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. | | | M-CLASS SOLAR FLARES: Big sunspot AR1899 is crackling with M-class solar flares. Because the active region is approaching the sun's western limb, however, none of these flares are squarely Earth directed. Geoeffective solar activity is expected remain low this weekend. Solar flare alerts: text, voice COMET ISON LIVES UP TO THE HYPE: Comet ISON is now only 5 days from perihelion. On Nov, 28th, Thanksgiving Day in the USA, it will fly through the sun's atmosphere little more than a million kilometers above the surface of the sun. At closest approach, the temperature of ISON's core could rise as high as 5000o Fahrenheit--an existential challenge for an icy comet. No one knows if it will survive. As the "final countdown" ticks to zero, photographers are taking some marvelous parting shots. Here is Comet ISON plunging into the sunrise beside Mt. Fuji on Nov. 22nd: Japanese photographer Kagaya took the picture using a Canon EOS 1D C digital camera. "This is a 3-second exposure at ISO 2000," he says. In the full-sized image, you can also see Mercury hovering to the left of the comet. For more unique images of Comet ISON, including a Nov. 23rd daytime shot from Los Angeles and a conjunction with the Temple of Poseidon in Greece, browse the realtime photo gallery: Realtime Comet ISON Photo Gallery Ephemerides: Comet ISON, Comet Lovejoy, Comet Encke, Comet LINEAR X SOLAR FLEET PICKS UP COMET ISON: Because NASA's twin STEREO probes are designed to observe the sun, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager. Click on the image to view ISON's grand entrance: "The dark 'clouds' of stuff you see coming from the right are density enhancements in the solar wind, and these are what are causing all the ripples you see in comet Encke's tail," explains Karl Battams of NASA's Comet ISON Observing Campaign. "I can pretty much promise you that we're going to see ISON's tail doing that in a couple of day's time, but on a much larger scale!" Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. "No they're not going to hit each other - in reality they are millions of miles apart - but as seen from the STEREO-A spacecraft, they are going to get very close!" he says. "We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement." Stay tuned for that. Realtime Comet ISON Photo Gallery Realtime Space Weather Photo Gallery Realtime Aurora Photo Gallery Realtime Comet ISON 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 Nov. 23, 2013, the network reported 6 fireballs. (6 sporadics) 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 November 23, 2013 there were 1439 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 | |