September 29, 2009: Planning a trip to Mars? Take plenty of shielding. According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high.

"In 2009, cosmic ray intensities have increased 19% beyond anything we've seen in the past 50 years," says Richard Mewaldt of Caltech. "The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions."

Above: Energetic iron nuclei counted by the Cosmic Ray Isotope Spectrometer on NASA's ACE spacecraft reveal that cosmic ray levels have jumped 19% above the previous Space Age high. [larger image]

The cause of the surge is solar minimum, a deep lull in solar activity that began around 2007 and continues today. Researchers have long known that cosmic rays go up when solar activity goes down. Right now solar activity is as weak as it has been in modern times, setting the stage for what Mewaldt calls "a perfect storm of cosmic rays."

Galactic cosmic rays come from outside the solar system. They are subatomic particles--mainly protons but also some heavy nuclei--accelerated to almost light speed by distant supernova explosions. Cosmic rays cause "air showers" of secondary particles when they hit Earth's atmosphere; they pose a health hazard to astronauts; and a single cosmic ray can disable a satellite if it hits an unlucky integrated circuit.

The sun's magnetic field is our first line of defense against these highly-charged, energetic particles. The entire solar system from Mercury to Pluto and beyond is surrounded by a bubble of magnetism called "the heliosphere." It springs from the sun's inner magnetic dynamo and is inflated to gargantuan proportions by the solar wind. When a cosmic ray tries to enter the solar system, it must fight through the heliosphere's outer layers; and if it makes it inside, there is a thicket of magnetic fields waiting to scatter and deflect the intruder.

An artist's concept of the heliosphere, a magnetic bubble that partially protects the solar system from cosmic rays. [larger image]

"At times of low solar activity, this natural shielding is weakened, and more cosmic rays are able to reach the inner solar system," explains Pesnell.

Mewaldt lists three aspects of the current solar minimum that are combining to create the perfect storm:

1. The sun's magnetic field is weak. "There has been a sharp decline in the sun's interplanetary magnetic field down to 4 nT (nanoTesla) from typical values of 6 to 8 nT," he says. "This record-low interplanetary magnetic field undoubtedly contributes to the record-high cosmic ray fluxes." [data]

2. The solar wind is flagging. "Measurements by the Ulysses spacecraft show that solar wind pressure is at a 50-year low," he continues, "so the magnetic bubble that protects the solar system is not being inflated as much as usual." A smaller bubble gives cosmic rays a shorter-shot into the solar system. Once a cosmic ray enters the solar system, it must "swim upstream" against the solar wind. Solar wind speeds have dropped to very low levels in 2008 and 2009, making it easier than usual for a cosmic ray to proceed. [data]

3. The current sheet is flattening. Imagine the sun wearing a ballerina's skirt as wide as the entire solar system with an electrical current flowing along its wavy folds. It's real, and it's called the "heliospheric current sheet," a vast transition zone where the polarity of the sun's magnetic field changes from plus to minus. The current sheet is important because cosmic rays are guided by its folds. Lately, the current sheet has been flattening itself out, allowing cosmic rays more direct access to the inner solar system.

The heliospheric current sheet is shaped like a ballerina's skirt. Image credit: J. R. Jokipii and B. Thomas, Astrophysical Journal 243, 1115, 1981.

"If the flattening continues, we could see cosmic ray fluxes jump all the way to 30% above previous Space Age highs," predicts Mewaldt. [data]

Earth is in no great peril. Our planet's atmosphere and magnetic field provide some defense against the extra cosmic rays. Indeed, we've experienced much worse in the past. Hundreds of years ago, cosmic ray fluxes were at least 200% to 300% higher than anything measured during the Space Age. Researchers know this because when cosmic rays hit the atmosphere, they produce an isotope of beryllium, ¹⁰Be, which is preserved in polar ice. By examining ice cores, it is possible to estimate cosmic ray fluxes more than a thousand years into the past. Even with the recent surge, cosmic rays today are much weaker than they have been at times in the past millennium. [data]

"The space era has so far experienced a time of relatively low cosmic ray activity," says Mewaldt. "We may now be returning to levels typical of past centuries."

