Dee Finney's blog AUGUST SPACEWEATHER 2014

ARCTIC AURORAS: After a long, long summer day, Arctic skies are darkening again, and in the sunset observers are seeing rays of green in the twilight blue. Frank Olsen of Sortland, Norway, took this picture at sunset on Aug. 31st:

"I went out last night to catch the sunset--but mostly the auroras," says Olsen. "Even before it was dark, the Northern Lights made an appearance."

More lights are in the offing. NOAA forecasters estimate a 20% of polar geomagnetic storms during the next 24 hours. The odds of Arctic auroras are higher, however, because it doesn't take a full-fledged storm to turn the twilight green at polar latitudes. Now is a good time to book a tour. Aurora alerts: text, voice

MARS COMET PASSES STAR CLUSTER: Comet Siding Spring (C/2013 A1) is hurtling toward Mars for a near miss on Oct. 19, 2014. En route, a different near miss occured. On Aug. 28, the "Mars Comet" pass almost directly in front of globular star cluster NGC 362:

"I took the picture shortly after minimum separation between the two," says astrophotographer Damian Peach of Selsey, UK.

Less than two months from now the comet will reach Mars. Although the comet's nucleus will not strike the planet, gas and dust spewing out of the comet's core will likely interact with the Martian atmosphere. There could be a meteor shower, auroras, and other effects that no one can predict. NASA's fleet of Mars spacecraft and rovers will record whatever happens.

Amateur astronomers can monitor the comet's approach to Mars in the months ahead. Right now, Siding Spring is gliding through the southern constellation Tucana glowing about as brightly as a 11th magntitude star. Mid-sized telescopes such asthe Comet Hunter equipped with CCD cameras should have no trouble picking it up. [light curve] [ephemeris] [3D orbit]

COMET LANDING SITE SLIDESHOW: In mid-November, ESA's Rosetta spacecraft will make history by dropping a probe onto the surface of a comet. Bristling with 10 sensors including a camera, the Philae lander will touchdown somewhere on the rugged double-lobed core of comet 67P/Churyumov-Gerasimenko. But where? A new slideshow previews 5 candidate landing sites.

AURORAS EXPLODE THROUGH ARCTIC TWILIGHT: "After a long summer without stars, the Northern Lights have finally returned," reports Fredrik Broms of Tromsø, Norway (70 deg N latitude). "Last night's display was so strong that, although constellations such as Cassiopeia are still only to be made out very faintly on the blue night sky, the auroras shimmered and danced in an explosion of colors!" This is what he saw almost directly overhead around local midnight on August 28th:

GEOMAGNETIC ACTIVITY: Earth's magnetic field is still reverberating from a pair of CME strikes on August 27th. Although neither impact was particularly strong, the internal magnetic structure of the two solar storm clouds was just right for auroras. Last night, Alan Dyer photographed the display over the Grasslands National Park in Saskatchewan, Canada. Click to view a complete panorama:

"I shot this at the old pioneer Larson Ranch site in the Frenchman River valley just as the magnetic storm of Aug 27/28 hit its peak, covering much of the northern sky and lighting the ground and ranch buildings green," says Dyer. "The Larsons ran their ranch from the 1920s until 1985 when theirs became first land to be bought for the new Grasslands National Park. This is a stitch of 8 segments, each shot with the 15mm full-frame fish-eye lens at f/3.2 and Canon 6D at ISO 2500 for 1 minute each."

The CMEs that instigated the display were launched toward Earth on Aug. 22nd. As NOAA analysts predicted, the solar wind speed did not change much when the slow-moving CMEs arrived. However, the storm clouds were still effective because they contained a south-pointing magnetic field that opened a crack in Earth's magnetosphere. Solar wind poured in to fuel the show.

High-latitude sky watchers, if it is dark where you live, remain alert for auroras. Solar wind conditions continue to favor geomagnetic activity as August 28th unfolds.Aurora alerts: text, voice

GEOMAGNETIC ACTIVITY: Earth's magnetic field is unsettled today following the arrival of a CME during the early hours of August 27th. Around the North and South Poles, high-latitude sky watchers are reporting intermittently-bright auroras, like these photographed last night by Mike Theiss on the east coast of Iceland:

"The lights were incredible," says Theiss. "They changed intensity on and off for about 3 hours." Additional reports have come from New Zealand, Canada and northern-tier US states such as Maine, Michigan, Wisconsin, Idaho, North Dakota, and Washington: photo gallery.

The CME that instigated the display was launched toward Earth on Aug. 22nd. As NOAA analysts predicted, the solar wind speed did not change much when the slow-moving CME arrived. However, the storm cloud was still effective because it contained a south-pointing magnetic field that opened a crack in Earth's magnetosphere. Solar wind is poured in to fuel the show.

