Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2001 November 22
Explanation: Returning from orbit, space shuttles enter the atmosphere at about 8 kilometres per second as friction heats their protective ceramic tiles to over 1,400 degrees Celsius. By contrast, the bits of comet dust which became the Leonid meteors seen on November 18, were moving at 70 kilometres per second, completely vapourizing at altitudes of around 100 kilometres. In this single 5 minute time exposure, three Leonid meteors are shooting through skies above Spruce Knob, West Virginia, USA. Background stars are near the constellation Orion. The brightest meteor, a fireball, dramatically changes colours along its path and leaves a smokey persistant trail drifting in high-altitude winds. From that extremely dark site, at an elevation of 1,200 metres, astrophotographer Jerry Lodriguss reports, "We observed a [zenithal hourly rate] of about 3,600 at 10:30 UT and very high rates from 9:30 UT until well into the start of astronomical twilight at 10:50 UT. It was quite a spectacular storm, with bolides going off like flashbulbs, green and red fireballs and other fainter Leonids in all parts of the sky."
Authors & editors:
Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.