PLASMA PUFFS: A magnetic filament is snaking over the sun's northeastern limb, and it is filled with cool dark "puffs" of solar plasma. Pete Lawrence sends this picture from his backyard observatory in Selsey, UK:

Each puff is about the size of Earth, but much less dense; solar plasma consists mainly of gaseous hydrogen. If you could fit one in our atmosphere, it would float.

Despite the diaphanous nature of these plasma clouds, they can cause quite a stir if they fall to the stellar surface, producing an intense flash of radiation called a "Hyder flare." So far, however, the puffs seem to be held firmly aloft by the magnetic filament shown in this SDO image. No explosions are in the offing.

NEW SUNSPOT 1084: A new sunspot is rotating into view around the sun's southeastern limb. Rogerio Marcon sends this picture from his backyard observatory in Campinas, Brazil:

The sunspot's dark core is about the size of Earth, and it sits at the vertex of a massive swirl of hot gas. Extreme UV images from NASA's Solar Dynamiics Observatory reveal the million-degree whirlpool: click here. So far the sunspot has been relatively quiet, producing no flares of note, but this could change if the magnetic field becomes unstable. Readers with solar telescopes are encouraged to monitor developments.

more images: from John C McConnell of Maghaberry, Northern Ireland; from Howard Eskildsen of Ocala, Florida; from Peter Desypris of Island of Syros Greece; from Jan Timmermans of Valkenswaard, The Netherlands; from Britta Suhre of Rosenheim, Bavaria, Germany

The bright display of Southern Lights was sparked by a solar coronal mass ejection (CME), which hit Earth's magnetic field and sparked a G1-class geomagnetic storm. On the other end of the planet, the same storm produced bright Northern Lights over Wisconsin, Minnesota and parts of Canada. Both poles were ringed in light at the same time.

This isn't the first time astronauts have seen auroras underfoot. The shuttle has flown right through auroral curtains with no ill effects--other than time lost while the crew crowds around the window to stare.The ISS also turns out to be a wonderful platform for aurora watching.

Next up: A solar wind stream is due to hit Earth's magnetic field on June 26th, possibly sparking a new round of geomagnetic activity. Sky watchers above and below should be alert for auroras.

SUMMER SOLSTICE: Monday, June 21st, is the longest day of the year in the northern hemisphere. Northern summer begins at 11:28 UT (7:28 EDT) when the sun reaches its highest point on the celestial sphere; southern winter begins at precisely the same moment. No matter where you live, Happy Solstice!

FATHER'S DAY BLAST: Consider it a Father's Day gift ... from the sun. This morning around 1 a.m. UT, magnetic fields on the sun's eastern limb became unstable and erupted, producing one of the most spectacular explosions of the year. NASA's Solar Dynamics Observatory recorded the action:

Click to play a 1.6 MB mpeg movie

The explosion did not cause a solar flare (a flash of electromagnetic radiation) but it did hurl a massive cloud of magnetized plasma into space: SOHO movie. Because of the blast site's location on the eastern limb, the cloud will not hit Earth. There won't be any geomagnetic storms or auroras. Future eruptions, however, could have greater effect.

more sun-shots: from Alan Friedman of Buffalo, NY; from Les Marczi of Welland, Ontario, Canada; from Larry Alvarez of Flower Mound, Texas; from Michael Buxton of Ocean Beach, California; from Roger Williams of Kalamazoo, Michigan; from Robert Arnold of Isle of Skye, Scotland; from Cai-Uso Wohler of Bispingen, Germany; from Peter Desypris of Island of Syros Greece;

NASA's Solar Dynamics Observatory recorded the B4-category flare on June 17th. Each seemingly miniscule flash of light in the movie is a continent-sized blast dwarfing any explosion ever produced on Earth by many factors of ten.

Believe it or not, solar physicists do consider this small. On the Richter scale of solar flares, B-flares are near the bottom, producing little or no effect on Earth. The really fearsome explosions are X-flares, more than a thousand times stronger than anything sunspot 1081 is likely to produce. X-flares will become more common as Solar Max approaches in 2013. Until then, relax. It's "only" a B-flare.

