Universe Today

October 1, 2009December 21, 2015 by Nancy Atkinson

Podcast: Binary Stars

Artists illustration of a cataclysmic variable — Artist's illustration of a cataclysmic variable

Did you know that our Solar System is a rarity with its single star? Astronomers believe that most star systems out there actually contain 2 or more stars – imagine seeing a sky with 4 suns. These binary and multiple star systems are a great target for new astronomers, and the dynamics of multiple stars keep astrophysicists busy too. Let’s take a look at what it would be like to live on Tatooine – a good movie version of a planet orbiting binary stars.

Click here to download the episode.

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Binary Stars show notes and transcript.

September 30, 2009April 26, 2016 by Tammy Plotner

The Sky-Watcher AZ4 102 Refractor Telescope… How Sweet It is!

If you’re looking for a quality refractor telescope that costs well under $400 and performs like it should cost twice as much – then you’re really going to want to take a look at the Sky-Watcher AZ4 102 Refractor Telescope. I had read some posts on the Bad Astronomy Universe Today forum about how Sky-Watcher was a new comer into the industry and people were expressing their concerns about the quality of the telescopes they manufacture. I can understand not wanting to take a chance with a fairly unknown company – so I did the logical thing. I asked for one…

According to their site: “At Sky-Watcher USA our only mission is serving the needs of serious amateur astronomers. Sky-Watcher USA is a wholly owned subsidiary of Synta Optical Technology, the world’s largest manufacturer and distributor of astronomical telescopes. Sky-Watcher is a prestigious global brand renowned for technical innovation, award-winning industrial design, and a reputation for high quality workmanship. Sky-Watcher constantly strives to introduce new and improved instrumentation to enhance the amateur astronomer’s capabilities to push the boundaries of personal exploration.”

Those are some mighty fine words, but what I really wanted to know is how well the product would live up to them. So let’s start with first things first, eh? Sky-Watcher doesn’t just hang in the USA. If you’re looking for a Sky-Watcher telescope, you aren’t limited because they have subsidiaries in both Canada and Europe. This is good news for those of you who often desire a particular type of telescope and have difficulties with shipping. The next bit of good news you’ll also like to hear is the branch company prices are all competitive with the monetary scale in the area. In other words, what a Sky-Watcher telescope costs on one exchange rate is going to be pretty daggone close on the other.

Hmmm… A company that’s not out to get you because of where you live? I like that…

Next up? Investigate Synta Optical. Rumor has it they’ve team with Celestron as well as Sky-Watcher. Well, it’s not a rumor – it’s true – and Suzhou Synta Optical Technology Co., Ltd. of China is proud to be part of it. The company offers advanced equipment, such as multi-coating machines, interference meters (Zygo brand), collimators and other instruments which are used for manufacturing optical products. And when it comes to optics, you can love it or leave it, but Celestron consistently has some of the finest optics and durable mechanics that I know, so we’re looking at a good global reputation here. If Synta is also supplying SkyWatcher, then why should the quality be any less for their name?

Hmmm… A company that’s going to produce durable quality? I like that…

Next up? New and improved. And that’s where we get down to the bottom line, isn’t it? What can be new and improved upon the time honored telescope designs we’ve all known and trusted for many, many years? Then let’s try high quality and affordability – that would be a welcome “new and improved” for us all.

So, now it’s time to open the box the Sky-Watcher AZ4 102 Refractor Telescope came in and check it out. I was immediately impressed with the quality of the optical tube. From its glistening black with gold fleck paint, to its spotless white trim, this is one very well put together refractor. No edge is left unturned or cheaply done. At around 14 pounds, the AZ4 102 isn’t a lightweight and Sky-Watcher’s advertisements don’t even express how well made it really is. We’re talking smooth quality rack and pinion focusing with aluminum knobs – no slop in the focus – just fluid workings with enough tension that you’re not going to overshoot your mark easily. One glance at the sparkling objective and you’re going to see 2-element, color corrected achromatic lenses that are fabricated to the highest optical standards from Grade-A Crown and Flint optical glass. Each lens set is individually pitch-polished, and hand figured by a master optician ensuring premium optical performance. Each lens system is air-spaced with high transmission optical coatings – not glued together like more inferior models.