High-latitude sky watchers, if it is dark where you live, be alert for auroras. Solar wind conditions continue to favor geomagnetic activity as August 27th unfolds.Aurora alerts: text, voice

COMET CANDIDATE LANDING SITES SELECTED: Working over the weekend, Rosetta mission planners and scientists narrowed a list of 10 candidate landing sites to only 5. They are circled in this image of the core of 67P/Churyumov-Gerasimenko:

In mid-November, Rosetta's Philae lander will attempt to touch down in one of these locations--the first time humankind has ever landed a probe on the core of a comet.

The candidate sites are distributed as follows: three (I, B and J) on the comet's smaller lobe and two (A and C) on the larger. The comet's canyon-like neck has been excluded. All of the candidate landing sites provide at least six hours of daylight per comet rotation and offer some flat terrain. According to the ESA, every site has the potential for unique scientific discoveries by the lander's 10 instruments.

A full discussion of each site may be found in this ESA press release. By September 14th, the five candidates will have been assessed and ranked, leading to the selection of a primary landing site, for which a fully detailed strategy for the landing operations will be developed, along with a backup. Stay tuned for updates as the selection process unfolds.

MINOR STORM WARNING: A CME is heading for Earth. The relatively slow-moving storm cloud left the sun on Aug. 22nd and looks like it will take 4 days to cross the sun-Earth divide. NOAA forecasters estimate a 15% to 20% chance of polar geomagetic storms on Aug. 26-27 when the CME arrives. Aurora alerts: text,voice

M" FOR MAGNIFICENT: In the vocabulary of space weather, an "M-flare" is a medium-sized explosion. Yesterday it had a different meaning: magnificent. On August 24th at 12:17 UT, NASA's Solar Dynamics Observatory recorded this M5.6-category explosion near the eastern limb of the sun:

The source of the blast was sunspot AR2151. As the movie shows, an instability in the suspot's magnetic canopy hurled a dense plume of plasma into space. If that plasma cloud were to hit Earth, the likely result would be strong geomagnetic storms. However, because of the sunspot's location near the edge of the solar disk, Earth was not in the line of fire.

Even so, the flare did produce some Earth effects. A pulse of extreme UV radiation from the explosion partially ionized our planet's upper atmosphere, resulting in a Sudden Ionospheric Disturbance (SID). Waves of ionization altered the normal propagation of VLF (very low frequency) radio transmissions over the the dayside of Earth, an effect recorded at the Polarlightcenter in Lofoten, Norway: data.

Sunspot AR2151 will turn toward Earth in the days ahead, which means subsequent explosions could be more geoeffective. Follow the action @spaceweatherman

An explosion in the magnetic canopy of emerging sunspot AR2151 hurled a dense and twised plume of plasma into space. The Solar and Heliospheric Observatory (SOHO) recorded a bright coronal mass ejection emerging from the blast site:movie. If this CME were to ht Earth, the likely result would be strong geomagnetic storms. However, because of the sunspot's location near the sun's eastern horizon, Earth was not in the line of fire.

Nevertheless, the flare did produce some Earth effects. A pulse of extreme UV radiation partially ionized our planet's upper atmosphere. This "Sudden Ionospheric Disturbance" (SID) altered the normal propagation of VLF (very low frequency) radio transmissions over the the dayside of Earth, an effect recorded at the Polarlightcenter in Lofoten, Norway: data.

This sunspot will turn toward Earth in the days ahead, which means subsequent explosions could be more geoeffective. Stay tuned for updates. Solar flare alerts:text, voice

CELESTIAL TRIANGLE: The three brightest objects in the night sky, Venus, Jupiter and the Moon, converged this morning to form a bright triangle visible around the world. Kenneth Parsons sends this picture from Corpus Christi, Texas:

"I shot this at 6:10 AM on an absolutely clear morning with only a hint of breeze to mar the reflection of the Moon in the water," says Parsons.

Did you miss the show? Another "celestial triangle" is in the offing. This weekend the Moon will pass the sun en route to the evening sky. On August 31st it will join Mars and Saturn to form a new triangle in the constellation Libra. The new triangle won't be quite as luminous, because Mars and Saturn are not as bright as Venus and Jupiter, but the Moon-Mars-Saturn formation will be more compact and just as beautiful. Mark your calendar for the end of the month.

COMET LANDING SITE SELECTION: Europe's Rosetta probe has been at Comet 67P/Churyumov-Gerasimenko for two weeks, taking close-up pictures and making measurements of the comet's strange landscape. According to ESA, researchers now have the data they need to start picking a landing site. This weekend, mission planners will meet to consider 10 candidate locations, with the goal of narrowing the list to 5 by Monday. Stay tuned for results!

SOLAR ACTIVITY PICKS UP: A new sunspot emerging over the sun's NE limb is bringing an uptick in solar activity. AR2149 announced itself on August 21st with an impulsive M3-class solar flare. NASA's Solar Dynamics Observatory recorded the explosion's extreme ultraviolet flash:

UV radiation from the flare partially ionized the upper layers of Earth's atmosphere. This "Sudden Ionospheric Disturbance" altered the normal propagation of VLF (very low frequency) radio transmissions over the northern hemisphere, shown here in a recording from the Polarlightcenter in Lofoten, Norway. The disturbance has since subsided.

