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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RARE DOUBLE-COMET FLYBY OF MERCURY: NASA's MESSENGER spacecraft is about to get a close-up view of Comet ISON's outburst. On Nov. 18-19 Comet ISON and Comet Encke both will fly by Mercury, the planet MESSENGER is orbiting. You can learn more about this rare double-comet flyby and what MESSENGER might see in a video from Science@NASA.
COMET ISON OUTBURST CONTINUES: The abrupt brightening of Comet ISON on Nov. 14th has pushed the comet into the range of naked eye visibility. Dark-sky observers around the world report seeing it with their unaided eyes on the morning of Nov. 15th. To the human eye, ISON is just a faint smudge of magnitude +5.5. Backyard telescopes are revealing much more. The effects of the outburst have propagated into the comet's suddenly riotous tail, as shown in this image taken on the morning of Nov. 15th by Damian Peach:
"It's hard to believe this is the same comet I photographed on Nov. 10th," says Peach. "Now that ISON has experienced an outburst, the show has really begun."
The increase in brightness and emergence of multiple gaseous streamers could be caused by fresh veins of ice opening up in the comet's nucleus. Rapid vaporization of ice by solar heat is a sure-fire way to boost a comet's visibility. But, as NASA's Comet ISON Observing Campaign states, "we have no idea." The comet's nucleus is hidden from view by a hazy green atmosphere, so events in the interior remain a mystery.
"I have a strong suspicion that this is Comet LINEAR (C/1999 S4) all over again," says Mark Kidger of the ESA's European Space Astronomy Centre in Madrid. In the year 2000, Kidger other astronomers monitored Comet LINEAR as it disintegrated en route to the sun. "The sudden appearance of ISON's gas tail, the increasing fuzziness of its coma, and now this sudden outburst all remind me of C/1999 S4 just before it broke apart."
To reiterate: No one knows what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).
Monitoring is encouraged. Comet ISON rises in the east just before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Dates of special interest include Nov. 17th and 18th when the comet will pass the bright star Spica, making ISON extra-easy to find. Sky maps: Nov. 15, 16, 17, 18, 19.
Realtime Comet ISON Photo Gallery
Ephemerides: Comet ISON, Comet Lovejoy, Comet Encke, Comet LINEAR X1
SUNSPOT SUNRISE: The sunspot number is so high, it is starting to confuse photographers. Consider this story from Beijing, China, on the morning of Nov. 15th: "Beijing is usually very polluted and we often miss seeing the sun rise in the morning," says Shalini Purohit. "Today, however, the morning sky was clear and I decided to take some pictures. When I looked at the image I thought there must be come specks of dust on my lens." In fact, the lens was clean; those specks were sunspots:
When the sunspot number is high, so is the chance of flares. NOAA forecasters estimate a 50% chance of M-class flares and a 15% chance of X-flares during the next 24 hours. As Purohit's image shows, at least four of the sun's spots are facing Earth. If any eruptions do occur, they will likely be geoeffective. Solar flare alerts: text, voice
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. 15, 2013, the network reported 14 fireballs.
(8 sporadics, 4 Northern Taurids, 1 omicron Eridanid, 1 November omega Orionid)
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 15, 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 |