"I've never seen anything like it before," says photographer Maria Doty. "It was a very unusual sight and the colors were bright."

The technical name for this phenomenon is circumzenithal arc or "CZA" for short--and it's no rainbow. CZAs are formed by sunlight shining through plate-shaped ice crystals in high clouds. Atmospheric optics expert Les Cowley calls it "the most beautiful of all ice haloes." First timers often describe the CZA as an 'upside down rainbow' and "someone has also likened it to 'a grin in the sky,'" he adds.

Circumzenithal arcs typically appear in late autumn and early winter when the air is icy and the sun is low. "The CZA forms only when sun is less than 32.3° high," notes Cowley. As winter solstice approaches, "upside down rainbows" will become increasingly common. Look for them!

SUNSPOT 1033

11-22-09   Sunspot 1033  

Sunspot 1033 is a member
of new Solar Cycle 24.
Credit: SOHO/MDI

Earth is inside a solar wind
stream flowing from the indicated
coronal hole.
Credit: SOHO Extreme UV Telescope  

SOLAR ACTIVITY: The sun is coming to life. There are several new-cycle active regions scattered across the solar disk and the limb of the sun has some very photogenic prominences. Readers with solar telescopes should dust off their optics and take a look

Although the fireball appeared during the Leonid meteor shower, it was not a Leonid. Infrasound recordings of the blast suggest a small asteroid hitting Earth's atmosphere and exploding with an energy of 0.5 to 1 kiloton of TNT. Experts liken the event to the Park Forest fireball of 2003, which scattered dozens of meteorites across a suburb of Chicago. Meteorites are likely from this fireball as well. Stay tuned for developing information about the possible fall zone.

more fireball images: from KSL TV in Utah; from KTVB News in Idaho; from Thomas Ashcraft near Santa Fe, New Mexico; from Marsha Adams of Sedona, Arizona;

Approximately 6 hours after the fireball, people in Utah and Colorado got another surprise. As the sun rose over those states, a twisting electric-blue cloud appeared in the dawn sky:

"These curious clouds on the horizon caught my attention just before sunrise," says photographer Don Brown of Park City, Utah. "They were strangely bright relative to the rest of the sky."

The cloud strongly resembles artificial noctilucent clouds formed at high altitudes by rocket and shuttle launches. Yet there was no (officially reported) rocket launch at dawn on Nov. 18th. Could the cloud be associated with the fireball? The geographical coincidence is certainly striking. Debris from the fireball should have dissipated by sunrise, but the cloud remains unexplained and a connection to the fireball cannot yet be dismissed. Readers, if you have more information about this event, let us know.

more mystery cloud images: from Lisa Cain of New Castle, Colorado; from Daniel Owen of Monarch, Utah; from John Omohundro of Grand Junction, Colorado; from Jeff Kendrick of Salt Lake City, Utah; from Allan Jeffers of Denver, Colorado; from Scott Stringham of Salt Lake City, Utah; from Sean O'Leary of West Jordan, Utah;

UPDATED: 2009 Leonid Meteor Gallery
[previous Leonids: 1998, 2001, 2002, 2006]

A solar wind stream flowing
from the indicated coronal hole
should reach Earth on
Nov. 20th or 21st.
Credit: SOHO Extreme UV Telescope

The surge occurred when Earth passed through a double-stream of debris from Comet 55P/Tempel-Tuttle. We call it a "double-stream" because it consists of dust ejected from the comet on two occasions, in 1466 AD and 1533 AD. Earth is exiting the double-stream now, but we're not out of it yet. Be alert for Leonids between midnight and dawn: sky map.

more Leonid images: from Chris Peterson of Guffey, Colorado; from Andreas Gada of Oak Heights, Ontario; from Runar Sandnes of Reed, Norway; from Victor van Wulfen of Sutherland, South Africa; from Olivier Staiger in the Swiss Alps; from Malcolm Park of Grafton, Ontario, Canada;

Leonid resources:

• The 2009 Leonid Meteor Shower -- from Science@NASA
• 2001, 2002 Leonid storm galleries -- from Spaceweather.com
• Leonid sky map -- from Spaceweather.com
• Leonid activity reports -- from the International Meteor Organization

LISTEN: The Air Force Space Surveillance Radar is scanning the skies above Texas, and when a Leonid passes over the facility--ping!--there is an echo. Tune into Spaceweather Radio for a live audio feed.

2009 Leonid Meteor Gallery
[previous Leonids: 1998, 2001, 2002, 2006]

GOODBYE SUN: "The last week has been special with the sun rising in the south and setting in the south only an hour later," reports Fredrik Broms of Kvaløya, Norway. "But today (Nov. 16) the sun barely made it above the horizon." He photographed the few visible rays using a Nikon D3:

"Now sky watchers around the Arctic Circle enter the long polar night when the sun doesn't rise at all. How long this period lasts depends on your latitude. Here in northern Norway, the sun won't be back until the end of January."