NASA spacecraft will continue to monitor the situation as solar minimum unfolds. Stay tuned for updates.

Author: Dr. Tony Phillips | Credit: Science@NASA

Mercury's magnetic field is buffeted by solar wind as much as fifteen times stronger than the solar wind we experience at Earth. During an earlier flyby of Mercury in Oct. 2008, MESSENGER encountered magnetic "tornadoes" – twisted bundles of magnetic fields connecting Mercury to interplanetary space. The twisters are formed by explosive magnetic reconnection events at the solar wind-magnetic field boundary. Solar wind can actually flow down the throats of these tornadoes to strike and erode the surface of Mercury, giving Mercury a comet-like tail.

MESSENGER will fly right through this maelstrom of magnetism and solar wind en route to buzzing Mercury's surface. Stay tuned for data!

This weekend, comes NEAR the comet

Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

(In case you're still looking, the comet is here.)

"This is by far the biggest prominence I've seen since I got my Personal Solar Telescope in 2005," he says. "I hope this is a taste of things to come as we start climbing out of solar minimum."

more images: from Emiel Veldhuis of Zwolle, the Netherlands; from Francisco A. Rodriguez of Cabreja Mountain Observatory, Canary Islands; from Pete Lawrence of Selsey, West Sussex, UK; from Cai-Uso Wohler of Bispingen, Germany; from P-M Hedén of Ålbo, Sweden; from Fabio Mariuzza of Biauzzo, Italy; from Rich Schueller of Massachusetts;

September 24, 2009: Meteorites recently striking Mars have exposed deposits of frozen water not far below the Martian surface. Pictures of the impact sites taken by NASA's Mars Reconnaissance Orbiter show that frozen water may be available to explorers of the Red Planet at lower latitudes than previously thought.

"This ice is a relic of a more humid climate from perhaps just several thousand years ago," says Shane Byrne of the University of Arizona, Tucson.

Byrne is a member of the team operating the orbiter's High Resolution Imaging Science Experiment, or HiRISE camera, which captured the unprecedented images. Byrne and 17 co-authors report the findings in the Sept. 25 edition of the journal Science.

Above: A fresh, 6-meter-wide, 1.33-meter-deep crater on Mars photographed on Oct. 18, 2008, and again on Jan. 14, 2009, by Mars Reconnaissance Orbiter's HiRISE camera. The bright material is ice, which fades from Oct. to Jan. because of sublimation and obscuration by settling dust. [more]

"We now know we can use new impact sites as places to look for ice in the shallow subsurface," adds Megan Kennedy of Malin Space Science Systems in San Diego, a co-author of the paper and member of the team operating the orbiter's Context Camera.

The finds indicate water-ice occurs beneath Mars' surface halfway between the north pole and the equator, a lower latitude than expected in the dry Martian climate.

During a typical week, the spacecraft's Context Camera returns more than 200 images of Mars that cover a total area greater than California. The camera team examines each image, sometimes finding dark spots that fresh, small craters make in terrain covered with dust. Checking earlier photos of the same areas can confirm a feature is new. In this way, the team has found more than 100 fresh impact sites.

An image from the camera on Aug. 10, 2008, showed apparent cratering that occurred after an image of the same ground was taken 67 days earlier. The opportunity to study such a fresh impact site prompted a look by the orbiter's higher resolution camera on Sept. 12, 2009, confirming a cluster of small craters.

Right: The patch of ice exposed at this late-2008 crater was large enough for the orbiter's spectrometers to take readings and confirm that it is H₂O. [more]

"Something unusual jumped out," Byrne said. "We observed bright material at the bottoms of the craters with a very distinct color. It looked a lot like ice."

The bright material at that site did not cover enough area for a spectrometer instrument on the orbiter to determine its composition. "Was it really ice?" the team wondered. The answer came from another crater with a much larger area of bright material.

"We were excited [when we saw it], so we did a quick-turnaround observation," said co-author Kim Seelos of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Everyone thought it was water-ice, but it was important to get the spectrum for confirmation."

Mars Reconnaissance Orbiter Project Scientist Rich Zurek, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., said, "This mission is designed to facilitate coordination and quick response by the science teams. That makes it possible to detect and understand rapidly changing features."

