ROBOTS PLOT TO DESTROY SPITZER SPACE TELESCOPE: It must be true, because the video comes directly from the Spitzer Science Center at Caltech. Tune in here to see how power-hungry robots are plotting to destroy one of NASA's greatest observatories.

EMPTY ERUPTION: Yesterday, Sept. 29th around 0830 UT, a translucent filament of magnetism rose up from the sun's northeastern limb and erupted. NASA's Solar Dynamics Observatory recorded the action. Click on the image to launch a five hour time-lapse movie--and keep an eye on the ghostly loop:

CRACKLING SUNSPOT: During the past 24 hours, sunspot 1110 has increased in size more than 10-fold. A white-light camera onboard NASA's Solar Dynamics Observatory took this picture during the early hours of Sept. 29th:

Although it is still small compared to behemoth sunspot 1109 right behind it, sunspot 1110 is much more active. Reconnection events in the sunspot's magnetic canopy have produced at least two C-class solar flares since yesterday (SDO movies: #1, #2). The eruptions were brief and did not hurl significant clouds of plasma toward Earth. If the sunspot continues to grow, however, future eruptions could become geoeffective.

"Now we know," says Seguin, "what it would look like if Jupiter and the sun had a child."

Seriously, this is a composite of multiwavelength images and a magnetogram taken by SDO just as the sun was emerging from its daily blackout. "Magnetograms are computed from a series of images taken over a short time span. The ribbons of color result from Earth's motion across the sun during the series of exposures."

Seguin has prepared a movie showing what an eclipse looks like at one of SDO's extreme ultraviolet wavelengths: click to play. "Eclipse season will be over on Oct. 6th," he says. Meanwhile, stay tuned for strange.

Mila Zinkova took the picture overlooking San Francisco Bay. "The sun and sunspot 1109 were constantly changing shape as the sun set," says Zinkova. "It was wonderful. A small green flash at the end added nicely to the mood." Click here to view the complete sunset sequence.

Sunspot 1109, which stretches more than 100,000 km from end to end, is slowly growing as it transits the solar disk. The forecast calls for another week of sunset sunsets before the region disappears over the sun's western limb.

more images: from Aymen Ibrahem of Miami, Alexandria, Egypt; from Konstantinos Christodoulopoulos of Agioi Theodoroi beach, Korinthia, Greece

TRIPLE RAINBOW: Double rainbows are commonplace. Sunlight reflected once inside raindrops produces the primary arc; sunlight reflected twice produces the secondary. Most people who have seen a single rainbow, have also seen a double.

But have you ever seen a triple? Daryl Pederson of Anchorage, Alaska, spotted one on Sept. 20th:

Here's something you don't see every day--three rainbows at once!" says Pederson. "The bonus third rainbow was caused by an image of the sun reflected from Potter's Marsh into the falling rain above."

Three rainbows is not the record, however. Atmospheric optics expert Les Cowley has documented cases of four, five and even six bows in the same scene. Read all about them here.

more images: from Calvin Hall of Beluga Point near Anchorage Alaska; from John Maynard of Mt. Rushmore, South Dakota; from Jeff Berkes of Kilo, Hawaii; from Marko Korosec of Dolenja vas, Senozece, Slovenia, Europe; from Alan Dyer of Cluny, Alberta, Canada; from Slanec Erich of Vienna, Austria

AUTUMN SUNRISE: Today in Veszprem, Hungary, photographer Monika Landy-Gyebnar woke up early and went outside at dawn to photograph the first sunrise of autumn. "The distant valley fog was painted pink and orange by the colors of the rising sun," she says. "Later, when I was looking closely at the pictures, I also found a couple of sunspots."

Sunspots 1108 and 1109 have grown so large, they can now be seen without the amplification of a solar telescope. NOAA forecasters estimate a 10% chance of an M-flare from one of these behemoths in the next 24 hours, and that could lead to fall colors of a different kind--Northern Lights. "Autumn is my favourite season and it seems to be getting off to a good start!" says Landy-Gyebnar.

"The sight of this Super Harvest Moon beaming through the trees, inflated to gargantuan proportions by the Moon illusion, made me feel like howling," says photographer Vasilis Wooseas of Greece. Onlookers elsewhere felt the same way. Browse the links below for examples.

more images: from Doug Zubenel of De Soto, Kansas; from Jan Lameer at Amsterdam harbour, the Netherlands; from Dave Lengyel of Brighton township, Ohio; from Monika Landy-Gyebnar of Veszprem, Hungary; from Malcolm Park of Columbus, Ontario; from Bob Collins of Ormond Beach, FL; from Dusty Hicks of Nowata , Oklahoma; from Adrian New of San Antonio, Texas; from Robert Schalck of North Bend, Oregon

It took 23 seconds to cross the sky and was nearly as bright as the full Moon," says Thomas Ashcraft, who operates the camera. "The fireball made a sonic boom loud enough to be heard inside above fan noise and household din. At first I thought it was thunder."

