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. | | | LAST-MINUTE GIFT IDEA: Would you like to give someone a solar flare for Christmas? There's still time. Gift subscriptions to our Space Weather Alert Service are available now. Sign up for text or voice. Merry Christmas! CHRISTMAS CONJUNCTION IN SPACE: According to some scholars, the Star of Bethlehem might have been a close encounter between Venus and Jupiter. The two brightest planets in the night sky, merged, would have made a spectacle of Biblical proportions. This Christmas, NASA's STEREO-B probe is observing a conjunction of three planets--Venus, Earth and Jupiter:  Unlike conjunctions of the distant past, this one includes our home planet. STEREO-B is located on the far side of the sun where it can look back and see Earth along with other worlds in the Solar System. Only NASA's twin STEREO probes, equipped with their high dynamic-range Heliospheric Imagers, can witness this kind of conjunction. From STEREO-B's point of view, Earth and Jupiter are less than 0.4 degrees apart, while all three planets fit in a circle 2 degrees in diameter. This meeting is not nearly as tight as the putative Star of Bethlehem conjunction ~2000 years ago. At that time Venus and Jupiter could have been as little as 6 arcseconds (0.00166 degrees) apart. Nevertheless, the ongoing display is still special because it's the first "Christmas Star conjunction" from space. Happy Holidays from STEREO! Realtime Space Weather Photo Gallery CRESCENT VENUS: Wondering where to point that telescope you got for Christmas? Here's a target that will blow your holiday socks off: Venus. Like the Moon, Venus has phases, and at the moment it is a slender crescent. Maximilian Teodorescu sends this Christmas Eve photo from Targoviste, Romania:  "I enjoyed another superb sunset with Venus dominating the southwestern sky," says Teodorescu. "The bright planet was visible even through cirrus clouds. Despite poor seeing conditions, the view through my refracting telescope was superb both at 30x and at 200x." Every night the crescent grows thinner as Venus moves toward inferior conjunction with the sun in early January. Tonight, only 10% of the planet's illuminated hemisphere is visible from Earth. Because Venus is so thin, refraction in our atmosphere can produce a rainbow effect as colorful as any Christmas ornament. It really is a magical sight. More information is available from Sky and Telescope. Realtime Venus Photo Gallery Realtime Aurora 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. 25, 2013, the network reported 14 fireballs. (13 sporadics, 1 December Leonis Minorid)  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 25, 2013 there were 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 | |