Above: This map shows five locations where fresh impact cratering has excavated water ice from just beneath the surface of Mars (sites 1 through 5) and the Viking Lander 2 landing site (VL2), in the context of color coding to indicate estimated depth to ice. [more]

The ice exposed by fresh impacts suggests that NASA's Viking Lander 2, digging into mid-latitude Mars in 1976, might have struck ice if it had dug only 10 centimeters (4 inches) deeper. The Viking 2 mission, which consisted of an orbiter and a lander, launched in September 1975 and became one of the first two space probes to land successfully on the Martian surface. The Viking 1 and 2 landers characterized the structure and composition of the atmosphere and surface. They also conducted on-the-spot biological tests for life on another planet.

To view images of the craters and learn more about the Mars Reconnaissance Orbiter visit http://www.nasa.gov/mro.

Editor: Dr. Tony Phillips | Credit: Science@NASA

http://www.nasa.gov/mission_pages/MRO/news/mro20090924.html

If you thought that flare seemed small, you were right. It was about 100-times too weak too affect Earth. During Solar Maximum, such a minor eruption would probably go unnoticed and certainly unmentioned. But during the deepest solar minimum in almost 100 years, it's a big event. A C-flare! The blast raised no radio blackouts or radiation storms--only the hopes of solar observers for something more flamboyant. Stay tuned.

sunspot photos: from Pete Lawrence of Selsey, West Sussex, UK; from Andy Yeung of Hong Kong; from John C McConnell of Maghaberry Northern Ireland.; from Trevor Little on the south coast of England; from Francisco A. Rodriguez of Cabreja Mountain Observatory, Canary Islands; from Richard Best of Sussex, England; from Fabio Mariuzza of Biauzzo, Italy; from Jörgen Blom of Stockholm, Sweden; from Pavol Rapavy of Observatory Rimavska Sobota, Slovakia

Lieida professor spots large asteroid over 1 kilometre in diameter, 645,000 miles from Earth.

After six days of monitoring by the Minor Planet Centre at the University of Harvard, it has been termed, asteroid 2009 ST19.

Lieida professor spots large asteroid over 1 kilometre in diameter, 645,000 miles from Earth.

Professor Josep Maria Bosc from the Field Learning Observation Centre of the Universe, discovered the asteroid on September 16 from his observatory, on Montmagastrell Santa Maria (Lleida) , which in real terms means the asteroid came the closest to Earth than any other in the past.

After six days of monitoring by the Minor Planet Centre at the University of Harvard, it has been termed, asteroid 2009 ST19. This is classed as an Apollo, a potentially dangerous kind to the planet because its orbit overlaps with that of Earth. The asteroid is also the largest, at more than a kilometre in diameter, that has come close to Earth. At the time of its closest approach it passed 645,000 miles abve the Earth.

The last similar incident dates back to 1937, when the asteroid Hermes passed 750,000 miles over the Earth.

 

"Moreover," he adds, "a second sunspot has appeared, number 1027, and it is growing rapidly."

Two big sunspots in one day? That hasn't happened in more than a year. Two is not enough to end the deepest solar minimum in a century; nevertheless, it is a welcome interruption. Readers with solar telescopes are encouraged to monitor developments.

more images: from Chin Wei Loon of As-syams Solar Observatory, University of Malaya, Malaysia; from Adrian Guzman of San Jose, California; from Guenter Kleinschuster of Feldbach, Austria; from Vahan Yeterian of Lompoc, California; from John C McConnell of Maghaberry Northern Ireland; from Francisco A. Rodriguez of Cabreja Mountain Observatory, Canary Islands; from Peter Paice of Belfast, Northern Ireland;

SUNSPOT 1026: One sunspot is not enough to end the deepest solar minimum in nearly a century, but you've got to start somewhere. "Finally, a new sunspot!" says Paul Maxson who sends this picture from his observatory in Surprise, Arizona:

Sunspot 1026 emerged yesterday to break a string of 19 consecutive spotless days. It's about as wide as Earth, which makes it an easy target for backyard solar telescopes. The Solar and Heliospheric Observatory (SOHO) has measured the spot's magnetic polarity and identified it as a member of new Solar Cycle 24. Could this be a harbinger of more to come? (Apparently so.) Stay tuned.

more images: from Pete Lawrence of Selsey, West Sussex, UK; from Michał Nyklewicz of Poland; from Athanasios Georgiou of Filyro, Greece; from Jan Koeman of Kloetinge, The Netherlands; from Peter Paice of Belfast, Northern Ireland; from Emiel Veldhuis of Zwolle, the Netherlands; from Alan Friedman of Buffalo, NY; from Eva Vidovic of Stojnci, Slovenia; from A.Cote, W. Frame and John Stetson of South Portland, Maine.

