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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QUIET SUN: The sun's southern hemisphere is peppered with sunspots, but none of them is actively flaring. Solar activity remains low. NOAA forecasters estimate a 15% chance of M-class solar flares and a scant 1% chance of X-flares on Dec. 5th. Solar flare alerts: text, voice
SUNSET SKY SHOW: When the sun goes down tonight, step outside and look southwest. The crescent Moon and Venus are converging for a beautiful close encounter. These are the two brightest objects in the night sky and they pop out of the twilight long before the sky fades to black. Erwin Matys and Karoline Mrazek of Project Nightflight photographed the pair converging over the Canary island El Hierro on Dec. 4th:
They'll be even closer together tonight. With less than 10o of arc seperating the two, they would fit together inside the bowl of the Big Dipper.
If you have binoculars or a small telescope, take a closer look at the heavenly bodies. Both are crescents. Like the Moon, Venus has phases and tonight it is 27% illuminated. For comparison, the lunar crescent is half as wide, about 13.5%.
Bonus: This week Venus is at its brightest for 2013, shining almost 200 times brighter than a 1st-magnitude star. That's why it is so easy to see before darkness falls. Look southwest as soon as the sun sets. A Venus-Moon conjunction surrounded by twilight blue is one of the most beautiful sights in the heavens.
Realtime Space Weather Photo Gallery
WHO NEEDS COMET ISON? Astronomers are mourning the loss of Comet ISON, which disintegrated when it flew past the sun on Thanksgiving Day (Nov. 28). Who needs it? There is another comet brightening in the morning sky--naked-eye Comet Lovejoy (C/2013 R1). Martin McKenna sends this report from Northern Ireland: "This morning, the comet was easily visible as a fuzzy star of 4th magnitude with a long straight tail between the constellations Bootes and Hercules." He took this picture using a Canon 450D digital camera:
"I could see 5 degrees of tail with my unaided eye," continues McKenna. "Using the camera the tail was at least 10o long!"
Telescopes and longer exposures reveal much more. This image from Michael Jäger of Masenberg, Austria, shows a "disconnection event" disrupting the comet's tail on Dec. 5th. The disturbance could be caused by a gust of solar wind or perhaps an episode of vigorous outgassing in the comet's core.
Monitoring is encouraged. Comet Lovejoy is easy to find before dawn rising in the east before the sun. Sky maps: Dec. 6, 7, 8, 9.
Realtime Comet Photo Gallery
Realtime Aurora 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. 5, 2013, the network reported 5 fireballs.
(3 sporadics, 1 sigma Hydrid, 1 Geminid)
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 5, 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 |