"Goodbye sun, until 2010!"

Tiny sunspot 1031 is a member of new Solar Cycle 24.
 Credit: SOHO/MDI

SOLAR PROMINENCE: Yesterday, Alan Friedman of Buffalo, New York, trained his telescope on the sun and waited for sunspot 1029 to reappear. But that wasn't going to happen. It was shaping up to be a dull observing session when something completely different popped into view:

"This magnificent looping prominence stole the show from the corpse of sunspot 1029," says Friedman. "It was the most dramatic prominence I have seen in many months."

The same prominence was putting on a show this morning, Nov. 15th, when the sun rose over the Philippines. "I was elated when I was able to see it clearly visible in the field of my eyepiece!" reports James Kevin Ty from Manila. "I quickly set up my PST (Personal Solar Telescope) and was able to monitor the prominence for more than 2 hours."

The primary evidence is spectral. When LCROSS's Centaur rocket hit the ground, it produced a faint cloud of vapor. High above, the LCROSS mothership analyzed the cloud using its near-infrared spectrometer. Some of the bumps and wiggles in the spectrum perfectly match the infrared signature of H₂O:

The red curve traces what the spectrum would have looked like if the debris cloud had been made of nothing but moondust and pure water vapor. Points with error bars are the actual data. Clearly, water is present, but that's not all. "Along with the water in Cabeus, there are hints of other intriguing substances," says Anthony Colaprete, the mission's principal investigator the NASA's Ames Research Center. "The possibility of contamination from the Centaur rocket [has been] ruled out," so any unidentified compounds are likely native to the Moon.

What are these mystery substances? Remember, LCROSS targeted a "cold trap" where materials have been freezing and accumulating for billions of years. It could be almost anything. Researchers are still studying the spectra for clues. "Full understanding of the LCROSS data may take some time," notes Colaprete. "The data are so rich."

Current conditions

SOLAR ACTIVITY: Friday the 13th could be a lucky day for astrophotographers. A photogenic scene is developing on the sun's northeastern limb, where a magnetic thicket of hot plasma is rising into view. The Solar and Heliospheric Observatory (SOHO) made this movie of the action on Nov. 12th and 13th:

The swelling limb-glow heralds the approach of sunspot 1029, the biggest and most active sunspot of the year. Sunspot 1029 spent the past two weeks transiting the farside of the sun, invisible from Earth, but now it is about to reappear. Friday the 13th kicks off a 2- to 3-day photo-op as the sun's rotation slowly turns the active region back toward Earth. Readers with solar telescopes are encouraged to monitor developments.

Archival images of sunspot 1029: from Jimmy Eubanks of Boiling Springs, South Carolina; from Dave Gradwell of Birr, Ireland; from Pete Lawrence of Selsey, West Sussex, UK; from Paul Haese of Blackwood, South Australia

This is 1029 on the backside

The circle marks the location of sunspot 1029. In late October, sunspot 1029 materialized on the Earth-facing side of the sun and quickly established itself as the biggest active region of 2009. It produced more than ten C-class solar flares, single-handedly quadrupling the number of such eruptions since the year began. For the past 11 days, however, sunspot 1029 has been out of sight transiting the farside of the sun.

The sunspot is still invisible from Earth, but STEREO-B can see it because the spacecraft is stationed over the sun's eastern horizon. The glaring knot of extreme ultraviolet activity hides the sunspot's underlying dark core from STEREO's UV telescopes, and this limits how much we know about it. Has sunspot 1029 broken apart and diminished during its long farside transit? Or is it still its old active self? Answers will be revealed in 3 days when solar rotation turns sunspot 1029 toward white-light cameras on Earth.

Current conditions

"Pepper Dela Cruz took this picture outside the Miramar Restaurant in Half Moon Bay on the San Francisco Peninsula just as the sun was setting," says Doug Moore, who submitted the photo on Pepper's behalf. "It shows debris from the fireball, which lasted for several minutes before dissipating."

The origin of the fireball is still uncertain. Meteor expert Peter Jenniskens of NASA's Ames Research Center believes it was "a small, random asteroid that crashed into our atmosphere. The remains [of the space rock] probably landed in the Pacific Ocean," he says.

More fireballs are in the offing. Earth is passing through a stream of debris from Comet 2P/Encke, and this is causing the annual Taurid meteor shower, which peaks between now and Nov. 12th. The shower only produces about 5 meteors per hour, but what the display lacks in number, it makes up for in dazzle. Taurids tend to be fireballs, slow and very bright. The best time to look is during the hours around midnight when the constellation Taurus is high overhead: sky map.

Note: Based on the time of day and other factors, Jenniskens says "the Bay Area fireball was probably not a Taurid."

