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ROSAT RE-ENTRY UPDATE: US Strategic Command has released an updated set of final orbital elements for ROSAT. Using these latest figures, German satellite decay expert Harro Zimmer estimates that the massive X-ray observatory re-entered Earth's atmosphere on Oct. 23rd at 01:56 UTC +/- 09. Best-fit coordinates (21.33°N, 100.32°E) suggest a re-entry over Northern Thailand.
SPACE WEATHER FORECAST FOR MARS: A bright CME blasted off the sun yesterday, Oct. 22nd, and it appears to be heading for Mars. Analysts at the Goddard Space Weather Lab expect the cloud to reach the Red Planet on Oct. 26th (forecast track). A brief discussion of what CMEs can do to Mars follows this SOHO image of the eruption:
Mars has a unique response to solar storms shaped by the planet's strange magnetic topology. Unlike Earth, which has a global magnetic field, Mars is patchily covered by dozens of "magnetic umbrellas"--remnants of an over-arching planetary field that decayed billions of years ago. When Mars gets hit by a CME, the resulting magnetic storms take place in the umbrellas. Circumstantial evidence collected by Mars Global Surveyor in the 1990s suggests that the tops of the umbrellas light up with bright ultraviolet auroras during such storms. Because the structures are distributed around the planet, these auroras can appear even at the equator.
Mars rovers and satellites should be alert for aurora equatorialis on Oct. 26th.
Bonus: Magnetic umbrellas are at the heart of one of Mars's greatest mysteries: What happened to the atmosphere? Billions of years ago, the air on Mars was thick enough to protect vast expanses of water on the planet’s surface. Now, however, the atmosphere is 100 times thinner than Earth's and the surface is bone dry. Some researchers believe that magnetic storms in the umbrellas could rip parcels of atmosphere away from Mars and propel air-filled magnetic bubbles into space. In this way, space weather could be directly responsible for the desiccation of the Red Planet.
WEEKEND METEOR SHOWER: The Orionid meteor shower peaked on Saturday, Oct. 22nd, when Earth passed through a stream of debris from Halley's comet. As many as 26 meteors per hour were visible from rural areas, according to the International Meteor Organization. Here is one of them streaking over the autumn leaves of Elverson, Pennsylvania:
"The sky was crystal clear and a moody fog was rising off the lake when I set up my camera at 1 o'clock Saturday morning," says photographer Jeff Berkes. "The Orionids we streaking bright and I counted a couple dozen during the night. I also saw 3 random meteors."
more photos: from Pete Lawrence of Selsey, West Sussex, UK; from Olivier Staiger of Crans-Montana in the Swiss Alps; from Leo Lam of Luogang, Guangzhou, China; from Jefferson Teng of Bandar Lampung, Indonesia; from Brian Emfinger of Ozark, Arkansas, USA; from Monika Landy-Gyebnar of Veszprem, Hungary; from Antti Pietikäinen of Muonio, Lapland, Finland; from Mark Staples of Waldo, Florida;
