Where's Saturn? Is that a UFO--or the ISS? What's the name of that star? Get the answers from mySKY--a fun new astronomy helper from Meade. ASTEROID FLYBY: Asteroid 2007 TU24 is approaching Earth and NASA radars have measured its size and shape: 250 meters wide and lopsided. There's no danger of a collision, but on Jan. 29th the space rock will be close enough (1.4 lunar distances) to photograph through backyard telescopes as it speeds through the constellation Cassiopeia glowing like a 10th magnitude star. [ephemeris] [3D orbit] [radar image] KERN ARC: To the casual observer, this photo of ice halos around the sun taken by Marko Mikkilä of Finland may not seem extraordinary, but to experts it is "the halo photo of the decade." The excitement springs from a faint circle around the zenith labeled "Kern arc": The rare Kern arc completes the circle of the much brighter and frequently seen circumzenithal arc. "Kern arc sightings are few indeed, only two or three reports in the last century, and it has never ever been photographed--until Mikkilä did it last Nov. 17th," says atmospheric optics expert Les Cowley. "As a diamond dust swarm generated the halo, Mikkilä took dozens of images. The picture above is a stack of 16 images. Astronomers use stacking to reveal faint or elusive details and it does the same for halo displays. However, Mikkilä’s Kern arc was so clear that it is visible on individual images." "Why is the Kern arc so very rare? The arc has a ray path like that of the circumzenithal arc but with a crucial extra reflection inside flat plate crystals. The contorted path is not possible inside ordinary regular hexagonal plates, instead they have to be almost triangular. Mikkilä sampled and photographed under a microscope the crystals falling around him and lo, many had the required triangular shape." "The next time you see a bright grin in the sky, look around for the complete circle," urges Cowley. "You might catch a Kern arc of your own." NEW: Spaceweather.com has a new tool for reader discussion. Click on this symbol to add your comments to a story. LIGHT POLLUTION FROM 24,000 FT: On Jan. 15th, Rick Stankiewicz looked out the window from his seat aboard a night flight from Toronto to Thunder Bay, Ontario. "I expected to see a blank slate of clouds," he says. "Instead I noticed orange glowing patches." "It was all too obvious what I was observing," continues Stankiewicz. "These glowing cloud patches were indicators of light pollution from communities across southwestern Ontario. This misdirected and wasted light was filtering through the cloud deck to my airplane window at 24,000 ft. I was amazed at their number; within minutes, I counted dozens of glowing patches. I used my digital camera (a Canon 400D) to capture as best as I could what I saw. There is no denying it; societies beacons of light are also signposts of wasted energy and resources." |