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June 16, 2010:  Almost 40 years ago, NASA's Mariner 9 spacecraft relayed to Earth the first video images of Mars' northern polar ice cap, revealing a strange pattern of spiral swirls that has puzzled scientists ever since. Using new data from the Mars Reconnaissance Orbiter (MRO), researchers have finally uncovered the secrets of the troughs that snake through the ice cap like a spiraled maze.

A 1972-era TV image of Mars' north polar cap. [more]

Jack Holt of the University of Texas and his graduate student Isaac Smith used radar data from MRO's Shallow Subsurface Radar to crack the case. Examining the details of this new data set has laid open the ice cap's internal structure, revealing clues to the massive ice troughs' formation.

Apparently, the wind did it.

"Radar cross sections reveal layers of ice deposited throughout the ice cap's history," says Holt. "The size and shape of those layers indicate that wind has played a key role in creating and shaping the spiral troughs."

Not only does wind shape the spirals, but also it causes them to move. They rotate around the north pole, turning like an excruciatingly slow pinwheel, curiously enough, against the wind.

Smith explains the process: "Cold air from the top of the ice cap sweeps down the slope, gaining speed and picking up water vapor and ice particles along the way. As this wind blows across the trough and starts up the other slope (the cooler side, facing away from the sun), it slows and precipitates the ice it holds. All of this ice is deposited on this cool slope, building it up, so the trough actually grows and migrates, over time, against the wind."

Alan Howard of the University of Virginia first suggested the ice trough migration model based on Viking spacecraft data back in 1982. His theory, that wind erosion and sunlight shape and move the troughs, was never widely accepted, but the new data supports it. [larger image]

The Coriolis force generated by Mars' rotation twists the winds sweeping down from the ice cap.

"That explains the troughs' spiral design," says Smith.

Similar formations can be found in Antarctic regions of Earth, but without the spiral shape.

Icy megadunes in Antarctica do not spiral like the ice troughs of Mars. [more]

"You don't see spirals in Earth's Antarctic ice sheet because local topography there prevents the winds from being steered by the Coriolis force."

The radar data have solved another icy mystery, too--the origin of Chasma Boreale.

Chasma Boreale is a Grand Canyon-sized chasm that slashes through the midst of the spiraled troughs. Theories to date suggested that either wind erosion or a single melt event excavated Chasma Boreale within the past 5 to 10 million years.

"Not so," says Holt. "The MRO data clearly show the chasm formed [long before the spirals did] in a much older ice sheet dating back billions of years. Due to the shape of that ancient sheet, the chasm grew deeper as newer ice deposits built up around it. Winds sweeping across the ice cap likely prevented new ice from building up inside the chasm [so it never filled up]."

The radar data also revealed a second chasm matching Boreale in size.

Chasma Boreale is indicated by an arrow in this modern image of the Martian north pole. [more]

"This chasm's never been seen before -- unlike Boreale, it did fill up with ice, probably because it's in a different location. Boreale is closer to the highest points of the ancient ice cap, where the winds are stronger and more consistent."

By discovering that both Chasma Boreale and the ice troughs were shaped by similar processes over different timescales, Holt and Smith answer some questions about Martian climate history. But they're also sparking new ones.

"For a long stretch of Martian history the ice layers were regular and uniform, then there was a distinct period when the spiral ice troughs got started," says Smith. "Something changed. There must have been a very fast (relatively speaking) and powerful change in climate. We still don't know what that change was."

"To figure that out, we need to look at the rest of Mars for evidence of other changes at that same time," says Holt. "This is just the tip of the ice berg."

NEW SUNSPOT: Magnetic fields are coalescing in the sun's northeastern quadrant to form a new sunspot. The growing active region is crackling with B-class flares, as shown in this movie from NASA's Solar Dynamics Obervatory.