Because AR2149 is near the sun's eastern horizon, our view of the region is foreshortened. Evaluating the structure of its magnetic field is therefore tricky. As the sunspot turns toward Earth in the days ahead, we will get a better idea of its flare-producing potential. For now, NOAA forecasters are estimating a 25% chance of M-flares in the next 24 hours. Solar flare alerts: text, voice

WEAK IMPACT? MAGNIFICENT AURORAS: Visually, the CME that struck Earth's magnetic field on August 19th was dim and unimpressive. The auroras it produced were magnificent. "For the first time in my life, I saw the Northern Lights," says Tadas Janušonis who sends this photo from Vabalninkas, Lithuania:

"It is a very rare phenomenon here in Lithuania," he says, "but the August 19th impact was strong enough to [produce] them."

Actually, the impact was weak. A CME like this one hits with a mechanical pressure of no more than 1 or 2 nanoPascals. That's 1 or 2 billionths of a Pascal - softer than a baby's breath. The reason it was so effective had more to do with its inner magnetic structure. This CME contained a region of south-pointing magnetism that partially canceled Earth's north-pointing magnetic field, opening a crack in the magnetosphere. Solar wind poured and fueled the display.

The most famous photo of the storm, so far, was taken by astronaut Reid Wiseman onboard the International Space Station. "Never in my wildest dreams did I imagine this, " he tweeted. "Unbelievable." Yet many more photos prove that it really did happen! Aurora alerts: text, voice

GEOMAGNETIC STORM, AURORAS SEEN FROM SPACE: A moderate (G2-class) geomagnetic storm that erupted following a CME strike on August 19th issubsiding now. At its peak, the storm sparked auroras around both poles visible from the ground and from space. Astronaut Reid Wiseman took this picture from the window of the International Space Station:

"Never in my wildest dreams did I imagine this," tweeted Wiseman (@astro_reid). "Unbelievable."

Around the Arctic Circle where the midnight sun has overwhelmed auroras since Spring, observers caught their first glimpse of Northern Lights in months "At one point a massive corona unfolded just over my head!" reports Alexander Kuznetsov from the Finnish Lapland. "It was a great season opener," added Pekka Hyytinen of Tampere, Finland. "I also caught a lightning strike in one of my photos."

Solar wind conditions are unsettled but calming as Earth passes through the wake of the CME. NOAA forecasters estimate a waning 30% to 15% chance of more geomagnetic storms during the next 24 hours. Aurora alerts: text, voice

MORNING SHOW CONTINUES: Light pollution? No problem. The morning conjunction of Venus and Jupiter is bright enough to see through the worst urban glare. Jeff Dai sends this picture from metropolitan Chongqing, China:

"I woke up at 5 AM to enjoy this celestial dawn above the cityscape," says Dai. "It was gorgeous."

Dai took the picture on August 20th, two days after Venus and Jupiter were barely 0.2^o apart. Many observers have stopped looking now that the planets are separating, but as Dai's photo shows, they are still a beautiful pair. So set your alarm for dawn: the morning show continues. A date of special interest is August 23rd when the crescent Moon joins the planets to form a must-see celestial triangle.A video from NASA previews the meeting.

WEAK IMPACT: A CME hit Earth's magnetic field on August 19th at approximately 06:30 UT. The weak impact did not spark a strong geomagnetic storm nor any reports (so far) of visible auroras. NOAA forecasters say there is still a 30% chance of minor geomagnetic storms as Earth passes through the CME's wake. Update:Faint auroras have been reported over Alaska.

"It was a beautiful celestial dawn," says Nikodem, "definitely worth waking up for."

Following their 0.2^o near-miss on Monday, August 18th, Venus and Jupiter are separating, but not too quickly. They'll remain in the same patch of sunrise sky for the rest of the week. A date of special interest is August 23rd when the crescent Moon joins the planets to form a must-see celestial triangle. A video from NASA previews the meeting.

HE SURPRISING POTENCY OF "WEAK" FLARES: For the past month, the sun has been mostly quiet with only a smattering of C- and B-class solar flares. As flares go, these are puny. In fact, when the sun is crackling with flares no stronger than B-class, we often say that "solar activity is very low."

But is it, really? A B-class solar flare packs a bigger punch than is generally supposed. Consider this specimen photgraphed by Harald Paleske of Weißenfels/ OT Langendorf, Germany, on August 17th:

"This was a B8-class flare in sunspot AR2144," says Paleske. "Despite poor seeing, I was able to capture a high-resolution view of the explosion using my 225mm Unigraph solartelescope."

The violence frozen in these snapshots belies the idea that this was a weak explosion. And indeed it was not. A typical B-class solar flare releases as much energy as 100 million WWII atomic bombs. Only on the sun, which is itself a 10²⁷ton self-contained nuclear explosion, would such a blast be considered puny.

So the next time you hear that the forecast calls for "low solar activity," remember ... everything is relative. Today's forecast, by the way, calls for low solar activity with only a 10% chance of M-class solar flares.

