| 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. |
MERCURY FLYBY: Last week's historic flyby of Mercury by NASA's MESSENGER spacecraft gathered 500 megabytes of data and more than a thousand high-resolution photos covering nearly six million square miles of previously unseen terrain. "Discoveries are at hand," say members of the mission science team. Click here for a hint of things to come.
NACREOUS CLOUDS: People across Scandinavia are still talking about a stunning display of nacreous clouds that rolled over the Arctic Circle on Jan. 19th and 20th. "I have never seen such huge, colourful, mutating clouds," says Kalinka Irina Martín Iglesias who sends this picture from Tunhovdfjorden, Norway:
The display was so bright, she actually used sunglasses as a filter for one of four lovely snapshots.
Nacreous clouds float high above ordinary clouds at altitudes ranging from 9 to 16 miles. Their tiny ice crystals, which diffract sunlight to produce iridescent colors, need exceptionally low temperatures of minus 120 F to form. Because of these extremes, nacreous clouds are rare. Nevertheless, they have appeared several times this season over Scandinavia, raising hopes for more as the cold of winter deepens. The best time to look is around dusk and dawn.
more images: from Richt de Jong of Ørje, Norway; from Johannes Lillegaard Frøyen of Bogstad, Oslo, Norway; from Håkon Dahle of Fjellhamar, Norway; from David Milton of Angered, Sweden.
FORGET THE SKIING... Look for the halos! Ski slopes are excellent places to spot sundogs and other luminous ice halos, which appear when sunlight shines through ice crystals in the air.
Spaceweather reader Mike Conlan sends this report: "Last week, I was skiing on Blackcomb Mountain in Whistler, British Columbia, when I noticed a peculiar bright light below the sun with 'sundogs' on either side of it: photo. A snow storm was diminishing with about 60 km/h winds, so there was a large amount of small-particle snow blowing around." (continued below)
"My friends and I sat and watched the sundogs directly in front of us from the top of the world for quite a while! Luckily I was skiing with my Nikon D200 to capture this unique sight."
The lights that mesmerized Conlan's party are called subparhelia. "Ski slopes let us look downward to see halos normally located below the horizon," says atmospheric optics expert Les Cowley. "Here we have sub-horizon halos made by six-sided plate crystals."
People often think that 'sub-sundogs' are somehow reflections of true sundogs above. Not so, says Cowley. "They are not reflections of the sundogs but are formed by rays following sundog paths that, inside the crystal, happen to collide and reflect from a vertical crystal facet. The subsun directly below the sun can often also be seen on airplane journeys."