AURORA ALERTS: Did you miss the Northern Lights? Next time get a wake-up call from Space Weather PHONE

SUNDIVING COMET: A newly-discovered comet is diving toward the sun. Chinese comet hunter Bo Zhou found it on Oct. 19th in SOHO coronagraph images. The comet is faint now, but it should brighten in the hours ahead as it heats up. To see it, first check the finder chart, then play the latest movie. That tadpole is a doomed comet. Updates will be posted as the view improves.

ORIONID METEOR SHOWER: Earth is entering a broad stream of debris from Halley's Comet, and this is causing the annual Orionid meteor shower. "The best time to look is during the hours before dawn on Thursday, Oct. 21st, and again on Friday, Oct 22nd," advises Bill Cooke of NASA's Meteoroid Environment Office. "Unfortunately, we have a bright Moon this year. Even so, I'd expect some bright Orionids to shine through the moonlight." An all-sky camera at the University of Western Ontario recorded this early Orionid fireball on Oct. 18th:

Orionid meteors stream from the elbow of Orion the Hunter: sky map. Because the shower's radiant point is close to the celestial equator, sky watchers in both hemispheres can enjoy the show. Moonlit meteor rates will probably be around a dozen per hour.

Radar rates could be much higher. The US Air Force Space Surveillance Radar in Texas is scanning the skies for satellites, space junk, and meteoroids. When an Orionid passes overhead--ping!--there is an echo. Moonlight does not interfere with this method of meteor observing, so it's perfect for this year's Orionids. Tune into Spaceweather Radio for live echoes.

Orionid images: from John Chumack of Dayton, Ohio; from Calvin Hall of Knik Valley, near Palmer Alaska; from Martin Popek of Nýdek, Czech republic

TIME TO SEE COMET HARTLEY: For backyard stargazers, now is the best time to see green Comet 103P/Hartley 2 as it approaches Earth for an 11-million-mile close encounter on Oct. 20th. Set your alarm for the dark hours before dawn, go outside, and look straight up. You will find Hartley 2 not far from the bright star Capella: sky map. Although the comet is barely visible to the unaided eye, it is easy to find in binoculars and looks great through a backyard telescope.

"I observed Comet Hartley 2 at dawn on October 20, 2010, at its closest approach to Earth," says amateur astronomer Alan Dyer, who sends this picture from a dark-sky site near Cluny, Alberta, Canada:

"Apart from the blue-green color, this view matches what the comet looked like visually through large binoculars — a round fuzzball," says Dyer.

Many readers have asked, why is the comet green? Answer: Hartley 2's green color comes from the gases that make up its Jupiter-sized atmosphere. Jets spewing from the comet's nucleus contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C₂). Both substances glow green when illuminated by sunlight in the near-vacuum of space.

NASA scientists say 103P/Hartley 2 is one of the most active comets they've seen, with copious outgassing from jets in the nucleus. Amateur astronomers are encouraged to monitor the action and submit their images here.

more images: from Doug Zubenel near Onaga, Kansas.; from Paul Klauninger of Marathon, Ontario, Canada; from Jimmy Westlake of Stagecoach, Colorado; from Nick Howes of Cherhill, Wiltshire, UK; from Abe Schwartz of San Juan, Puerto Rico; from Dr Paolo Candy of Ci.A.O. Cimini Astronomical Observatory - Italy; from John Chumack of Dayton, Ohio; from Keith Johnson of Durham, England,UK; from Joao Porto of Ponta Delgada, Azores islands, Portugal

---

October 2010 Aurora Gallery
[previous Octobers: 2009, 2008, 2007, 2006, 2004, 2003, 2002, 2001]

Near Earth Asteroids

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. 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.

Essential web links

NOAA Space Weather Prediction Center

The official U.S. government space weather bureau

Atmospheric Optics

The first place to look for information about sundogs, pillars, rainbows and related phenomena.

Solar Dynamics Observatory

Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever.

STEREO

3D views of the sun from NASA's Solar and Terrestrial Relations Observatory

Solar and Heliospheric Observatory

Realtime and archival images of the Sun from SOHO.

Daily Sunspot Summaries

from the NOAA Space Environment Center

Heliophysics

the underlying science of space weather

Science Central

more links...