CHANCE OF MINOR STORMS: NOAA forecasters estimate a 30% chance of polar geomagnetic storms on August 18th when a faint CME is expected to strike Earth's magnetic field head-on. This is not a major event. Nevertheless, high-latitude sky watchers should be alert for auroras when the CME arrives. Follow the action@spaceweatherman.

MORNING PLANETS: Did you see that? This morning Venus and Jupiter converged in the pre-dawn sky for a spectacular conjunction. At closest aproach they were barely 0.2^o apart. Richard S. Wright Jr. sends this picture from Lake Mary, Florida:

"This was worth setting my alarm for this morning," says Wright. "Jupiter and Venus were so close together, and rapidly rising as the sky brightened. I grabbed my tripod and caught them under my neighbors trees."

The planets are separating now, but not too quickly. They will still be a beautiful pair for the rest of the week. A date of special interest is August 23rd when the crescent Moon joins the planets to form a bright celestial triangle in the eastern pre-dawn sky.

Observing tips: Go outside 60 minutes before sunrise and look east-northeast. No telescope is required. Jupiter and Venus are bright enough to see with the naked eye even from light polluted cities. Try following the bright pair after the dawn sky begins to brighten. A tight conjunction of Venus and Jupiter framed by twilight blue is a great way to start the day. For more information, see this video from NASA.

MORNING PLANETS: Set your alarm for dawn! Venus and Jupiter are converging for a spectacular conjunction in the early morning sky. Closest approach: August 18th. A video from NASA previews the encounter

THE LANDSCAPE OF A COMET: On August 6th, Europe's Rosetta spacecraft rendezvoused with Comet 67P/Churyumov-Gerasimenko and began to fly alongside it. Seven days later, mission scientists released this spectacular view of the comet's double-lobed core:

A closer look reveals many interesting features: While the comet's head (in the top half of the image) is scored with parallel linear features, the neck is peppered with boulders resting on a smooth underlying terrain. In comparison, the comet's body (lower half of the image) is jagged and dimpled by crater-like depressions.

Now imagine this magnificent landscape ruptured by dozens of geysers spewing dust and gas into space. Future pictures may show exactly that. Rosetta will follow this comet for more than a year as it approaches the sun. In 2015, if not sooner, solar heating will activate the comet's icy core, creating a riot of activity the likes of which no spacecraft has ever seen before. Stay tuned for that.

EARTH-DIRECTED ERUPTION: A magnetic filament snaking down the middle of the solar disk erupted on Aug. 15th at approximately 1700 UT. Quick-look data from NASA's STEREO probes suggest that the blast hurled a CME toward Earth. If so, the cloud would probably arrive on or about Aug. 18th

PERSEID METEOR SHOWER--PEAKING NOW: According to the International Meteor Organization, the Perseid Meteor Shower is peaking now with as many as 50 meteors per hour. These rates are sharply reduced, compared to a normal year, because of the glare from the waning supermoon. It is still, however, a significant shower. If it is dark where you live, go outside and look up. Otherwise, try listening to Perseid radar echoes on Space Weather Radio.

Colliding Atmospheres: Mars vs Comet Siding Spring

August 12, 2014: On October 19, 2014, Comet Siding Spring will pass by Mars only 132,000 km away--which would be like a comet passing about 1/3 of the distance between Earth and the Moon.

The nucleus of the comet won't hit Mars, but there could be a different kind of collision.

"We hope to witness two atmospheres colliding," explains David Brain of the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP). "This is a once in a lifetime event!"

Everyone knows that planets have atmospheres. Lesser known is that comets do, too. The atmosphere of a comet, called its "coma," is made of gas and dust that spew out of the sun-warmed nucleus. The atmosphere of a typical comet is wider than Jupiter.

"It is possible," says Brain, "that the atmosphere of the comet will interact with the atmosphere of Mars. This could lead to some remarkable effects—including Martian auroras."

The timing could scarcely be better. Just last year, NASA launched a spacecraft named MAVEN to study the upper atmosphere of Mars, and it will be arriving in Sept. 2014 barely a month before the comet.

MAVEN is on a mission to solve a longstanding mystery: What happened to the atmosphere of Mars? Billions of years ago, Mars had a substantial atmosphere that blanketed the planet, keeping Mars warm and sustaining liquid water on its surface. Today, only a wispy shroud of CO2 remains, and the planet below is colder and dryer than any desert on Earth. Theories for this planetary catastrophe center on erosion of the atmosphere by solar wind.

"The goal of the MAVEN mission is to understand how external stimuli affect the atmosphere of Mars," says Bruce Jakosky of LASP, MAVEN's principal investigator. "Of course, when we planned the mission, we were thinking about the sun and the solar wind. But Comet Siding Spring represents an opportunity to observe a natural experiment, in which a perturbation is applied and we can see the response."

Brain, who is a member of the MAVEN science team, thinks the comet could spark Martian auroras. Unlike Earth, which has a global magnetic field that shields our entire planet, Mars has a patchwork of "magnetic umbrellas" that sprout out of the surface in hundreds of places all around the planet. If Martian auroras occur, they would appear in the canopies of these magnetic umbrellas.