Current conditions

Today is the equinox, but the sun came up directly east yesterday, so the sun is still off schedule from the norm.

The high southern latitude of the spot identifies it as a member of new Solar Cycle 24. We'll get a better view later today as the sun's rotation turns the active region more squarely toward Earth. Readers with solar telescopes are encouraged to monitor developments.

more images: from Emiel Veldhuis of Zwolle, the Netherlands; from Alan Friedman of Buffalo, NY; from Eva Vidovic of Stojnci, Slovenia; from A.Cote, W. Frame and John Stetson of South Portland, Maine; from CJ Wood of Ridgely, Maryland

Current conditions

Jupiter Turned Comet Into "Moon" for 12 Years

James Owen
for National Geographic News
 

September 21, 2009

ago, Jupiter carried on a 12-year fling with an extra "moon" then casually cast it aside—and the gas giant will likely do it again within decades, scientists announced today.

In 1949 the massive planet's gravity pulled in comet 147P/Kushida-Muramatsu and held it in orbit until 1961, according to an international team led by Katsuhito Ohtsuka of the Tokyo Meteor Network.

Enlarge

RELATED

• NEW JUPITER IMAGE: Sharpest View Ever From Earth
• Photo Gallery: Jupiter
• PHOTO IN THE NEWS: Jupiter Gains New Red Spot

The 1,300-foot-wide (400-meter-wide) comet's stint as a so-called temporary satellite was revealed when the researchers used calculations taken since the comet's 1993 discovery to determine the space rock's past course.

"We can be fairly sure that the comet orbited Jupiter once or twice before escaping it," said team member David Asher of the U.K.'s Armagh Observatory.

Temporary "Moon" Ended With a Bang

Only one temporary satellite has been observed falling prey to a planet's pull: comet Shoemaker-Levy 9, which broke apart and crashed into Jupiter in 1994. (See a Hubble Space Telescope picture of comet debris approaching Jupiter.)

A mysterious debris plume spotted on Jupiter this past July may have been caused by the spectacular impact of another such temporary satellite, Asher said.

Unlike those objects, comet Kushida-Muramatsu eventually escaped Jupiter's gravity. It currently circles the sun in the solar system's asteroid belt, between the orbits of Mars and Jupiter.

Before long, though, another comet is destined for moondom. Between 2068 and 2086, comet 111P/Helin-Roman-Crockett is expected to be captured and complete six laps around Jupiter, the astronomers say.

Earth Unlikely to Gain Extra Moon

It's doubtful that our own planet would have the gravitational pulling power to add a temporary satellite to the night sky, Asher said.

"There are examples of small objects that the Earth had captured and then escaped again, so it could in principal happen," Asher said.

"But with one of these larger objects—objects big enough to cause serious damage, were they to impact the Earth—fortunately they are much more likely to be captured by Jupiter"—sparing Earth a potential Armageddon.

Findings presented today at the European Planetary Science Congress in Potsdam, Germany.

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SOURCES AND RELATED WEB SITES

• Armagh Observatory
• European Planetary Science Congress 2009

The tangle of hot, magnetized plasma circled above almost certainly overlies a large new-cycle sunspot. We'll soon find out. The sun's rotation is turning the active region toward Earth and it could pop over the sun's eastern limb as early as Sept. 21st. Readers with solar telescopes are encouraged to monitor developments.

"It was an impressive display," says Blackwell. "To the naked eye, it was visible for about a minute."