HUBBLE FINDS NO DEBRIS: Even the Hubble Space Telescope cannot find any debris where an unknown object apparently hit Jupiter on June 3rd. Today, researchers released new HST images of the impact site, which show nothing but uninterrupted clouds. The non-detection is consistent with a relatively small asteroid or comet fragment making a shallow impact in Jupiter's high atmosphere. [more]

DEPARTING SUNSPOT: Sunspot 1081, the source of several picturesque solar flares over the weekend, is exiting stage right. The active region is rotating over the sun's western limb where it will soon be completely invisible from Earth. NASA's Solar Dynamics Observatory captured this parting shot:

The active region's dramatic profile is highlighted by loops of unstable magnetism filled with surging, hot solar plasma. Black space beyond the edge of the sun provides a velvety backdrop for what could be some lively action in the hours ahead. Readers with solar telescopes, catch it before it goes!

more images: from Robert Arnold of Isle of Skye, Scotland; from P-M Hedén of Vallentuna, Sweden; from Stephen Ames of Hodgenville, KY; from Gianfranco Meregalli of Milano Italy;

AURORAS AT THE SOUTH POLE: On June 10th, a solar wind gust hit Earth's magnetic field, causing the skies over Antarctica to turn green. Research scientist J. Dana Hrubes snapped this picture of a backlit weather station at the Amundsen-Scott South Pole Station:

The temperature reading? "-90 degrees F," says Hrubes. "It was cold," he allows, "but the skies were crystal clear and the auroras were very bright. It was a great time to be outside."

June 16th or 17th could be another great time. That's when a solar wind stream is due to hit Earth, possibly sparking a new round of high-latitude geomagnetic storms. Stay tuned for more scenes from the South Pole.

SOLAR ACTIVITY: The circumference of the sun is crowded with prominences today, several of which have erupted in spectacular fashion: SOHO images. These massive events are wonderful targets for backyard solar telescopes. Pete Lawrence sends this example from his private observatory in Selsey UK:

"June 14th is obviously prom day!" says Lawrence. "This impressive southeastern prominence looks like a wall of flame reaching out into space. If you have a solar telescope, try and get a look because it's still developing," he urges.

more images: from Robert Arnold of Isle of Skye, Scotland; from P-M Hedén of Vallentuna, Sweden; from Stephen Ames of Hodgenville, KY; from Gianfranco Meregalli of Milano Italy;

SOLAR FLARE UPDATE: Sunspot 1079 near the sun's southwestern limb has joined this weekend's flare show (described below) with a series of its own M- and C-class eruptions. Click here for an SDO movie entitled "Blowing Bubbles."

SOLAR FLARES: Sunspot 1081 is crackling with C- and M-class solar flares. Here is a picturesque C6-category blast recorded yesterday, June 12th (0917 UT), by NASA's Solar Dynamics Observatory (SDO):

[still frame] [movies: 1.6 MB mpeg; 1.3 MB iPad; 0.6 MB iPhone]

An even stronger M2-class flare on June 12th (0055 UT) sparked a bright flash of extreme ultraviolet radiation, propelled a shock wave through the sun's atmosphere, and hurled a billion-ton coronal mass ejection (CME) into space. The CME is expected to miss Earth--so no auroras.

The M-flare also produced a Type II radio burst. "Although the sun was setting here in New Mexico, I was able to record the burst at 28 MHz and 24 MHz," says amateur radio astronomer Thomas Ashcraft. "Here is an audio file. The slow swoosh you just heard is radio noise from the sun!" Another radio astronomer, Dick Flagg of Hawaii, used a radio spectrograph at Windward Community College in Oahu to record the burst's dynamic spectrum.

Sunspot 1081 appears to be in a state of slight decay, but that has not stopped the flares. Indeed, the decay may be contributing to magnetic instabilities underlying these explosions. Readers with solar telescopes are encouraged to monitor developments.

more images: from Cai-Uso Wohler of Bispingen, Germany; from David Evans of Coleshill, North Warwickshire, UK; from Alan Friedman of downtown Buffalo, NY; from Pavol.Rapavy of Observatory Rimavska Sobota, Slovakia; from Michael Borman of Evansville, Indiana; from Guenter Kleinschuster of Feldbach, Styria, Austria

MYSTERY OF THE MISSING DEBRIS: On June 3rd, amateur astronomers were startled by a bright flash of light on Jupiter. It appeared to be an impact event--a comet or asteroid hitting the planet's cloudtops. Curiously, though, the strike left no obvious debris. Was it really an impact--or something else? Today's story from Science@NASA discusses the possibilities.