"That is one thing that we will be looking for with both MAVEN and Hubble Space Telescope," says Brain. "Any auroras we see will not only be neat, but also very useful as a diagnostic tool for how the comet and the Martian atmosphere have interacted."

The atmosphere of the comet includes not only streamers of gas, but also dust and other debris blowing off the nucleus at 56 kilometers per second relative to Mars. At that velocity, even particles as small as half a millimeter across could damage spacecraft. NASA's fleet of Mars orbiters including MAVEN, Mars Odyssey and Mars Reconnaissance Orbiter will maneuver to put the body of Mars between themselves and the comet’s debris during the dustiest part of the encounter.

"It's not yet clear whether any significant dust or gas will hit the Mars atmosphere," cautions Jakosky. "But if it does, it would have the greatest effects on the upper atmosphere."

Meteoroids disintegrating would deposit heat and temporarily alter the chemistry of upper air layers. The mixing of cometary and Martian gases could have further unpredictable effects. Although MAVEN, having just arrived at Mars, will still be in a commissioning phase, it will use its full suite of instruments to monitor the Martian atmosphere for changes.

"By observing both before and after, we hope to determine what effects the comet dust and gas have on Mars, if any," says Jakosky.

PERSEID METEOR SHOWER: The annual Perseid meteor shower peaks tonight, Aug. 12-13, as Earth passes through a stream of debris from Comet Swift-Tuttle. Forecasters expect peak rates of 30 to 40 meteors per hour, less than usual because of the glare from the waning supermoon. Observing tips: To reduce the effects of moonlight, pick an observing site with clear, dry air. Also try watching the sky from the moonshadow of a tall building or other obstacle. Many Perseid fireballs will be visible in spite of the glare. [NASA chat]

Unaffected by moonlight, the Canadian Meteor Orbit Radar (CMOR) is scanning the skies above North America for echoes from disintegrating meteoroids. The latest CMOR sky map shows strong activity from the constellation Perseus (PER):

Click to view a radar map of the entire sky. The Perseids are not alone. In the southern hemisphere, a cluster of lesser radiants is also active. Foremost among them is the Southern Delta Aquarids (SDA) probably caused by debris from Comet96P/Machholz. Delta Aquarid fireballs will augment the Perseids south of the equator.

Because of the moonlight, radar may be the best way to observe tonight's shower. You can listen to meteor radar echoes in realtime on Space Weather Radio.

ARS COMET WORKSHOP: On Oct. 19, 2014, Comet Siding Spring will pass so close to Mars that the atmosphere of the comet might interact with the atmosphere of the Red Planet. Today, researchers are gathering at the Johns Hopkins University Applied Physics Laboratory to discuss the encounter. The meeting will be streamed live starting at 8:45 AM EDT on Aug. 11th. Members of the public are welcome to listen and ask questions on Twitter using the hashtag #MarsComet.

WEEKEND SUPERMOON: The full Moon of August 10th was as much as 14% bigger and 30% brighter than other full Moons of the year. Some say that makes it asupermoon. Others retort that it's really not as super as the media has made it out to be. Who's correct? Vesa Vauhkonen of Rautalampi, Finland, took a stab at settling the question with this side-by-side comparison:

"I compared the normal full Moon of March 2014 with the Supermoon of Aug 2014," says Vauhkonen. "In individual images, the difference in size might be difficult to see, but putting them side by side makes the difference clear. I used the same photo settings for both images, so the scaling has no errors."

Supermoons are possible because the Moon's orbit is not a circle, it is an ellipse. One side, perigee, is 50,000 km closer than the other, apogee. On August 10th the Moon became full just as it reached perigee, the point closest to Earth. This caused the Moon to appear authentically bigger and brighter than usual.

More photos of the full Moon, and the landscape of Earth bathed in super-moonlight, may be found in the realtime photo gallery:

QUIET SUN: As the one-month anniversary of the "All-Quiet Event" approaches, the sun's global X-ray output is sinking again. Solar activity is very low. Only one sunspot (AR2135) poses a threat for significant flares, but it seems reluctant to erupt. Follow the action, or lack thereof, @spaceweatherman.

THE SUPERMOON RISES: Tonight's full Moon is the biggest and brightest full Moon of the year. Astronomers call it a perigee moon; the popular term is "supermoon." Stephen Mudge photographed the bright orb rising over the Mormon temple in Brisbane, Queensland, on Aug. 10th:

Supermoons are possible because the Moon's orbit is not a circle, it is an ellipse. One side, perigee, is 50,000 km closer than the other, apogee. Today the Moon becomes full just as it reaches perigee, the point closest to Earth. The perigee supermoon you see tonight is as much as 14% closer and 30% brighter than other full Moons of the year.

DOUBLE SPACESHIP FLYBY: On Fridy, August 8th, Europe's robotic cargo carrier, the "George Lemaitre," flew just 4 miles underneath the International Space Station. In Berlin, Germany, astrophotographer Thomas Becker recorded the close encounter:

"I caught the two spacecraft over the Wilhelm-Foerster-Observatory in Berlin," says Becker. "Bright moonlight completed the scenery."

