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 professional astronomer.

November 12, 1995

Blue Jet Lightning
Credit: D. Sentman, G. Wescott, Geophysical Institute, U. Alaska Fairbanks, NASA

Explanation: Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning. Blue jets 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 has been suggested previously, but only in 1994 were aircraft flown above massive thunderstorms with the high speed video equipment necessary to verify 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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Authors & editors: Robert Nemiroff (GMU) & Jerry Bonnell (USRA).
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