After passing over New Mexico, the fireball apparently continued on to Texas. "At 10:05 pm CDT (9:05 pm MDT) on Sept. 21st we witnessed a slow-moving fireball entering from the west and headed ENE," reports Matthew Byrd of Amarillo. "It was very bright white and shedding white sparks." Remarkably, the first fireball was followed by a second. "Nearly 7 or 8 min later another was sighted directly over Amarillo moving the same direction," adds Byrd.

US Space Command reports no satellites or pieces of space junk decaying at the time of the sightings. This was probably a random meteoroid--and maybe two--disintegrating in Earth's atmosphere.

SOUTHWESTERN FIREBALL: Last night (Sept. 21st) around 09:01 pm MDT, a dazzling fireball glided across the skies of New Mexico and west Texas. "We’ve been getting a lot of calls in the newsroom about an object – maybe a meteorite – falling from the sky," says Peter St. Cyr of KOAT TV in Albuquerque. An all-sky camera outside Santa Fe caught the object in flight. Click on the image to launch a 5 MB movie:  Note: In the movie, the stationary light is the full Moon, the moving light is the fireball.

If Jupiter is up at midnight, it must be opposite the sun: diagram. Indeed, astronomers call this "Jupiter's night of opposition." The effect of opposition may be seen in the shadow of Jupiter's moon Io, shown here in a photo taken last night by Anthony Wesley of Australia:

"Io was almost on top of its own shadow," points out Wesley. "This is due to the near-perfect alignment of Jupiter, Earth and the sun."

In a coincidence of interplanetary proportions, Uranus is also at opposition tonight. This rare double opposition of two giant planets is a once-in-a-lifetime event. Unlike Jupiter, Uranus is barely visible to the naked eye, a result of its smaller size and greater distance. It looks great, however, through a small telescope. Just point your optics at Jupiter and you will find emerald Uranus about 1^o away.

more images: from Alan Friedman at the Mt. Wilson Observatory in California; from Pete Lawrence of Selsey, West Sussex, UK; from Efrain Morales Rivera of Aguadilla, Puerto Rico; from Sadegh Ghomizadeh of Iran Tehran; from Jerôme Grenier of Paris, France; from Frank Olsen of Tromvik, Norway; from Jimmy Eubanks of Boiling Springs, SC; from Mark Humpage of Lutterworth, UK; from P. Nikolakakos of Sparta, Greece;  

BIG SUNSPOT: One of the biggest sunspots of new Solar Cycle 24 is rotating around the sun's southeastern limb. Presenting ... active region 1108:

Rogerio Marcon took the picture yesterday from his backyard observatory in Campinas, Brasil. Although the sunspot is big---the primary core is twice as wide as Earth--it has not yet produced any significant eruptions, only a smattering of B-flares and one C-class event. The quiet may be temporary. The sunspot's magnetic field harbors energy for major activity. NOAA forecasters estimate a 25% chance of an M-flare during the next 24 hours.

more images: from John Stetson of Portland, Maine; from Peter Paice of Belfast, Northern Ireland; from John Nassr of Baguio, Philippines; from Jo Dahlmans of Ulestraten the Netherlands; from Cai-Uso Wohler of Bispingen, Germany; from Robert Arnold of Isle of Skye, Scotland; from Peter Desypris of Syros Greece; from James Kevin Ty of Manila , Philippines

EMERGING SUNSPOT: A new sunspot is emerging over the sun's southeastern limb, and its magnetic canopy is seething with activity. Click on the image to watch 90 minutes of action recorded during the late hours of Sept. 15th by NASA's Solar Dynamics Observatory:

Because the sunspot's dark core is visible only in profile, its characteristics are a matter of guesswork. NOAA forecasters say that "C-class events are likely." If so, the eruptions will blow into space over the sun's limb--a nice photo-op for readers with solar telescopes. Stay tuned for updates and better views as the sunspot turns toward Earth.

AURORA WATCH: There's a reason they call Alaska "aurora country." Last night near Fairbanks, for no particular reason, the sky turned green:

"It was a nice quiet display that lasted more than an hour," reports photographer Lance Parrish of Skiland. "I had plenty of time to record the show using my Nikon D3. A 10 second exposure at 1600 ISO worked very nicely."

Alaskans and other Northerners should take note of those settings, because tonight there is a reason for auroras. The sun's magnetic field is tipping south, opening a crack in Earth's magnetosphere. Solar wind pouring in could fuel a renewed display.

Planet Smells Funny

Sept. 13, 2010:  Giant planet GJ 436b in the constellation Leo is missing something.