Loaded with more than seven tons of fuel and supplies, the George Lemaitre (a.k.a. "ATV-5") is scheduled to dock with the ISS on Tuesday, Aug. 12th. Friday's preliminary flyby allowed mission controllers to test a suite of lasers and sensors that may be incorporated into the design of future European spacecraft.

George Lemaitre, the man, was a 20th century Belgian astronomer and physicist credited with proposing the theory of the expansion of the universe. ATV-5, the fifth in Europe's series of Automated Transfer Vehicles for shuttling supplies to the ISS, was named in his honor.

RELUCTANT SUNSPOTS: Sunspot AR2135 has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares. Like every other sunspot that has crossed the solar disk in the past month, however, AR2135 seems reluctant to erupt. Solar activity is low and will likely remain so for the rest of the weekend.

PERSEID METEOR UPDATE The Perseid meteor shower is underway as Earth moves into the debris stream of parent comet Swift-Tuttle. According to the International Meteor Organization, the constellation Perseus is now spitting out meteors at a rate of about 20 per hour. In a normal year, those rates would increase 4- or 5-fold as the shower reaches its peak on August 12-13. But this is no normal year. In 2014, the glare of a supermoon will interfere with Perseid visibility, capping visible meteor rates at no more than ~30 per hour.

Now for the good news: The Perseids are rich in fireballs, and many of those extra-bright meteors can be seen in spite of the lunar glare.

the meteor cut through the moonlight wih ease. In the past week, NASA's network of all-sky cameras has recorded nearly 100 Perseid fireballs over the USA, and more are in the offing. So, note to sky watchers: Don't be put off by the supermoon. A trip to the moonlit countryside on August 12-13 will be rewarded by a display of Perseids, albeit fewer than usual.

A good time to look on those nights might be during the hours after sunset when the Moon is still hanging low in the sky and the constellation Perseus is rising in the northeast. Such an arrangement can produce a special type of meteor called an earthgrazer. Earthgrazers emerge from the horizon and skim the top of the atmosphere above the observer, a bit like a stone skipping across the surface of a pond. An hour's watching might net no more than one or two of this special kind of meteor, but that's plenty. Earthgrazers are colorful and gracefully slow, a rare beauty that makes any meteor-watch worthwhile.

PERSEID FIREBALLS: The full Moon of August 10th is no ordinary full Moon--it's a supermoon, the biggest and brightest of 2014. This has raised concerns that bright moonlight will outshine the Perseid meteor shower, underway now as Earth moves into the debris stream of parent Comet Swift-Tuttle. So far the Perseids are holding their own. In recent nights, observers have reported dozens of Perseid fireballs cutting through the glare.

Play it again. The ghostly warbling sound you hear was a terrestrial radio signal bouncing off the ionized trail of the fireball. This method of detecting meteors is called "forward scatter radar." Ashcraft, who is an amateur radio astronomer, routinely uses this method to monitor meteor activity over his observatory not far from Santa Fe. Lately, he has been recording lots of echoes.

"My radio fireball array and all-sky camera caught this Perseid earthgrazer at 11:30 pm here in New Mexico as the constellation Perseus was coming up over the northern horizon," says Ashcraft. "It caused a dynamic dopplering forward scatter reflection in stereo on two of my radios."

"Even though there is a bright moon at the moment, there will still be some beautiful Perseids over the next few nights," he predicts.

We're in orbit!' Rosetta becomes first spacecraft to orbit comet

(CNN) -- After a 10-year chase taking it billions of miles across the solar system, the Rosetta spacecraft made history Wednesday as it became the first probe to rendezvous with a comet on its journey around the sun.

"Thruster burn complete. Rosetta has arrived at comet 67P. We're in orbit!" announced the European Space Agency, which is leading the ambitious project, on Twitter.

Rosetta fired its thrusters on its final approach to Comet 67P/Churyumov-Gerasimenko, known as "Chury" for short, on Wednesday morning. Half an hour after the burn, scientists announced that the craft had entered into the orbit of the streaking comet.

"After 10 years, five months and four days travelling towards our destination, looping around the sun five times, we are delighted to announce finally 'we are here'," said Jean-Jacques Dordain, ESA's Director General, in a statement.

Europe's Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start."

ESA tweeted a photo of the comet after Rosetta's maneuver. Chury and the space probe now lie some 250 million miles from Earth, about half way between the orbits of Jupiter and Mars, according to ESA.

The first spectacular and detailed images taken from just 80 miles away shows boulders, craters and steep cliffs and are already causing excitement.

"Churyumov-Gerasimenko looks like it's been through the wars!" said Dr Robert Massey of the Royal Astronomical Society in the UK.

"With that odd looking 'neck', either we're looking at two objects that merged together or so much material has been lost in its many passes around the sun that the comet is a shadow of what it started out as.

"The pictures coming back so far look intriguing -- and imagine the kind of scenes we can expect when Philae lands this coming November," he said.