It looks like a passing comet or a giant, luminous amoeba. But this was pure rocket science. The cloud was created by a Black Brant XII sounding rocket launched from NASA's Wallops Flight Facility in Virginia. The rocket released a cloud of electrically-charged aerosols near the top of Earth's atmosphere to investigate the formation of noctilucent clouds or "NLCs." Mysterious NLCs form naturally around Earth's poles during the months of northern summer. On this September evening, researchers decided to see if they could create an artificial NLC at mid-latitudes; it seems to have worked.

Ground-based cameras and radars along the Atlantic coast monitored the experiment while the STPSat-1 satellite watched from Earth orbit. Principal investigators at the Naval Research Lab hope the data will reveal much about the microphysics of noctilucent clouds and the possible role of rockets in creating them.

more images: from Neil Winston of Lusby, Maryland; from Geoff Chester of Alexandria, Virginia; from Greg Piepol near Manassas, Virginia; from Tom McIntyre of Central Park, New York;

Graphic by Cindy O'Dell, Orange County Register

Juno was discovered by astronomer Karl L. Harding on Sept.1, 1804.

You’ll need a small telescope and a bit of patience. But now through early next week, you should be able to spot asteroid Juno streaking through the cosmos, high above the southeast horizon, says NASA. We suggest that you look for Juno shortly before midnight, roughly 50 degrees above the southeast. (Hold your arm out straight. Make the bottom of your fist even with the horizon. A fist is about 10 degrees tall, astronomically speaking.)

Juno, which is about 145 miles in diameter, will reach its maximum brightness on Monday night. But astronomers say you can see it now, and its worth taking a look.  From our perspective, this is the brightest Juno will be until 2018. And you’ll be seeing a stony mass that astronomers say may represent about 1 percent of the entire mass in the asteroid belt. You’ll also be looking at something of an optical illusion. Juno will appear like it is not moving. But the asteroid is actually traveling about 49,000 mph, on a path that’s about 112 million miles from Earth. It also rotates once every 7 hours and 21 minutes.

Courtesy of Harvard-Smithsonian Center for Astrophysics. (NM stands for nanometers. The asteroid was photographed from the Mt. Wilson Observatory in varying wavelengths.)

Earlier on Sciencedude:

Photo credit: STEREO-B Extreme UV Telescope

Irene Gonzalez-Hernandez, a solar physicist working on the GONG project, says "I believe this is a large active region belonging to new Solar Cycle 24. The sun's rotation should turn it toward Earth for direct viewing on Sept. 20th."

Until then, the sunspot number remains pegged at zero. Why? Because farside sunspots do not count. Back in the 19th century when the sunspot number was invented, astronomers had no way of monitoring events on the farside of the sun, so no provision was made for adding farside spots to the total. Fast forward to 2009: NASA has two spacecraft (STEREO-A and -B) maneuvering for a 360^o view of the entire sun, and by the year 2011 no sunspot will escape their detection. A more modern way of counting sunspots may soon be required.

The prominence has been growing for more than a day. As it towers higher and higher above the surface of the sun, the odds increase that it will erupt and come crashing down--a must-see. Readers, if you have a solar telescope, train your optics on the sun's southeastern limb.

more images: from J. Macieszek and J. Stetson of South Portland, Maine

Yellowknife on Sept. 12th," writes Yuichi Takasaka from the Northwest Territories of Canada. "Northern Lights started to appear from 10pm local time and stayed well after 4am!"

SOLAR PROMINENCE WITH EARTH BEYOND?
WHERE WAS THE CAMERA?

09.11.2009

Sept. 11, 2009: NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) is racing toward a double-impact on the moon at 7:30 am EDT on Oct. 9th. Today NASA announced exactly where the crash will take place.

The target crater is Cabeus A. It was selected after an extensive review of the best places to excavate frozen water at the lunar south pole.

Above: Craters of interest around the lunar south pole. LCROSS is targeting Cabeus A. Image credit: NMSU/MSFC Tortugas Observatory.

"The selection of Cabeus A was a result of a vigorous debate within the lunar science community. We reviewed the latest data from Earth-based observatories and our fellow lunar missions Kaguya, Chandrayaan-1, and the Lunar Reconnaissance Orbiter," says Anthony Colaprete, LCROSS project scientist and principle investigator at NASA's Ames Research Center. "The team is looking forward to wealth of information this unique mission will produce."

