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AURORA OUTLOOK: There is a slim chance that a solar wind stream will buffet Earth's magnetic field on May 20th and spark a mild geomagnetic storm. High-latitude sky watchers should be alert for auroras around that date.

BIG SUNSPOT: Big sunspot 609 split in two this weekend. Each half is about three times as wide as Earth. The active region remains easy to see--but never stare at the sun. Look for it using safe solar observing techniques.

Above: A 5-day animation of SOHO images, spanning May 12th-17th, shows the rapid growth of sunspot 609 and its weekend split.

ANATOMY OF A COMET: Comet tails are made of two substances, gas and dust, which drift in different directions. The dust lingers behind the comet and traces its orbit. The gas is pushed by the solar wind into a straight line pointing away from the sun. Comets, therefore, have two tails, the dust tail and the gas tail (the gas tail is also known as the "ion tail"). Both were captured in this May 14th photo of Comet NEAT (C/2001 Q4) by David Harvey of the Kitt Peak National Observatory in Tucson, Arizona:

Would you like to see Comet NEAT? You can. Step outside about an hour after sunset and look southwest. The comet is that faint fuzzball gliding through the constellation Cancer. City dwellers will need binoculars to see it, but rural observers can spot the comet with their unaided eyes. [sky maps: May 17, May 18]

more images: from Rick Schrantz on a suburban patio near Lexington, KY (May 16); from Steffen Brueckner of Stuttgart, Germany (May 16); from Bob Yen at Hungry Valley, CA (May 11-16); from Mark Hanson at the Yanna Research Station in Wisconsin (May 16); from Thorsten Eschweiler of Geilenkirchen, Germany (May 14); from Giovanni Sostero at Mount Zoncolan, Italy (May 17); from Soffiantini Andrea of Carezza, Trentino, Italy (May 16); from John Pane of Marshall Township, Pennsylvania (May 16).

THE ISS & JUPITER: The International Space Station (ISS) eclipsed Jupiter on May 13th. The eclipse wasn't easy to observe because the path of totality was only 80-meters wide, but Gary Trapuzzano of Pennsylvania managed to do it. Pictured right is his video recording of the event.

"At the last minute my friend Mike Atwell and I decided to try to capture the eclipse on video," says Trapuzzano. "After driving to the site and setting up, we had only 38 seconds to spare. Because I didn't know how close the ISS would get to Jupiter, I exposed the image to include Jupiter's moons. Had I known our location would be almost exactly on the centerline, I would have reduced the exposure to show more detail. All-in-all, doing this was a total blast for both of us."