Further into the box I find the Sky-Watcher AZ4 mount – known as the “Rock”. Again, I’m impressed with the quality for the price. Both the mount and tripod head are constructed of rigid, cast aluminum and the tublar tripod legs are 1.75″ diameter heavy duty aluminum as well. Assembly was quick and easy and I was delighted with how well centered the weight of the scope and mount fits over the tripod. Unlike some other major brands of inexpensive refractors on alt-azimuth mounts, we’re looking at good quality here… thrust-bearing surfaces well lubricated and teflon bearings… the control knobs work easily and mechanically perfect to allow you to set just the right amount of tension to make everything work with ease.

Next come the accessories. We’ve got 25mm and 10mm four-element Plossl eyepieces, a 45 degree diagonal and a red dot finder. (Yes, there’s even planetarium software, too!) While these accessories aren’t going to set any records as super high quality, they also have absolutely nothing to be ashamed of. The eyepieces and diagonal are above average, and while I’m not real keen on red dot finders, I’m also perfectly capable of using them. Once everything is together, all we need to do is wait on dark…

Refractors have a reputation for excellence on planetary objects and right now Jupiter is prime. Not only are we giving this scope first light – but we’re doing so on a cool, very steady 9/10 atmospheric platform with sweet and easy 6.0 limiting magnitude with a score of better than 8/10 on clarity. With the 25mm in a 1000mm focal length scope, we’re talking roughly 40X power and Jupiter is small and crystal clear. Immediately you could discern dimension in the Galiean moon’s positions and absolutely no color fringing was present. Drop in the 10mm and now we’re talking 100X and details begin snapping out like crazy. The larger moons can be perceived as orbs and striations and swirls in the different zonal belts become very noticeable. Again, there’s no spurious color… No aberration. No ghosts. Just tiny pinpoint stars where Jupiter’s “light pollution” doesn’t influence the picture and a razor sharp planet.

Hmmm… A 4″ chunk of glass that’s going to produce cutting edge images? I like that…

Needless to say, I watched Jupiter for a very long time. Again, I’m impressed (and so were the other discerning astronomers who were also observing at the time) with the mount quality and it lives up to its reputation of being a “Rock”. Usually I do not favor high magnification factors on an un-driven scope, either. But once you’ve set the tension and angle to your liking, you can basically guide the Sky-Watcher AZ4 102 Refractor Telescope with the touch of a finger. Just a gentle pressure to keep the scope tracking and virtually no backwash from the mount moving around.

Of course, I had to do deep sky, too. How did it perform? Reality check. It performs like a 4″ aperture telescope. the AZ4 102 isn’t going to gather more light than what its capable of – nor will it resolve better than its theoretical limitations. But… I want to push those limitations. After all, its supposed to “enhance the amateur astronomer’s capabilities to push the boundaries of personal exploration”. So… Show me.

Using an undisclosed manufacturer’s 2mm – 4mm Click-Stop Zoom eyepiece, I took this telescope to the edge and beyond. We’re talking between 500X and 250X on one of the toughest multiple stars out there – Gamma Andromeda. Before you start thinking I don’t know my business, then think again. Almach’s two primary stars, Gamma 1 and Gamma 2, are easy at even low power. Again, I am impressed with the Sky Watcher 102’s performance on color, because a warm, golden yellow and azure blue makes for a beautiful pair – but what I want to see is what I know can be done. Gamma 2 is also a binary with a .5 arc second separation. What did I find out? At around a magnitude dimmer than its companion and so very close, you have to wait on a moment of perfect stability – but brother? It’s there. You’re not going to drive a truck through the separation, but neither can you deny it once you’ve seen it.

Hmmm… A 102mm f/9.8 achromatic lens resolving out tight fits and showing great airies? I like that…

Once I’d driven it to the limits, it was simply time to relax and let the Sky-Watcher AZ4 102 Refractor just have a good time with the night. Colorful objects like the “Blue Snowball” planetary, pinpoint stars in targets like Messier 15, drooling on the Andromeda Galaxy and companions, and returning over and over again to Jupiter to watch the moons shuttle around. Yep. We stayed up all night, ending with the Orion nebula. For those of you who might wonder about the quality of a Sky-Watcher telescope? Stop wondering, because this model wasn’t the only one star tested tonight either. I guarantee you that you will not be disappointed in the quality of the telescope, nor its performance.

