HALLOWEEN FLARES: After two days of quiet, big sunspot 1117 is once again crackling with solar flares. Magnetic fields around the active region became unstable on Oct. 31st, unleashing a C2-class flare at 0318 UT and a C6-class flare at 0431 UT. Stay tuned for movies.

DEAD SPACECRAFT WALKING: Two NASA spacecraft that were supposed to be dead a year ago are instead flying to the Moon for a breakthrough mission in lunar orbit. The research they conduct could lead to important advances in space weather forecasting. For more information, read "Dead Spacecraft Walking" from Science@NASA.

Oct. 27, 2010:  A pair of NASA spacecraft that were supposed to be dead a year ago are instead flying to the Moon for a breakthrough mission in lunar orbit.

"Their real names are THEMIS P1 and P2, but I call them 'dead spacecraft walking,'" says Vassilis Angelopoulos of UCLA, principal investigator of the THEMIS mission. "Not so long ago, we thought they were goners. Now they are beginning a whole new adventure."

An artist's concept of THEMIS-P1 and P2 (since renamed ARTEMIS-P1 and P2) in lunar orbit. [larger image]

The story begins in 2007 when NASA launched a fleet of five spacecraft into Earth's magnetosphere to study the physics of geomagnetic storms. Collectively, they were called THEMIS, short for "Time History of Events and Macroscale Interactions during Substorms." P1 and P2 were the outermost members of the quintet.

Working together, the probes quickly discovered a cornucopia of previously unknown phenomena such as colliding auroras, magnetic spacequakes, and plasma bullets shooting up and down Earth’s magnetic tail. These findings allowed researchers to solve several longstanding mysteries of the Northern Lights.

In their previous life, THEMIS-P1 and P2 were on a mission to study Northern Lights. [more]

The mission was going splendidly, except for one thing: Occasionally, P1 and P2 would pass through the shadow of Earth. The solar powered spacecraft were designed to go without sunlight for as much as three hours at a time, so a small amount of shadowing was no problem. But as the mission wore on, their orbits evolved and by 2009 the pair was spending as much as 8 hours a day in the dark.

"The two spacecraft were running out of power and freezing to death," says Angelopoulos. "We had to do something to save them."

The team brainstormed a solution. Because the mission had gone so well, the spacecraft still had an ample supply of fuel--enough to go to the Moon. "We could do some great science from lunar orbit," he says. NASA approved the trip and in late 2009, P1 and P2 headed away from the shadows of Earth.

With a new destination, the mission needed a new name. The team selected ARTEMIS, the Greek goddess of the Moon. It also stands for "Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun."

The first big events of the ARTEMIS mission are underway now. On August 25, 2010, ARTEMIS-P1 reached the L2 Lagrange point on the far side of the Moon. Following close behind, ARTEMIS-P2 entered the opposite L1 Lagrange point on Oct. 22nd. Lagrange points are places where the gravity of Earth and Moon balance, creating a sort of gravitational parking spot for spacecraft.

POSSIBLE METEORS FROM COMET HARTLEY 2: A pair of unusual fireballs over Canada and the southeastern USA have experts wondering if Comet Hartley 2 might produce a meteor shower in early November. Get the full story from Science@NASA.

BIG BRIGHT OBJECT NEAR THE SUN: Don't panic, it's just Venus. The brilliant evil twin of Earth is passing between our planet and the sun this week, making a bright UFO-like light in SOHO coronagraph images:

The bright rays and luminous bloom centered on the planet are digital artifacts. Venus is so bright, it saturates SOHO's CCD detectors, causing electrons to "bleed" across pixel boundaries. The same thing happens to a lesser degree with Mercury, which is bisected by a horizontal bar--another artifact. Note how the star Spica, dimmer than the planets, appears as a normal pinprick. It does not saturate the CCD.

Venus will continue its flamboyant passage for the next few days. Join SOHO for a ringside seat.

A BIG SUNSPOT GETS BIGGER: Behemoth sunspot 1117 is not merely growing, it is transmogrifying. Click on the image to launch a two-day movie from NASA's Solar Dynamics Observatory (8 MB):

Since yesterday, the shape-shifting sunspot has developed a "beta-gamma" magnetic field that harbors energy for M-class solar flares. Any such eruptions will likely be geoeffective because the sunspot is almost-squarely facing Earth. Readers with solar telescopes are encouraged to monitor developments.

more images: from Rogerio Marcon of CASLEO Observatory, San Juan, Argentina; from Patrick Bornet of Saint Martin sur Nohain, Nièvre, France; from David Arditti of Edgware, UK; from John Stetson of Portland, Maine

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

10-27-10  Solar wind speed: 495.7 km/sec density: 1.1 protons/cm3 explanation | more data Updated: Today at 2006 UT X-ray Solar Flares 6-hr max: B7 1705 UT Oct27 24-hr: B7 1705 UT Oct27 explanation | more data Updated: Today at: 2005 UT

FAST-GROWING SUNSPOT: Sunspot group 1117 more than tripled in size over the weekend: SDO movie. The active region has not yet produced a major eruption, but it is crackling with picturesque B-class solar flares. Stay tuned for updates.

