When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.
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EDGE OF SPACE CHRISTMAS CARDS: What do you give to the sky watcher who has everything? How about a Christmas card from the Edge of Space? For only $49.95, the students of Earth to Sky Calculus will fly your holiday greeting or favorite picture to the top of Earth's atmosphere, photograph it, and return the snapshot in time for the holidays. It's a unique gift! The group has previously flown cupcakes, shoes, US presidents, ad banners and telescopes. This holiday magic is performed using suborbital helium balloons. Contact Dr. Tony Phillips for more information.
GEMINID METEOR SHOWER--IT'S UNDERWAY: Last night, NASA's network of all-sky meteor cameras detected 47 Geminid fireballs over the United States. Even more are expected tonight as Earth passes through a stream of debris from rock comet 3200 Phaethon. "There is a nice show going on right now," says Bill Cooke, head of NASA's Meteoroid Environment Office. Cooke and other forecasters expect the shower to peak on Dec. 13-14. The best time to look is during the "magic hour" before sunrise on Saturday, Dec. 14th. [sky map]
The multiple cameras of NASA's fireball network are able to measure the orbits of the meteoroids it sees. Here are the orbits of last night's fireballs:
Earth is the blue dot where all the orbits intersect. The orbits are color-coded by velocity: blue is faster, red is slower. Note the cluster of yellow orbits. Those are Geminids. The other orbits in the diagram correspond to various minor showers and random ("sporadic") meteors. Takeaway: Not every meteor you see tonight will be a Geminid.
Theoretically, the Geminid peak could produce as many as 120 meteors per hour. However, glare from the nearly-full Moon could reduce the number of visible meteors 2- to 3-fold. Cooke advises looking during the hours just before local sunrise. "At that time, the Moon will be low or even below the horizon, improving your chances of seeing the show."
You can listen to radar echoes from the Geminids, unaffected by moonlight, on Space Weather Radio. Also, tune into NASA's live web chat about the Geminids on Friday the 13th beginning at 11 pm EST.
Realtime Meteor Photo Gallery
INCOMING CMES, CHANCE OF STORMS: Yesterday, December 12th, a pair of magnetic filaments on the sun erupted in quick succession between 0300 UT and 0630 UT. The explosions hurled a pair of coronal mass ejections (CMEs) into space. SOHO recorded the clouds racing away from the sun at approximately 1.1 million mph (500 km/s):
Although neither explosion was squarely Earth-directed, the two clouds could deliver glancing blows to Earth's magnetic field on Dec. 14th or (more likely) the 15th. NOAA forecasters estimate a 40% chance of polar geomagnetic storms when the clouds arrive. Aurora alerts: text, voice
Realtime Aurora Photo Gallery
ELECTRIC-BLUE CLOUDS OVER ANTARCTICA: The season for noctilucent clouds has begun in the southern hemisphere. NASA's AIM spacecraft is monitoring a vast bank of rippling electric-blue NLCs blanketing almost all of Antarctica. This two week movie chronicles the onset of the clouds in late November and their rapid spread into December:
NLCs are Earth's highest clouds. Seeded by "meteor smoke," they form at the edge of space 83 km above Earth's surface. When sunlight hits the tiny ice crystals that make up these clouds, they glow electric blue.
NLCs appear during summer because that is when water molecules are wafted up from the lower atmosphere to mix with the meteor smoke. That is also, ironically, the time when the upper atmosphere is coldest, allowing the ice crystals of NLCs to form.
In recent years NLCs have intensified. Some researchers believe this is a sign of climate change. One of the greenhouse gases that has become more abundant in Earth's atmosphere since the 19th century is methane. "When methane makes its way into the upper atmosphere, it is oxidized by a complex series of reactions to form water vapor," explains Hampton University Professor James Russell, the principal investigator of AIM."This extra water vapor is then available to grow ice crystals for NLCs."
Realtime Space Weather Photo Gallery
Comet ISON Photo Gallery
Realtime Comet Photo Gallery
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Dec. 13, 2013, the network reported 78 fireballs.
(47 Geminids, 24 sporadics, 3 December Monocerotids, 1 sigma Hydrid, 3 December Leonis Minorids)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Potentially Hazardous Asteroids (PHAs
) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones
all the time.
On December 13, 2013 there were 1446 potentially hazardous asteroids. Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| ||3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||the underlying science of space weather |