Hmmm… A Sky-Watcher AZ4 102 Refractor Telescope? How sweet it is!

I would sincerely like to express my appreciation to Elena Gonzalez and Joe Gordon of Sky-Watcher USA for allowing me the opportunity with this fine refractor and to the company itself for producing several other extremely fine pieces of equipment that were also tested on this night. (Future reviews will be coming!) If you are interested in purchasing a Sky-Watcher telescope, be sure to visit with their premier dealers: Skies Unlimited, Scope City, OPT Telescope, Adorama, Astronomics, Optics Planet, Great Red Spot, Telescopes.com and Orion.

September 30, 2009December 24, 2015 by Nancy Atkinson

LRO Provides Flashback to 1966

LROC image of Surveyor 1 on the Moon. NASA/GSFC/Arizona State University

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On June 2, 1966 the Surveyor 1 spacecraft soft landed on the Moon, the first US spacecraft to set down on another body. Now, 43 years later the Lunar Reconnaissance Orbiter Camera has spotted this historic spacecraft, sitting silently on the Moon’s surface. The scene shows the spacecraft (annotated with an arrow, and the shadow shows up very well) just south of a 40 m diameter crater and about 110 m northwest of a 190 m diameter crater lined with boulders. The landing site is in the northeast corner of the Flamsteed Ring, a 100 km diameter impact crater almost completely buried by mare lavas such that all that remains exposed is the upper part of the original crater rim.

Surveyor 1 took its own picture on the Moon back in 1966. Credit: NASA

Surveyor 1 collected over 11,000 images, most during the first lunar day between landing and July 7, 1966. The spacecraft continued to operate until January 7, 1967. The Surveyor images demonstrated that the lunar surface was strong enough to support a landed vehicle or a human. The detailed images also indicated that the surface was composed of a granular material interpreted to be produced by the impact of various size meteors over billions of years.

And 43 years later we figured out some H20 and OH were also part of the mix.

See the entire image swath at the LROC site.

Source: LROC

September 30, 2009December 24, 2015 by Nancy Atkinson

Where In The Universe #73

Ready for another Where In The Universe Challenge? Here’s #73! Take a look and see if you can name where in the Universe this image is from. Give yourself extra points if you can name the spacecraft responsible for the image. As usual, we’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.

UPDATE: The answer has been posted below.

Doesn’t the Moon look good in pink? Yes, this is our Moon, as seen in gamma rays by the Compton Gamma Ray Observatory. If you could see gamma rays – photons with a million or more times the energy of visible light, the Moon would appear brighter than the Sun according to astronomers who worked with the Energetic Gamma Ray Experiment Telescope (EGRET), which toiled in orbit on board Compton from April 1991 to June 2000.

EGRET’s gamma-ray vision was not sharp enough to resolve a lunar disk or any surface features, but its sensitivity revealed the induced gamma-ray moonglow.

More info about Compton Gamma Ray Observatory.

Check back next week for another WITU challenge!

September 30, 2009December 24, 2015 by Nancy Atkinson

GOCE Satellite Begins Mapping Earth’s Gravity in Lower Orbit Than Expected

Anaglyph images created from an ESA video animation of global gravity gradients. A more accurate global map will be generated by ESA's GOCE craft. Credit: ESA and Nathaniel Burton Bradford.

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Is Earth’s gravity field as intriguing and misshapen as this image above? We’re about to find out. The sexy looking Gravity field and steady-state Ocean Circulation Explorer or GOCE satellite has completed its calibration and is now in its science orbit to map the tiny variations of Earth’s gravity in unprecedented detail. And it turns out the sun’s current period of low solar activity has a side benefit for the GOCE mission. Less solar activity means a calmer environment for GOCE in its low Earth orbit, so its current orbit of 255 km is a few kilometers lower than engineers had originally planned. This is good news – the gravity measurements being made at the moment will be even more accurate.

“The completion of the commissioning and first in-flight calibration marks an important milestone for the mission, ” said Rune Floberghagen, ESA’s GOCE Mission Manager. “We are now entering science operations and are looking forward to receiving and processing excellent three-dimensional information on the structure of Earth’s gravity field.”