AURORA ALERT: High-latitude sky watchers should be alert for auroras. A high-speed solar wind stream is buffeting Earth's magnetic field and causing polar geomagnetic storms.

THE SURPRISING CONTENTS OF LUNAR CRATERS: Nearly a year after announcing the discovery of water molecules on the moon, scientists say there's more than just water hiding in cold lunar craters. Get the full story from Science@NASA.

SUNDIVING COMET: The solar system now has one less comet. Earlier today, a sundiving comet discovered on Oct. 19th by Chinese amateur astronomer Bo Zhou passed too close to the sun and apparently evaporated. A coronagraph onboard the Solar and Heliospheric Observatory (SOHO) recorded the death plunge:

The comet was likely a member of the Kreutz sungrazer family. Named after a 19th century German astronomer who studied them in detail, Kreutz sungrazers are fragments from the breakup of a giant comet at least 2000 years ago. Several of these fragments are thought to pass by the sun and disintegrate every day. Most are too small to see but occasionally a big fragment like this one attracts attention

ASTEROID FLYBY: Asteroid 2010 TG19 is flying past the Earth-Moon system today, Oct. 22nd, only 24,000 miles beyond the orbit of the Moon. The 70-meter space rock is about twice the size of the asteroid or comet that flattened a forest in Siberia in 1908. In this case, however, there is no danger of a collision.
Astronomers at the Sormano Astronomical Observatory in Italy photographed the asteroid's approach on Oct. 21st using a 20-inch telescope: image.

Solar wind
speed: 372.5 km/sec
density: 2.4 protons/cm³
explanation | more data
Updated: Today at 0315 UT X-ray Solar Flares
6-hr max: B3 1910 UT Oct21
24-hr: B3 1910 UT Oct21
explanation | more data
Updated: Today at: 2355 UT

ORIONID METEOR UPDATE: Earth is exiting a stream of debris from Halley's Comet, the source of the annual Orionid meteor shower. According to preliminary counts from the International Meteor Organization, the shower peaked on Oct. 21st with 35 meteors per hour. Here are some of them: #0, #1, #2, #3. Activity should continue at reduced levels for another day or two with continued interference from the bright Moon. Listen for stragglers at Spaceweather Radio.

MEGA SOLAR FILAMENT: An awesome, monstrous, jaw-dropping, 400,000 km long filament of magnetism is stretched across the sun's southern hemisphere. If it collapses or erupts, as filaments often do, the result could be an Earth-directed coronal mass ejection. Meanwhile it is a fine target for backyard solar telescopes.

FILAMENT UPDATE: Magnetic instabilities in the filament caused an eruption today around 1600 UT. The filament was not destroyed, nor was material hurled toward Earth. SDO movies: mpeg, m4v.

SOLAR FLARES: Fast-growing sunspot 1112 is crackling with solar flares. SDO movies show the three strongest of the past 24 hours: an M3-flare @ 1910 UT on Oct. 16th, a C1-flare @ 0900 UT and another C1-flare @ 1740 UT on Oct. 17th. So far, none of the blasts has hurled a substantial CME toward Earth.

The filament is filled with relatively dense plasma held above the stellar surface by magnetic forces. Because this plasma is cooler than the sun below, it appears dark. In fact, it is not. If you could hold the filament out against the black of space, it would glow more brightly than a full Moon.

The 400,000-km scale of the filament--long enough to stretch from Earth to the Moon!--makes it an easy target for safely-filtered backyard optics. If you have a solar telescope, take a look.

more images: from Stephen Ramsden of Immaculate Heart of Mary Catholic School, Atlanta, GA; from Jean-Pierre Brahic of Uzès ( France); from Michael Boschat of Halifax,Nova Scotia,Canada; from James Kevin Ty of Manila , Philippines; from the Solar Dynamics Observatory in Earth orbit; from Didier Favre of Brétigny-sur-Orge, France; from Ron Cottrell of Oro Valley, Arizona;

COMET HARTLEY UPDATE: "Comet 103P/Hartley 2 is growing at an amazing rate," reports Nick Howes of Cherhill, Wiltshire, UK. "The comet's atmosphere (coma) is now more than 1^o wide." He took this picture on Oct. 13th using the 2-meter robotic Faulkes North Telescope in Hawaii:

Comet Hartley is approaching Earth for an 11-million-mile close encounter on Oct. 20th. Although it is barely visible to the naked eye, the comet looks great through backyard telescopes. The best time to look is during the dark hours before sunrise when the comet is almost straight overhead in the constellation Perseus. Check Sky & Telescope for a sky map and more.