To get to its destination the spacecraft has covered more than three billion miles and as the comet hurtles towards the sun it will reach a speed of about 62,000 miles per hour.

The mission has now achieved the first of what it hopes will be a series of historic accomplishments. In November mission controllers aim to place the robotic lander Philae on the surface -- something that has never been done before.

Previous missions have performed comet fly-bys but Rosetta is different. This probe will follow the comet for more than a year, mapping and measuring how it changes as it is blasted by the sun's energy.

Mission controllers had to use the gravity of Earth and Mars to give the probe a slingshot acceleration to meet its target on the right trajectory. Rosetta also had to be put into hibernation for more than two years to conserve power before being woken up successfully in January this year.

Wednesday's thruster burn was the tenth rendezvous maneuver Rosetta has performed since May to get the probe's speed and trajectory to align with the comet's -- and if any of those operations had failed, the mission would have been lost, according to ESA.

For the next few weeks, ESA says the spacecraft will be in a triangular orbit until it gets to about 18 miles of the surface when it starts its close observations.

Scientists hope to learn more about the composition of comets and perhaps whether they brought water to the Earth or even the chemicals that make up the building blocks of life.

"It really is such a step forward to anything that has come before," project scientist Matt Taylor told CNN.

Rosetta will soon begin mapping the surface of and finding out more about its gravitational pull. This will help to find a suitable landing site for Philae and allow engineers to keep Rosetta in the right orbit.

As comets approach the sun, any ice melts and is turned into an ionized gas tail. The dust produces a separate, curving tail. It's these processes that Rosetta scientists hope to be able to study from close proximity.

Taylor explained that the survey will show the team what the comet nucleus looks like now and when it gets closer to the sun.

"We'll be able to make a comparison to now, when its relatively inert, to when it's highly active ... making this measurement over a year when we're riding alongside at walking pace and observing how a comet works and interacts with the sun," he said.

"We are there for over a year to see this complete development to the extent that you may even be able to measure the decrease in the volume of the nucleus ... see how much material has left the comet."

Chury is known as a short-period comet. It reappears every six years as its orbit brings it close to the sun. Halley's comet has a period of about 76 years and is not due to return close enough to Earth to be visible until 2061. Others only return after thousands of years.

Matt Taylor says it is unlikely that you will be able to see comet 67P with the naked eye but you can follow the progress of the mission onRosetta's blog and find out more with CNN's interactive coverage.

MOSTLY QUIET WITH A CHANCE OF FLARES: Sunspot AR2134 has a delta-class magnetic field that harbors energy for significant eruptions. However, like every other sunspot that has crossed the solar disk in recent weeks, this one seems reluctant to erupt. NOAA forecasters estimate only a 20% chance of M-flaresduring the next 24 hours as the month-long spell of low solar activty continues.

COMET RENDEZVOUS--TODAY! The European Space Agency's Rosetta probe has reached 67P/Churyumov-Gerasimenko and is maneuvering to go into orbit around the comet's core. This is an historic event. After Rosetta goes into orbit, it will follow the comet around the sun, observing its activity from point-blank range for more than a year. Moreover, in November, Rosetta will drop a lander onto the comet's strange surface. Today's events are being streamed live by the ESA.

After 10 years and four billion miles, the European Space Agency’sRosetta spacecraft will arrive at its destination on Wednesday for the first extended, close examination of a comet.

The last in a series of 10 thruster firings over the past few months will slow Rosetta to the pace of a person walking, about two miles per hour relative to the speed of its target, Comet 67P/Churyumov-Gerasimenko, at a distance of about 60 miles.

Photographs have already revealed a surprisingly irregular shape for the 2.5-mile-wide comet, possibly an amalgamation of two icy bodies or a result of uneven weathering during previous flybys. From a distance, the blurry blob initially looked somewhat like a rubber duck. As the details came into the focus, it now more resembles a knob of ginger flying through space.

Continuing a trend of anthropomorphizing, the Rosetta mission managers tweeted a photograph of the comet on Monday with the comment “Do you think I got #67P’s good side yesterday?”

PERSEID METEOR SHOWER: Meteor activity is increasing as Earth plunges deeper into the debris stream of Comet Swift-Tuttle, source of the annual Perseid meteor shower. On the night of Aug 3-4, NASA cameras recorded more than a dozen Perseid fireballs over the USA. Counts are high even though the shower's peak is still more than a week away. To see for yourself, get away from city lights and look up during the dark hours before sunrise. You can also hear the Perseids onSpace Weather Radio.

FIREBALL EXPLODES, SPRAYS COUNTRYSIDE: On Saturday night, August 2nd, NASA meteor cameras detected a fireball that exploded in a flash of light many times brighter than the Moon. It came not from the Perseid debris stream, but rather from the vicinity of the asteroid belt between Mars and Jupiter.