LCROSS will search for ice by plunging its spent upper-stage Centaur rocket into the permanent shadows of Cabeus A, where water might be trapped in frozen form. The LCROSS satellite will then fly into the plume of debris kicked up by the impact and measure the properties of the plume before it also collides with the lunar surface.

Professional astronomers will use many of Earth's most capable observatories to monitor the impacts. These observatories include the Infrared Telescope Facility and Keck telescope in Hawaii; the Magdalena Ridge and Apache Ridge Observatories in New Mexico and the MMT Observatory in Arizona; the newly refurbished Hubble Space Telescope; and the Lunar Reconnaissance Orbiter, among others.

Amateur astronomers can monitor the impact, too. Observing tips may be found here.

"Telescopes participating in the LCROSS Observation Campaign will provide observations from different vantage points using different types of measurement techniques," says Jennifer Heldmann, lead for the LCROSS Observation Campaign at Ames. "These multiple observations will complement the LCROSS spacecraft data to help determine whether or not water ice exists in Cabeus A."

During a media briefing Sept. 11, Daniel Andrews, LCROSS project manager at Ames, provided a mission status update: The spacecraft is healthy and has enough fuel to successfully accomplish all mission objectives. Andrews also announced the dedication of the LCROSS mission to the memory of legendary news anchor, Walter Cronkite, who provided coverage of NASA's missions from the beginning of America's manned space program to the age of the space shuttle.

Right: The LCROSS mission has been dedicated to the memory of Walter Cronkite, who covered NASA missions from Mercury through the space shuttle. Image credit: CBS News. [more]

"Dad would sure be proud to be part, if just in name, of getting humans back up to the moon and beyond," says Chip Cronkite, son of the famed news anchor.

"We're looking forward to October 9th," Andrews says. "The next 28 days will undoubtedly be very exciting."

Cabeus A, here we come!

THE SHUTTLE APPEARS AS A COMET WHILE VENTING

INNER SPACE TERRANAUTS: This week, while astronauts orbited high above Earth installing new science equipment in the laboratories of the International Space Station, a team of terranauts descended into the Earth on their own mission of discovery. "We were not in outer space, but inner space," says explorer George Kourounis, who sends this picture from the Cave of Crystals in Naica, Mexico:

September 9, 2009: Astronomers have declared NASA's Hubble Space Telescope a fully rejuvenated observatory with the release of observations from four of its six operating science instruments. Sen. Barbara Mikulski of Maryland unveiled the images today at NASA Headquarters in Washington, DC.

"This marks a new beginning for Hubble," said Ed Weiler, associate administrator for NASA's Science Mission Directorate. "The telescope was given an extreme makeover and now is significantly more powerful than ever, well-equipped to last into the next decade."

Above: A selection of images from the rejuvenated Hubble: more.

View the complete gallery

Topping the list of new views are colorful, multi-wavelength pictures of far-flung galaxies, a densely packed star cluster, an eerie "pillar of creation," and a "butterfly" nebula. Hubble's suite of new instruments allows it to study the universe across a wide swath of the light spectrum, from ultraviolet all the way to near-infrared. In addition, scientists released spectroscopic observations that slice across billions of light-years to probe the cosmic-web structure of the universe and map the distribution of elements that are fundamental to life as we know it.

"I want to salute Team Hubble -- everyone who worked on Hubble from the Goddard Space Flight Center and Space Telescope Science Institute scientists in Maryland, to the ground crew at the Kennedy Space Center, to the Johnson Space Center where the astronauts train, and to the astronauts who were heroes in space," she concluded.

The new instruments are more sensitive to light and, therefore, will improve Hubble's observing efficiency significantly. It is able to complete observations in a fraction of the time that was needed with prior generations of Hubble instruments. The space observatory today is significantly more powerful than it ever has been.

Above: A sample spectrum obtained by Hubble's new Cosmic Origins Spectrograph (COS). More examples of COS data may be found here and here.