Need a telescope for Comet Hartley 2? We recommend the David H. Levy Comet Hunter, specifically designed by comet-master David Levy for times like these.

more images: from Rolando Ligustri using a robotic telescope in New Mexico; from Mike Broussard of Maurice, Louisiana; from Fredrik Broms of Kvaløya, Norway; from Tamás Ábrahám of Zsámbék, Hungary; from Efrain Morales Rivera of Aguadilla, Puerto Rico; from P-M Hedén of Vallentuna, Sweden;

PHOTOGENIC SUNSPOT: An enormous magnetic filament is perched directly above sunspot 1112 near the sun's southeastern limb. If the filament collapses (as they often do) and hits the sunspot below, the resulting explosion could be impressive. Actually, it's already impressive:

Dutch amateur astronomers Jo Dahlmans and Wouter Verhesen took the picture yesterday using a Lunt solar telescope. "We inverted (made negative) the sun's surface for a stunning display of the snaking filament," says Dahlmans. "In the distance you can see prominences dancing like flames along the limb of the sun. What a vista!"

Readers with solar

Readers with solar telescopes, you know what to do.

more images: from Dave Gradwell of Birr, Ireland; from Jimmy Eubanks of Boiling Springs, SC; from Robert Arnold of Isle of Skye, Scotland; from James Kevin Ty of Manila, Philippines; from Michael Buxton of Ocean Beach, California; from Gianfranco Meregalli of Milano, Italy

ASTEROID FLYBY--DONE! Asteroid 2010 TD54 flew past Earth this morning (Oct. 12) at 6:50 am EDT only 46,000 km above the planet's surface. For comparison, geosynchronous satellites orbit at 36,000 km, so the asteroid was not far beyond Earth's satellite fleet. No damage was done--to spacecraft or to the planet below. Amateur astronomer Patrick Wiggins photographed the flyby using a 14-inch Celestron telescope: movie.

ACTIVE REGION 1112: Emerging sunspot 1112 is connected to a vast network of dark magnetic filaments looping around the sun's southeastern limb. NASA's Solar Dynamics Observatory took this picture of the region just hours ago:

Filaments such as these have a habit of erupting. Will the fact that they are rooted in a sunspot make them more--or less--stable? No one knows. The magnetohydrodynamics of sunspots is so complex, not even the most powerful supercomputers on Earth can predict when they will erupt. Readers with solar telescopes are encouraged to monitor this region for unexpected developments.

more images: from Ingmar Glass of Bavaria, Germany; from Cai-Uso Wohler of Bispingen, Germany; from Larry Alvarez of Flower Mound, Texas

FARSIDE BLAST: Old sunspot 1109 on the farside of the sun erupted during the late hours of Oct 8th, producing a CME and a solar tsunami. NASA's STEREO-A spacecraft recorded this movie of the blast. Earth will not be affected by these events.

COMET HARTLEY UPDATE: As comet 103P/Hartley 2 approaches Earth for an 11-million-mile close encounter on Oct. 20th, it grows bigger and bigger in backyard telescopes. The comet's beautiful green atmosphere now subtends an angle approcimately equal to a lunar sea:

Paul Klauninger of Marathon, Ontario, took the picture on Oct. 2nd using a 3-inch refracting telescope. "I photographed the Moon with the same set-up and placed it beside the comet for scale," he says. "In a five minute exposure the comet appears bright green and 7-8 arcminutes across."

Most observers agree that the comet is not yet

10-3-10  sybsoit 1111 us growing

Solar wind
speed: 282.1 km/sec
density: 0.1 protons/cm³
explanation | more data
Updated: Today at 2340 UT X-ray Solar Flares
6-hr max: B1 2145 UT Oct03
24-hr: B2 0435 UT Oct03
explanation | more data
Updated: Today at: 2340 UT

COMET HARTLEY 2 UPDATE: Is Comet Hartley 2 sprouting a tail? A series of five-minute integrations taken last night by Gregg Ruppel of Ellisville, Missouri, seems to show a growing elongation of the comet's atmosphere: images.

He caught the comet gliding by lambda Cassiopeia, a 6th magnitude double star. "In 7x50 binoculars, the comet is diffuse and very large," says Scarmato. "I estimate its size around 20-arcminutes and brightness at magnitude +7.5."

Two weeks after Comet Hartley has its close encounter with Earth, NASA will have a close encounter with the comet. The EPOXI spacecraft (formerly known as Deep Impact) is hurtling toward Comet Hartley now, and on Nov. 4th it will fly 435 miles from the comet's active icy nucleus. The encounter will mark only the fifth time in history that a spacecraft has been close enough to image a comet's core.

Until then, amateur astronomers can monitor the comet as it glides through the constellation Cassiopeia in the evening sky. A finder chart from Sky and Telescope shows the comet passing by a variety of stars and deep-sky objects, offering many photo-ops in the nights ahead.

more images: from Michael Jäger of Stixendorf Austria; from P-M Hedén of Vallentuna, Sweden; from Mike Broussard of Maurice, Louisiana; from Rolando Ligustri observing remotely from New Mexico; from Mike Holloway of Van Buren, Arkansas;