Anaglyph created from an ESA GOCE craft animation. Credit: ESA and Nathanial Burton Bradford

Gravity is stronger closer to Earth, so GOCE was designed to orbit as low as possible while remaining stable as it flies through the fringes of our atmosphere. GOCE’s sleek aerodynamic design helps this the satellite to cut though the tenuous fringes of Earth’s atmosphere at this low altitude. Moreover, the electric ion thruster at the back continuously generates tiny forces to compensate for any drag that GOCE experiences along its orbit.

To help avoid drag and ensure that the gravity measurements are of true gravity, the satellite has to be kept stable in ‘free fall’. Any buffeting from residual air at this low altitude could potentially drown out the gravity data.

Space gradiometry and the use of the sophisticated electric propulsion are both ‘firsts’ in satellite technology, so the commissioning and calibration were particularly important for the success of the mission. This phase was completed in the summer, ready for the tricky task of bringing GOCE down to its operational altitude, which took a couple of months.

Worldwide gravity gradients from simulations. GOCE is now gathering data such as shown here to map Earth's gravity with unprecedented accuracy and spatial resolution. Credit: ESA

Over two six-month uninterrupted periods, GOCE will map these subtle variations with extreme detail and accuracy. This will result in a unique model of the ‘geoid’ – the surface of an ideal global ocean at rest.

A precise knowledge of the geoid is crucial for accurate measurement of ocean circulation and sea-level change, both of which are influenced by climate. The data from GOCE are also much-needed to understand the processes occurring inside Earth. In addition, by providing a global reference to compare heights anywhere in the world, the GOCE-derived geoid will be used for practical applications in areas such as surveying and leveling.

Stay tuned for some unique data about our home planet from GOCE.

Thanks to Nathanial Burton-Bradford for the terrific anaglyphs he created from a GOCE animation. See more of Nathanial’s images on his Flickr page.

Source: ESA

September 30, 2009December 24, 2015 by Nancy Atkinson

Soyuz Launch Video

Soyuz launch on Sept. 30. Credit: NASA/Bill Ingalls.

The Soyuz TMA-16 spacecraft launched today at 07:14 GMT (2:14 CDT) from the Baikonur Cosmodrome in Kazakhstan. On board were Soyuz Commander Max Suraev, NASA Flight Engineer Jeff Williams and spaceflight participant Guy Laliberte, founder of Cirque du Soleil . They will arrive at the International Space Station on Friday.

If you’ve ever wondered about some of the unusual rituals the Russians partake in before a launch, an article on Discovery Space outlined the following traditions witnessed over the years by reporters for The Associated Press, or reported in the Russian media:

CARNATIONS FOR YURI: Before leaving for Baikonur, crew members lay red carnations at the monuments of the first Soviet cosmonauts in Star City outside Moscow and visit the office of Yuri Gagarin, the first human in space, and write their names in the visitors’ book.

ARRIVAL: Cosmonauts arrive in Baikonur on different planes and without their spouses. They check into the Kosmonaut hotel and walk down the alley where every tree was planted by cosmonauts who successfully returned from space.

MOVIE NIGHT: On the night before the launch, the cosmonauts watch “The White Sun of the Desert,” a 1969 comedy about a Russian soldier fighting in Central Asia.

MUSIC: Before leaving for the launch, the cosmonauts sip champagne and leave their signatures on the doors of their hotel rooms. Then they ride aboard a minibus to the launch pad listening to “Grass Near Home,” a 1983 hit of Soviet rock band The Earthlings.

BLESSING: After the Soviet era, black-robed Orthodox priests began to bless each rocket before launch.

SOAKING THE STAND-INS: 30 minutes before the launch, when the main crew is sealed in the spaceship, the cosmonaut’s stand-ins, who act as backup for the regular crew, are “soaked” by gulping vodka shots with journalists at a shabby cafeteria near the launch pad.

SOILING THE WHEEL: The cosmonauts get out of the bus near the rocket and urinate on its right rear wheel. The rite dates back to Gagarin himself, who reportedly did not want to soil his space suit during the takeoff.