The new results are compelling evidence of the success of the STS-125 servicing mission in May, which has brought the space observatory to the apex of its scientific performance. Two new instruments, the Wide Field Camera 3 and Cosmic Origins Spectrograph, were installed, and two others, the Advanced Camera for Surveys and Space Telescope Imaging Spectrograph, were repaired at the circuit board level. Mission scientists also announced that the Near Infrared Camera and Multi-Object Spectrometer have been brought back into operation during three months of calibration and testing.

Right: Hubble's newly repaired Space Telescope Imaging Spectrograph (STIS) has revealed a stream of charged particles emerging from doomed star Eta Carina. [more]

"On this mission we wanted to replenish the 'tool kit' of Hubble instruments on which scientists around the world rely to carry out their cutting-edge research," said David Leckrone, senior project scientist for Hubble at NASA's Goddard Space Flight Center in Greenbelt, Md. "Prior to this servicing mission, we had only three unique instrument channels still working, and today we have 13. I'm very proud to be able to say, 'mission accomplished.' "

Hubble now enters a phase of full science observations. The demand for observing time will be intense. Observations will range from studying the population of Kuiper Belt objects at the fringe of our solar system to surveying the birth of planets around other stars and probing the composition and structure of extrasolar planet atmospheres. There are ambitious plans to take the deepest-ever near-infrared portrait of the universe to reveal never-before-seen infant galaxies that existed when the universe was less than 500 million years old. Other planned observations will attempt to shed light on the behavior of dark energy, a repulsive force that is pushing the universe apart at an ever-faster rate.

Hubble is back and better than ever. Let the observing begin!

For images and more information about the Hubble Space Telescope, visit http://www.nasa.gov/hubble

"The light of the Moon was refracted by Earth's atmosphere so that the Moon's image bent around the curvature of the earth. This caused it to appear earlier than expected," explains Stetson. Refraction also gave the Moon its distorted shape, a red fringe along the bottom and a green fringe on top. Stetson documented the full extent of the Moon's "playful illusions" in this sequence of photos.

Readers, check the US Naval Observatory's web site to find moonrise times for your hometown--and start watching early!

EXTRA: A more detailed discussion of Stetson's photo by atmospheric optics expert Les Cowley may be found here.

"I've never seen a fast ejection like this before," says Godard. "I recorded the action using a 3-inch refracting telescope and a Coronado SolarMax filter."

The blob does not appear to have escaped the sun. Indeed, it might not have been a blob at all, but rather a plasma wave traveling up a magnetic flux tube--and 'breaking' when it reached the top. Whether it was a rocketing blob or breaking wave, it shows that even the quiet sun is worth watching. Monitoring is encouraged.

more images: from Alan Friedman of Buffalo, New York; from Cai-Uso Wohler of Bispingen, Germany; from Francisco A. Rodriguez of Cabreja Mountain Observatory, Canary Islands; from Jimmy Eubanks of Boiling Springs, South Carolina; from Pavol Rapavy of Observatory Rimavska Sobota, Slovakia;

Volcanic aerosols are a source of cooling; ENSO and greenhouse gases cause heating; the solar cycle can go either way. When added together, these factors can account for 76% of the variance in Earth's surface temperature over the past ~30 years, according to the analysis of Lean and Rind.

Several aspects of their model attract attention: "The warmest year on record, 1998, coincides with the 'super-El Nino' of 1997-98," points out Lean. "The ESNO is capable of producing significant spikes in the temperature record." Solar minimum has the opposite effect: "A 0.1% decrease in the sun's irradiance has counteracted some of the warming action of greenhouse gases from 2002 - 2008," she notes. "This is the reason for the well-known 'flat' temperature trend of recent years."

What's next? Ultimately, the authors say, temperatures will begin rising again as greenhouse gases accumulate and solar activity resumes with the coming of the next solar cycle. Of couse, the solar cycle could be out of whack; if solar minimum deepens and persists, no one is certain what will happen. Lean and Rind reveal their predictions for the future here.

Reference: Lean, J. L., and D. H. Rind (2009), How will Earth's surface temperature change in future decades?, Geophys. Res. Lett., 36, L15708

September 3, 2009: The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?

"Personally, I'm betting that sunspots are coming back," says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, "there is some evidence that they won't."