SOLAR FLARES: Today, June 12th at 0055 UT, new sunspot 1081 unleashed an impulsive M1-class solar flare. NASA's Solar Dynamics Observatory recorded the blast in high-resolution:

movie formats: 2 MB mpeg; 0.9 MB iPad; 0.6 MB iPhone

The explosion hurled a billion-ton coronal mass ejection (CME) off the sun's western limb; the cloud will probably not hit Earth. The explosion also produced a Type II radio burst. "Although the Sun was setting here in New Mexico, I was able to record the burst at 28 MHz and 24 MHz," says amateur radio astronomer Thomas Ashcraft. "Here is an audio file. The slow swoosh is radio noise from the sun!"

The M2-flare was followed at 0917 UT by an even more picturesque C6-flare. SDO recorded that one, too: movie, still frame. More flares seem likely as restless sunspot 1081 continues to grow. Readers with solar telescopes are encouraged to monitor developments.

MAGNETIC UNREST: The magnetic field of sunspot 1078 is in a state of considerable unrest. Explosive reconnection events are happening every few minutes, resulting in a staccato rat-a-tat of low-level solar flares. The following movie from NASA's Solar Dynamics Observatory gives a one-hour sampling of the action:

movies: 0.8 MB mpeg; 0.6 MB iPad; 0.4 MB iPhone

Eventually, this growing sunspot could unleash a truly significant flare. Our planet, however, is not in the line of fire. Sunspot 1078 is turning away from Earth and will soon disappear over the sun's western limb. Readers with solar telescopes are encouraged to catch it before it goes.

more images: from John C McConnell of Maghaberry Northern Ireland; from Peter Paice of Belfast, Northern Ireland; from Pavol Rapavy of Observatory Rimavska Sobota, Slovakia

WATCH OUT FOR THAT COMET: One wonders... Did the inhabitants of galaxy NGC 891 duck when Comet McNaught flew past the edge-on spiral on the morning of June 8th? Mike O'Connor and Tristan Dilapo took this picture of the cosmic close encounter from Colden, New York:

"The comet was only 10 degrees above the horizon," says O'Connor. "Nevertheless, we got a good picture using a 12-inch telescope and an SBIG ST9-E camera."

And, no, the denizens of that distant galaxy did not flinch, flee, duck or take notice in any way. NGC 891 is 30 million light years away, far removed from the willowy tail of Comet McNaught.

We Earthlings are having the true close encounter. Comet McNaught (C/2009 R1) is gliding through the inner solar system, due to approach our planet only 100 million miles away on June 15th and 16th. The approaching comet looks great in small telescopes, and may yet become a naked-eye object before the end of the month. Because this is Comet McNaught's first visit, predictions of future brightness are necessarily uncertain; amateur astronomers should be alert for the unexpected.

more images: from Kerry-Ann Lecky Hepburn of Grimsby, Ontario; from Gregg Ruppel of Ellisville, MO; from Michael Jäger of Turmkogel, Austria; from Scott Tucker of Tucson, Arizona; from Jeff Greenwald of Laramie, Wyoming; from Feys Filip at the Public observatory "Sasteria" in Crete; from Gary of Fort Davis, TX; from Baqir of Quetta, Pakistan

new comet cometh

Ben Sandilands

Will the celestial omen of the fall of tyrants strike again?

If Halley's Comet in February 1986 presaged the People Power Revolution that swept Ferdinand Marcos from office in the Philippines, will this sudden stranger from deep space take away Kevin Rudd, just as past comets have been associated with the assassinations of Julius Caesar, Abraham Lincoln, and the demise of other historic figures and assorted calamities including earthquakes, volcanic eruptions, and outbreaks of pestilence?

OK. Let's cut to the astronomy, not the nonsense of astrology.

