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METEOR SHOWER: The Southern Delta Aquarid meteor shower peaks on July 28th. Go outside before dawn on Friday, look south, and you could see a meteor every five minutes: sky map. No one knows where the Delta Aquarids come from. A dead comet? A shattered asteroid? Each streak of light is a mystery.
BEWARE THE MARS HOAX: Just when you thought it was safe to read your email, a new Mars Hoax is spreading. The widely-circulated message tells us "the Red Planet is about to be spectacular. On August 27th, Mars ... will look as large as the full Moon." Not. (continued below)
Here are the facts: On August 27, 2006, Mars will be on the other side of the solar system, 385 million km from Earth and very dim. So forget about Mars. If you want to see something truly astronomical on August 27th, look east before dawn for a pretty conjunction of Venus and Saturn: sky map.
WHAT'S ON TOP? On July 22nd, "my wife kindly blocked out the sun," says photographer Charlie Szabototh of Wiarton, Ontario, "revealing a beautiful sun halo criss-crossed by contrails." The question is, what's on top? The halo or the contrails? Look carefully at the image, then scroll down for the answer:
The contrails are on top. See the dark fringes to the left of the contrails? Those are contrail shadows, cast down on the icy cloud layer that makes the sun halo. "I always find contrail shadows counter-intuitive," notes atmospheric optics expert Les Cowley. "Somehow we expect objects we see in the air to be in front of the clouds. These bright contrails, however, are not beneath the clouds; they are above them as their shadows reveal."
more images: from Riccardo Di Nasso of Pisa, Italy; from Laurent Laveder of Bretagne, France; from Martin Mc Kenna of Northern Ireland; from Rodrigo Roesch of Zion, Illinois.