Penn's colleague Bill Livingston of the NSO has been measuring the magnetic fields of sunspots for the past 17 years, and he has found a remarkable trend. Sunspot magnetism is on the decline:

Above: Sunspot magnetic fields measured by Livingston and Penn from 1992 - Feb. 2009 using an infrared Zeeman splitting technique. [more]

"Sunspot magnetic fields are dropping by about 50 gauss per year," says Penn. "If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015."

This disappearing act is possible because sunspots are made of magnetism. The "firmament" of a sunspot is not matter but rather a strong magnetic field that appears dark because it blocks the upflow of heat from the sun's interior. If Earth lost its magnetic field, the solid planet would remain intact, but if a sunspot loses its magnetism, it ceases to exist.

"This work has caused a sensation in the field of solar physics," comments NASA sunspot expert David Hathaway, who is not directly involved in the research. "It's controversial stuff."

The controversy is not about the data. "We know Livingston and Penn are excellent observers," says Hathaway. "The trend that they have discovered appears to be real." The part colleagues have trouble believing is the extrapolation. Hathaway notes that most of their data were taken after the maximum of Solar Cycle 23 (2000-2002) when sunspot activity naturally began to decline. "The drop in magnetic fields could be a normal aspect of the solar cycle and not a sign that sunspots are permanently vanishing."

Penn himself wonders about these points. "Our technique is relatively new and the data stretches back in time only 17 years. We could be observing a temporary downturn that will reverse itself."

The technique they're using was pioneered by Livingston at the McMath-Pierce solar  Livingston at the McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun's atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called "Zeeman splitting" after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism.

Right: Zeeman splitting of spectral lines from a strongly-magnetized sunspot. [more]

Astronomers have been measuring sunspot magnetic fields in this general way for nearly a century, but Livingston added a twist. While most researchers measure the splitting of spectral lines in the visible part of the sun's spectrum, Livingston decided to try an infra-red spectral line. Infrared lines are much more sensitive to the Zeeman effect and provide more accurate answers. Also, he dedicated himself to measuring a large number of sunspots—more than 900 between 1998 and 2005 alone. The combination of accuracy and numbers revealed the downturn.

If sunspots do go away, it wouldn't be the first time. In the 17th century, the sun plunged into a 70-year period of spotlessness known as the Maunder Minimum that still baffles scientists. The sunspot drought began in 1645 and lasted until 1715; during that time, some of the best astronomers in history (e.g., Cassini) monitored the sun and failed to count more than a few dozen sunspots per year, compared to the usual thousands.

"Whether [the current downturn] is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen," Livingston and Penn caution in a recent issue of EOS. "Other indications of solar activity suggest that sunspots must return in earnest within the next year."

Whatever happens, notes Hathaway, "the sun is behaving in an interesting way and I believe we're about to learn something new."

A solar wind stream flowing
from the indicated coronal hole
could reach Earth on Sept. 3rd or 4th.
Credit: SOHO Extreme UV Telescope

Hard to believe? It really happened--exactly 150 years ago. This map shows where auroras were sighted in the early hours of Sept. 2, 1859:

Above: Aurora sightings, Sept. 2, 1859. Image courtesy J.L. Green, NASA

As the day unfolded, the gathering storm electrified telegraph lines, shocking technicians and setting their telegraph papers on fire. The "Victorian Internet" was knocked offline. Magnetometers around the world recorded strong disturbances in the planetary magnetic field for more than a week.

The cause of all this was an extraordinary solar flare witnessed the day before by British astronomer Richard Carrington. His sighting marked the discovery of solar flares and foreshadowed a new field of study: space weather. According to the National Academy of Sciences, if a similar flare occurred today, it would cause $1 to 2 trillion in damage to society's high-tech infrastructure and require four to ten years for complete recovery.

A repeat of the Carrington Event seems unlikely from our low vantage in a deep solar minimum--but don't let the quiet fool you. Strong flares can occur even during weak solar cycles. Indeed, the Carrington flare itself occurred during a relatively weak cycle similar to the one expected to peak in 2012-2013. Could it happen again? Let's hope not.

August 2009 Aurora Gallery
[previous Augusts: 2008, 2007, 2006, 2005, 2004, 2003, 2002, 2001