Comet McNaught C/2009 R1 will ride higher and higher in the southern skies from July 2, after it reaches perihelion, its closest approach to the sun.

The designation C/2009 R1 is important here. Rob McNaught, the British born Australian comet catcher who works for NASA searching for killer asteroids on the telescope studded slopes of Siding Spring Mountain, has now found 54 comets.

His most famous, C/2006 P1 McNaught, became the Great Comet of 2007 and has been described as the most spectacular such apparition seen from earth since a sequence of great comets hung menacingly above the battle fields of the American Civil War.

This particular Comet McNaught currently hugs the NE pre dawn horizon as seen from about Yarralumla northwards in the constellation Perseus, a bit to the side of pink planet Mercury for the next few days, if you are able to pick that up from a vantage point devoid of foreground clutter.

However after the comet vanishes into the glare of the sunrise in the last weeks of this month it will reappear in July, brightness unknown, and progressively higher in our skies. So far it has increased in visual brightness from that of a faint to medium brightness star, which makes it above average in terms of how 'new' comets behave at this stage of an approach to the inner solar system.

It may grow a spectacular tail spreading out from a dazzlingly bright coma or head, as did 'the' Comet McNaught of 2007, or it may just hide its traceries of ionised gases and streamers of dust from all but those with telescopes.

There is no election day available when it will not shine, however brightly or dimly, over Australian skies, as it slips back into the interstellar darkness from which it currently cometh.

No one really knows how bright this particular Comet McNaught will become. (There is another Comet McNaught catalogued as C/2009 K5 in the high arctic skies at the moment, except that it is currently polar daytime up there, so there is no night in which to see it.)

Comet McNaught C/2009 R1 was found in the course of a serious space watch program that looks for earth crossing objects - comets or asteroids - that may be following trajectories or orbits that come sufficiently close to us to pose an immediate or longer term risk of collision.


Ben Sandilands is a freelance writer and broadcaster.

COMET McNAUGHT: A fresh comet is swinging through the inner solar system, and it is brightening rapidly as it approaches the sun. Presenting, Comet McNaught (C/2009 R1):

Michael Jäger of Stixendorf, Austria, took the picture on June 6th using an 8-inch telescope. The comet's green atmosphere is larger than the planet Jupiter, while the long willowy ion tail stretches more than a million kilometers through space. These dimensions make the comet a fine target for backyard telescopes.

Comet McNaught can be found low in the northeastern sky before dawn gliding through the constellation Perseus. It is brightening as it approaches Earth for a 1.13 AU close encounter on June 15th and 16th. Currently, the comet is at the threshold of naked eye visibility (5th to 6th magnitude) and could become as bright as the stars of the Big Dipper (2nd magnitude) before the end of the month. Because this is the comet's first visit to the inner solar system, predictions of future brightness are necessarily uncertain; amateur astronomers should be alert for the unexpected. [ephemeris] [3D orbit] [Sky & Telescope: sky map, full story]

more images: from John Chumack of Yellow Springs, Ohio; from Primoz Cigler of Bohor, Slovenia; from Pete Lawrence of Selsey, West Sussex, UK; from Feys Filip at the Public Observatory "Sasteria" in Crete; from Monika Landy-Gyebnar of Veszprem, Hungary; from Petr Horalek of Ustupky, Czech republic;

MEMORIAL DAY FIREWORKS: On May 31st, around 2100 UT, a magnetic filament erupted on the sun. NASA's Solar Dynamics Observatory (SDO) recorded the action with 10-times HDTV resolution. Click on the image to play the movie--and be alert for "the twist!"

Movie formats: 1 MB mpeg, 1.2 MB iPad, 0.5 MB iPhone

Magnetic filaments on the sun are a bit like rubber bands. They store energy when they are twisted. Take a rubber band from your desk and try it--twist, twist, twist. Eventually it will reach its fill and untwist explosively. That's more or less what happened on the sun. Play the movie again and note the untwisting motions near the center of the tempest. SDO's clear vision is revealing how these explosions work in unprecedented detail. Stay tuned for more.