RETURNING SUNSPOT: The most active sunspot of the year, sunspot 1029, has spent the past week transiting the far side of the sun. It is still invisible from Earth, but the active region is coming into range of cameras onboard NASA's STEREO-B probe. The spacecraft beamed back this extreme ultraviolet image just hours ago:

A farside eruption on Nov. 5th (movie) suggests that the sunspot is still active. In late October, the last time we saw it on the Earth-facing side of the sun, sunspot 1029 unleashed more than 10 C-class solar flares, single-handedly quadrupling the total number of flares in all of 2009. The sun's rotation will turn the active region back toward Earth about four days from now. Until then, STEREO-B will keep us informed. Stay tuned.

BONUS: weekend solar images: from Pete Lawrence of Selsey, West Sussex, UK; from Alan Friedman of Buffalo, New York; from Jan Timmermans of Valkenswaard, The Netherlands

October Northern Lights Gallery
[previous Octobers: 2008, 2007, 2006, 2004, 2003, 2002, 2001]

Explore the Sunspot Cycle

MAGNETIC FILAMENT: Today, amateur astronomers are monitoring a picturesque magnetic filament looping around the western limb of the sun. Jan Timmermans sends this picture from his backyard observatory in Valkenswaard, The Netherlands:

The portion of the filament seen in front of the sun looks dark, because it is cooler than the inferno below. But note how the filament glows in projection against the black space beyond the limb. The glow comes from plasma trapped inside the filament--not as bright as the surface of the sun, but definitely brighter than the void.

"The image clearly shows that the only difference between a 'dark' filament and a 'bright' prominence is where they are located: inside or outside the solar disk," notes Timmermans. (diagram)

more images: from Alan Friedman of Buffalo, New York; from Stephen Ames of Hodgenville, Kentucky;

Sunspots are trying to emerge at the circled locations. They do not yet show up in SOHO white light images, but the active regions are clear in this magnetic map. Photo credit: SOHO/MDI

more images: from Pete Lawrence of Selsey, West Sussex; from Robert Arnold of Isle of Skye, Scotland
 

CME OF 11-5-09

The source of the eruption is probably sunspot 1029, which is transiting the far side of the sun. Last week, when sunspot 1029 was visible from Earth, it quickly grew into the biggest and most active sunspot of the year, unleashing ten C-class solar flares in just a few days. Apparently, the action hasn't stopped. The sun's rotation will turn the sunspot back toward Earth about a week from now. If the sunspot holds together that long, we could experience some solar activity. Stay tuned.

Current conditions

Red traces the distribution of sodium atoms detected by a spectrometer onboard MESSENGER. "The neutral sodium tail, so prominent in our first two flybys of Mercury, is now significantly reduced in extent," announced planetary scientist Ron Vervack at a NASA press conference yesterday.

The material in Mercury's tail comes from the surface of the planet itself, which is blasted by solar wind and micrometeorites. During MESSENGER's recent flyby of Mercury, the net effect of solar radiation pressure was small, and the sodium atoms were not accelerated away from the sun as they were during the earlier flybys, resulting in a diminished planetary tail. That's space weather. Get the full story from Science@NASA.

Photo credit: STEREO Extreme Ultra Violet Telescope (195 A)

This impressive sunspot, which rotated over the sun's western limb three days ago, does not add to the sunspot number because it is no longer visible from Earth. Astronomers only count spots that are on the Earth-facing side of the sun. That's how it's been done since Rudolph Wolf invented the sunspot number in 1848. In those days, only one side of the sun was visible from Earth, so the tradition was established.

Now, however, for the first time in the history of astronomy, NASA's twin STEREO spacecraft are seeing over the sun's horizon, tracking sunspots that officially "don't count." The two spacecraft are moving toward opposite sides of the sun, and by February 2011 the entire sun will be under their watchful eyes. Perhaps it is time to start thinking about a "whole sun" sunspot number. As today's image shows, the sun is not always as blank as it appears to be.

Next, point a telescope at the red planet and you'll see a surprising splash of icy blue:

"Mars' north polar cap is big enough and bright enough to be seen though most backyard telescopes at medium to high power," says Joel Warren of Amarillo, Texas, who took the picture, above, on Halloween using an 11 inch Celestron telescope.

On Mars, northern winter has just ended and clouds which normally hover over the martian arctic are breaking up, allowing the planet's great ice cap to be seen. "This apparition will offer observers the best view of the North Polar Region to be had in many years," notes Warren.

more images: from Peter Garbett of Sharnbrook, UK; from Rolando Ligustri of Italy using a remotely-controlled telescope in New Mexico; from Ed Lomeli of Sacramento, California;

The blast reinforces sunspot's 1029's position as the most active sunspot of 2009. Last week alone, the sunspot produced ten C-class solar flares, more than tripling the number of flares in the previous 10 months. Sunspot 1029 is a member of long-overdue Solar Cycle 24. Is it also a herald of more active times to come?

SEE OCTOBER PAGE FOR LARGER IMAGE.

A solar wind stream flowing from
 the indicated coronal hole should
reach Earth on or about Nov. 6th.
Credit: SOHO Extreme UV Telescope

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