Would you believe swamp gas?

To the surprise of astronomers who have been studying the Neptune-sized planet using NASA's Spitzer Space Telescope, GJ 436b has very little methane (CH₄).

"Methane should be abundant on a planet of this temperature and size, but we found 7000 times less methane than what the models predict," says Kevin Stevenson of the University of Central Florida (UCF). Stevenson was lead author of a paper reporting the result in the April 22, 2010, issue of Nature.

The methane deficit is surprising because in our own solar system all gas giants are methane-rich. Hydrogen and carbon are abundant in the atmospheres of Jupiter, Saturn, Uranus and Neptune. These atoms naturally get together to form the simplest hydrocarbon, CH₄.

The example of our local gas giants shaped expectations when Stevenson and colleagues pointed Spitzer in the direction of GJ 436b, only 33 light-years away. Finding methane was a foregone conclusion. But when the researchers analyzed the planet's spectrum, they found little of it. Instead, the atmosphere was rich in carbon monoxide.

"Actually, it blew our minds," says principal investigator and co-author Joseph Harrington, also of UCF.

Where did all the methane go? One possibility: it's being broken apart. "UV radiation from the planet's star could be converting the methane into polymers like ethylene," says Harrington. "If you put plastic wrap out in the sun, the UV radiation breaks down the carbon bonds in the plastic, causing it to deteriorate as the long carbon chains break. We propose a similar process on GJ 436b, but there hydrogen atoms split off from methane and let the remnants stick together to make ethylene (C₂H₄)."

Also, they speculate, strong vertical winds in the planet's atmosphere might be sweeping up material from deep hot layers where carbon monoxide is abundant. CO thus replaces CH₄.

Or it could be something else entirely.

"This planet's atmosphere could have some sort of alien chemistry going on," says Harrington. "We just don't know yet."

Giant planets aren't the only worlds with methane. CH₄ is fairly common on Earth, too. Methane forms in the stomachs of cows and goats. It also bubbles up from the bottom of swamps, a byproduct of organic matter decaying in deep mud. On gas giants, methane is just common chemistry, but on our planet, it is a sign of life.

For this reason, researchers have long planned to look for methane in the atmospheres of distant Earth-sized planets. NASA's Kepler mission is expected to discover many Earth-sized planets over the next few years, so the scientists will have plenty of promising targets to pursue. Methane floating alongside oxygen could be compelling evidence of biological activity.

But what if planetary atmospheres don't always follow the rules of our own Solar System? GJ 436b certainty doesn't. Investigators might have to go back to the drawing board and re-figure their chemistry.

"GJ 436b is telling us something important," says Harrington: "We’re not in Kansas anymore."

Authors: Dr. Tony Phillips, Dauna Coulter | Credit: Science@NASA

NEW ERUPTION--UPDATE: During the waning hours of Sept. 10th, a magnetic filament erupted in the sun's northern hemisphere: SDO movie. Newly-arriving data from the Solar and Heliospheric Observatory clearly show a CME emerging from the blast site: SOHO movie. Although the CME is not heading toward Earth, the outskirts of the expanding cloud could hit our planet's magnetic field during the late hours of Sept 12th or Sept. 13th. High-latitude sky watchers should be alert for auroras.

TRICKY CLOUD SHADOWS: Which is higher, the contrail or the fluffy clouds? Inspect the shadows, then scroll down for the answer:

Contrary to appearances, the contrail is higher. It must be, because its shadow falls down on the clouds below.

Joanna Fengler took the picture yesterday from Rewal, Poland. "I was walking at the seaside with my family when we noticed this nice shadow cutting acoss the sky. It was a nice holiday atmospheric observation and an opportunity to explain the phenomenon to my small daughter."

Contrail shadows can be very tricky. They often appear to be on the wrong side of the contrail, disobeying the basic rules of ray propagation. Atmospheric optics expert Les Cowley explains the phenomenon here. When you see a contrail in the sunlit sky, look for the shadow. Where you find it might surprise you.

LIMB EXPLOSION: On Sept. 4th around 1600 UT, a magnetic filament erupted and hurled a massive coronal mass ejection (CME) off the sun's northwestern limb. Click on the image to view a close-up movie of the blast from NASA's Solar Dynamics Observatory:

Another movie from the Solar and Heliospheric Observatory (SOHO) shows the CME billowing into space. The cloud is not heading toward Earth, and no geomagnetic storms are expected from this blast.

However, space weather could be in the offing for a different reason. A solar wind stream is heading for Earth and it could spark auroras when it arrives on Sept. 5th or 6th. NOAA forecasters estimate a 50% chance of geomagnetic activity at high latitudes. People in Alaska, Canada, Scandinavia and Antarctica should be alert for auroras in the nights ahead.