MASCOT: A mascot, usually a stuffed animal named “Boris,” hangs in front of the crew. When the toy begins to float, the cosmonauts know they are approaching near zero gravity.

LANDING: After the landing in Kazakh steppe, the cosmonauts sign their capsule, which is charred by the heat of re-entry, and drink a bottle of vodka stashed before the launch. After a helicopter ride to Baikonur, they plant a tree near the Kosmonaut hotel.

RETURN TO MOSCOW: Upon their return to Star City outside Moscow, they pay a final visit to Gagarin’s monument and go to the church of St. Prince Daniil of Moscow, where they kiss the saint’s relics.

Source: Discovery Space

September 30, 2009December 24, 2015 by Nancy Atkinson

MESSENGER Went Into Safe Mode Approaching Mercury

This unnamed basin was imaged as MESSENGER approached Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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The MESSENGER spacecraft went into safe mode just before its closest approach of Mercury on Sept. 29. Although the instruments were taking data as the spacecraft came near the planet during this third flyby of the mission, after going into safe mode, no further data or pictures were obtained. This means the expected science investigations from the flyby were not executed. However, as Emily Lakdawalla pointed on in the Planetary Blog, the most important purpose of this flyby was the last gravity assist that will allow MESSENGER to enter orbit in 2011, and to that end, the flyby was a complete success. Additionally, the images taken during the approach are of the 5% of Mercury that was previously unseen, as in the image above of this unnamed basin. See more images from the approach below.

A High-resolution Look over Mercury's Northern Horizon. Credit: MESSENGER team

MESSENGER skimmed just 142 miles (228 km) above Mercury at closest approach, and then whipped behind the planet for the gravity assist. During the operation, five MESSENGER “fellows” or master teachers were reporting the flyby live via Twitter. Gene Gordon (Porchdragon on Twitter) reported that unexpectedly, the signal dropped from MESSENGER before the expected signal blackout while flying on the other side of Mercury: “Suddenly room got quiet and people hovering near computers. Unexpected signal drop just occurred. Sense of nervousness seems to have happened.”

Read Gene Gordon’s blog post about his experiences.

The MESSENGER team had to wait over 50 minutes until the spacecraft emerged from behind Mercury, and were relieved to be able to resume contact. As of Wednesday morning, the spacecraft was operating normally, and the reason for the signal drop was unclear. At a briefing, MESSENGER team members said the spacecraft went into safe mode when it entered Mercury’s shadow and tried to switch to battery power. The team is still looking into why this anomaly occurred.

A little less than half of the”extra” science goals for the flyby were accomplished. See our previous article on the science goals for the flyby. Following this flyby. only the polar regions of Mercury have never been seen.

Previously unseen side of Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

MESSENGER made its closest approach on Tuesday at about 5:55 p.m. EDT (2155 GMT), zooming at speeds of about 12,000 mph (19,312 kph). Mercury’s gravity was expected to slow MESSENGER by about 6,000 mph (9,656 kph) during the flyby and place it on track to enter orbit of Mercury in March 2011.

See all the images acquired by the third flyby here.

Learn more about MESSENGER and the two previous flybys which occured in 2008 here.

Lead image caption: his unnamed impact basin was seen for the first time yesterday during MESSENGER’s third flyby of Mercury. The outer diameter of the basin is approximately 260 kilometers (160 miles). This basin has a double-ring structure common to basins with diameters larger than 200 kilometers (about 125 miles).

Additional information from Jeff Goldstein on Twitter (doctorjeff) was also used in this article

September 30, 2009December 24, 2015 by Nancy Atkinson

Hubble Sees Galaxies Stripped by Ram Pressure

This composite shows the two ram pressure stripping galaxies NGC 4522 and NGC 4402. Credit: NASA & ESA

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Strange forces of nature are stripping away gas from galaxies in the Virgo cluster. An extremely hot X-ray emitting gas known as the intra-cluster medium permeates the regions between galaxies inside clusters and, as fast moving galaxies whip through this medium, strong winds tear through galaxies distorting their shape and even halting star formation with a process known as “ram pressure stripping.” Hubble spied two galaxies “losing it” to these forces.

Ram pressure is the drag force that results when something moves through a fluid — much like the wind you feel in your face when bicycling, even on a still day — and occurs in this context as galaxies orbiting about the centre of the cluster move through the intra-cluster medium, which then sweeps out gas from within the galaxies.

