, G. Wescott,
U. Alaska Fairbanks,
Recently two new types of lightning have
been verified: red sprites and
jets. These atmospheric discharges occur very high in the
Earth's atmosphere - much higher than the
familiar form of
appear blue in color and go from the tops of clouds to a height of about 50
kilometers. Because blue jets typically last almost a full second,
one can easily see the jet rise from the clouds with a fast video camera.
Blue jets appear as narrow cones and travel about 100
kilometers per second. The existence of blue jets
had been suggested and recorded by Shuttle astronauts
in the 1980s.
In 1994 aircraft were flown above
massive thunderstorms with high speed video equipment that
verified and better documented these
spectacular events. The above black & white picture shows
several blue jets rising from a thunderstorm simultaneously. Part of the
aircraft is visible in silhouette on the right. Scientists are unsure of
the cause and nature of blue jets.
Tomorrow's picture: Virgo Cluster Galaxies
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