"The meteoroid was about 15 inches in diameter and weighed close to 100 lbs," says Bill Cooke of NASA's Meteoroid Environment Office. "Travelling 47,000 miles per hour, it broke apart in a brilliant flash of light above the Alabama town of Henagar. Our cameras continued to track a large fragment until it disappeared 18 miles above Gaylesville, located near Lake Weiss close to the Georgia state line. At last sight, the fragment was still traveling at 11,000 miles per hour. Based on the meteor's speed, final altitude, and weak doppler radar signatures, we believe that this fireball produced small meteorites on the ground somewhere between Borden Springs, AL and Lake Weiss."

The NASA Meteoroid Environment Office would like to hear from those in the area around Alabama's Lake Weiss who may have heard sonic booms or similar sounds around 10:20 PM Saturday night. Please contact Dr. Bill Cooke at william.j.cooke@nasa.gov with reports.

METEOR ACTIVITY: Meteor activity is increasing as Earth plunges deeper into the debris stream of Comet Swift-Tuttle, source of the annual Perseid meteor shower. Last night alone, NASA cameras recorded more than a dozen Perseid fireballs along with one sporadic bolide (exploding meteor) that might have dropped pieces of itself over the southeastern USA. Visit http://spaceweather.com for video and observing tips.

CHANCE OF FLARES: Sunspot AR2130 is directly facing Earth and it has a complex 'delta-class' magnetic field that harbors energy for strong flares. X-flare alerts are available from http://spaceweathertext.com (text) and http://spaceweatherphone.com (voice).

PLANETS CROSSING AT NOON This weekend, Jupiter and Mercury are in conjunction. Don't bother looking because the meeting takes place in the noontime sky. What human eyes cannot see, however, spacecraft can. Using an opaque disk to block the glare of the sun, the Solar and Heliospheric Observatory (SOHO) is monitoring the encounter:

At closest approach on August 2nd, the two bright planets were less than 1^o apart. If such an alignment occured at night, it would surely be headline news. At noon, its just spaceweather news. Join SOHO for a ringside seat.

MINOR STORM WARNING, CANCELLED: A CME expected to sideswipe Earth's magnetic field on August 2nd has not arrived. The tardy cloud is either off target or moving more slowly than forecasters thought, or both. The chance of a geomagnetic storm this weekend is waning

sunspot AR2132 has a 'beta-gamma-delta' magnetic field that harbors energy for X-class solar flares. Credit: SDO/HM

MINOR STORM WARNING: A CME is heading for Earth. The cloud was hurled into space on July 30th when a magnetic filament on the sun erupted, and it appears to be on course to sideswipe Earth's magnetic field. NOAA forecasters estimate a 30% chance of polar geomagnetic storms on Aug. 2nd when the CME arrives.Aurora alerts: text, voice

AMAZING NEW PHOTO OF THE ROSETTA COMET: Today, the ESA released a new image of Comet 67P/Churyumov-Gerasimenko as seen from the Rosetta probe only 1000 km away. It shows the rough surface of the comet's double nucleus in amazing detail:

The photo was taken on Aug. 1st at 02:48 UTC by Rosetta's OSIRIS Narrow Angle Camera. The dark spot near image-center is an artifact from the onboard CCD.

This new view heightens anticipation for August 6th when Rosetta reaches the comet and goes into orbit around it. Then we will see the strange double-core from point-blank range, and researchers can start to pick touchdown sites for Philae, a lander that will descend to the comet's surface in November.

RADIO BURSTS FROM THE SUN: Yesterday, the loudspeakers of shortwave radios erupted with static. The source of the noise was the sun. "I have been picking up solar bursts on my RadioJove receiver at 20.1 MHz," reports Kevin Palivec of Hawley, Texas. This chart recording displays 10 minutes of activity on August 1st:

The bursts were triggered by an M2-class explosion in the magnetic canopy of sunspot AR2127. The explosion sent shock waves rippling through the sun's atmosphere. Those shock waves, in turn, excited plasma instabilities that emit static-y radio waves. Becase there are a whole variety of plasma instabilites, there is a corresponding variety of radio burst types. Palivec recorded a mix of two: Type II and Type IV.

More solar radio bursts could be in the offing as sunspot AR2127 and nearby sunspot AR2130 both crackle with M-class solar flares. Visit NASA's RadioJove website to find out how to build your own receiver--and listen up.

Asteroid	Date(UT)	Miss Distance	Size
2014 OW3	Jul 29	9.6 LD	137 m
2002 JN97	Aug 2	61.4 LD	2.0 km
2014 OV299	Aug 6	9.5 LD	23 m
2014 OF300	Aug 7	3.8 LD	22 m
2001 RZ11	Aug 17	34.2 LD	2.2 km
2013 WT67	Aug 17	16.1 LD	1.1 km
2013 RZ53	Sep 9	1.9 LD	3 m
2002 CE26	Sep 9	47.9 LD	1.8 km
2009 RR	Sep 16	2 LD	34 m
2006 GQ2	Sep 19	65.9 LD	1.1 km
2009 FG19	Sep 26	34.6 LD	1.1 km
2014 NE52	Sep 30	61.2 LD	1.0 km
2001 EA16	Oct 7	35.5 LD	1.9 km

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