The two galaxies — NGC 4522 and NGC 4402 – were imaged by the old Advanced Camera for Surveys on Hubble before it suffered from a power failure in 2007. Astronauts on Servicing Mission 4 in May 2009 were able to restore ACS during their 13-day mission.

This image shows NGC 4522 within the context of the Virgo Cluster. Credit: NASA, ESA and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

The spiral galaxy NGC 4522 is located some 60 million light-years away from Earth and it is a spectacular example of a spiral galaxy currently being stripped of its gas content. Astronomers estimate the galaxy is moving at more than 10 million kilometers per hour, and its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. A number of newly formed star clusters that developed in the stripped gas can be seen in the Hubble image.

The image provides a vivid view of the ghostly gas being forced out of it. Bright blue pockets of new star formation can be seen to the right and left of centre. The image is sufficiently deep to show distant background galaxies.

The image of NGC 4402 also highlights some telltale signs of ram pressure stripping such as the curved, or convex, appearance of the disc of gas and dust, a result of the forces exerted by the heated gas. Light being emitted by the disc backlights the swirling dust that is being swept out by the gas. Studying ram pressure stripping helps astronomers better understand the mechanisms that drive the evolution of galaxies, and how the rate of star formation is suppressed in very dense regions of the Universe like clusters.

Source: Hubble Science Center

September 29, 2009December 24, 2015 by Nancy Atkinson

LRO Takes Second, Closer Look at Apollo 11 Landing Site

LROC's second look at the Apollo 11 Landing Site [NASA/GSFC/Arizona State University]. Click for larger version.

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The Lunar Reconnaissance Orbiter Camera has taken a second look at the Apollo 11 landing site. These images were taken before LRO reached its science orbit of 50 km (31 miles) above the Moon, but the lighting is different from the previous images it took of this region, providing more detail and a whole new look at this historic site. This time the Sun was 28 degrees higher in the sky, making for smaller shadows and bringing out subtle brightness differences on the surface. The look and feel of the site has changed dramatically. See below for a close-up view.

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The astronaut path to the TV camera is visible, and you may even be able to see the camera stand (arrow). You can identify two parts of the Early Apollo Science Experiments Package (EASEP) – the Lunar Ranging Retro Reflector (LRRR) and the Passive Seismic Experiment (PSE). Neil Armstrong’s tracks to Little West crater (33 m diameter) are also discernable (unlabeled arrow). His quick jaunt provided scientists with their first view into a lunar crater.

Nice going LROC!

This article was edited on Sept. 30 to correct a mistake about LRO’s orbit at the time these images were taken.
See our previous article on the first round of LROC’s images of various Apollo landing sites.

Source: LROC

September 29, 2009December 24, 2015 by Brian Ventrudo

Cosmic-Ray Intensity Hits 50-Year High

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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.”

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.”

“We’re experiencing the deepest solar minimum in nearly a century,” says Dean Pesnell of the Goddard Space Flight Center, “so it is no surprise that cosmic rays are at record levels for the Space Age.”

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 solar 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.

“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 (IMF) down to only 4 nanoTesla (nT) from typical values of 6 to 8 nT,” he says. “This record-low IMF undoubtedly contributes to the record-high cosmic ray fluxes.”

(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.

(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 the wavy folds. That is the “heliospheric current sheet,” a vast transition zone where the polarity of the sun’s magnetic field changes from plus (north) to minus (south). The current sheet is important because cosmic rays tend to be guided by its folds. Lately, the current sheet has been flattening itself out, allowing cosmic rays more direct access to the inner solar system.

“If the flattening continues as it has in previous solar minima, we could see cosmic ray fluxes jump all the way to 30% above previous Space Age highs,” predicts Mewaldt.

Earth is in no great peril from the extra cosmic rays. The planet’s atmosphere and magnetic field combine to form a formidable shield against space radiation, protecting humans on the surface. Indeed, we’ve weathered storms much worse than this. Hundreds of years ago, cosmic ray fluxes were at least 200% higher than they are now. Researchers know this because when cosmic rays hit the atmosphere, they produce the isotope beryllium-10, 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.

“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.