How large is the heliosphere? The region of interstellar space dominated by the Sun? The Voyager 1 spacecraft has a partial answer: much larger than expected!

The heliosphere, composed of the sun’s magnetic field and a high-velocity stream of charged particles called the solar wind, creates an enormous bubble around our solar system. The charged particles move at about a million miles per hour, only slowing down when they near the region where the pressure of interstellar gas dominates. We thought Voyager 1, our farthest spacecraft, had arrived at edge of the heliosphere, but there is something fishy about Voyager 1’s new data.

Launched in 1977, the twin spacecraft Voyager 1 and Voyager2 have both entered an area called the heliosheath, where the solar wind slows, even though they’re headed in different directions away from the Sun. Voyager 1 lies farthest away, 11 billion miles from Earth, and at this distance it encountered a “magnetic highway.” Here the Sun’s magnetic field connects with the interstellar magnetic field, allowing for an exchange of charged particles between inside and outside the heliosphere.

Voyager 1 measured the highest rate of change so far between incoming and outgoing particles. “We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway,” said Stamatios Krimigis, the low-energy charged particle instrument’s principal investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. In this same region, scientists first detected the low-energy cosmic rays that originate from dying stars.

This should indicate that the spacecraft has reached interstellar space, except scientists have not yet seen the final indicator: an abrupt change in the direction of the magnetic field.

“If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the Sun’s magnetic field,” said Edward Stone, Voyager project scientist at the California Institute of Technology in Pasadena.

So how much farther does Voyager 1 need to travel until it reaches interstellar space? Scientists estimate several months or even years until Voyager 1 experiences a change in magnetic field direction. For now, they have named this strange zone the heliosheath depletion region. Catchy, eh?

Stay tuned for more Voyager discoveries from the edge of interstellar space!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA/JPL-Caltech

The surface temperature of the Sun is about 6,000 Kelvins, while the outer edge of the Sun’s atmosphere, called the corona, can reach millions of Kelvins. Normally, we think of things cooling down the farther they get from an energy source… So how can temperature increase with distance from the Sun’s surface?

The Interface Region Imaging Spectrograph (IRIS) spacecraft launches from the Vandenberg Air Force Base in California on June 27th, with the intention of studying how the corona gets so hot.

“I wonder if maybe we were staring too hard at the corona to understand the corona,” says IRIS scientist Charles Kankelborg, a physicist at Montana State University. “It may be that by backing out we can get some vital clues to what’s happening.”

Between the Sun’s surface and the corona lies a layer of plasma called the chromosphere. Scientists hope that studying this area of lower atmosphere will help them uncover the reason behind the Sun’s strange temperature patterns.

From Earth, we can only observe the layer in question during a total solar eclipse, when the Moon blocks the Sun, and observers can see the halo of glowing light behind the Moon. For IRIS to see this section of sun, it will take images at temperatures between 4,500 Kelvins and 65,000 Kelvins, and ultraviolet spectra between 4,5000 Kelvin and 107 Kelvin.

IRIS is specially designed to target this little understood region of the Sun’s atmosphere. The spacecraft will follow a polar orbit—always facing the Sun—to trace the flow of energy and plasma from the lower layer of the Sun’s surface through the chromosphere and into the corona. Detailed information on this process could give astronomers an archetype for other stellar atmospheres.

Dr. Alan Title, IRIS principal investigator and physicist at the ATC Solar and Astrophysics Laboratory in Palo Alto, is excited for the launch. “With IRIS, we have a unique opportunity to provide significant missing pieces in our understanding of energy transport on the Sun. The complex processes and enormous contrasts of density, temperature and magnetic field within this interface region require instrument and modeling capabilities that are now finally within our reach.”

The launch takes place on Thursday, so the newest data about our closest star are coming soon!

You can watch the launch here at 6:00pm PDT!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA

Earth’s neighborhood just got a little larger.

Astronomers thought that Earth was located on a spur of an arm of the Milky Way… until data from the Very Long Baseline Array telescopes suggested that we could be located closer to the center.

While it’s simple to observe a bird’s-eye view of other galaxies, models of the Milky Way are inaccurate due to Earth’s limited vantage point. We are attempting to measure an entire galaxy using only Earth’s narrow perspective, and at the center of our galaxy is a large bulge, blocking about half of the Milky Way from view.

To make the best model possible, astronomers use a technique called parallax. Measurements are taken from locations on either side of the sun to give multiple perspectives of our location in the sky. Then, astronomers use trigonometry to calculate where we might reside in comparison to distant objects.

At the center of the Milky Way is a supermassive black hole, whose gravitational pull is capable of keeping 200–400 billion stars in orbit around the galaxy. Measurements from NASA’s Spitzer Space Telescope revealed that these stars are oriented in two arms that spiral around the black hole.

“Based on both the distances and the space motions we measured, our Local Arm is not a spur,” said Alberto Sanna, a postdoctoral fellow with the Max-Planck Institute for Radio Astronomy (MPIFR). “It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment.”

Sanna and his colleagues presented their research this week at the American Astronomical Society meeting, held in Indiana.

Astronomers are creating increasingly accurate models of the Milky Way and every new finding tells us more about the entire universe.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA

We’ve reported on solar storms before, especially NOAA’s and NASA’s urge to prepare and educate agencies and individuals as we head into the solar maximum.

When a solar flare and coronal mass ejection (CME) erupted from the Sun around 9:00 p.m. PDT on January 23, satellites captured the events in stunning detail. The Bad Astronomer offers a great video and description of the events and their power on his Discover blog.

These massive storms affect us here on Earth in many different ways, both beautiful and bad. The beautiful? Aurorae in stunning detail and farther reaches than usual. Universe Today offers two articles on aurora cause and effect; the Geophysical Institute offers a forecast and locations to view the displays.

The bad? Power surges and outages, satellite and radio communication interruptions, even exposure to radiation for astronauts. Luckily, as solar storms go, this recent one is only reaching G1 levels on NOAA’s storm scale—G5 is the highest.

Still, there were reports of a power surge in Norway yesterday and news of airline companies rerouting polar flights to avoid disruptions of aircraft communications.

With satellites such as NASA’s SDO and SOHO constantly gathering data on the Sun from every angle and NOAA interpreting the data for the general public, it appears that the news outlets were ready for anything. Score one for preparedness!

Image: SDO/NASA

This image was left out of the lot—but it is one of the coolest pictures of the sun I’ve ever seen.

Earth-sized exoplanets are plentiful, read the headlines yesterday. UC Berkeley researchers, publishing in the journal Science, report ^“that 23% of stars harbor a close-in Earth-mass planets (ranging from 0.5 to 2.0 Earth masses).” As the 80beats blog in Discover reports, “As is always the difficulty with planet hunting, ‘Earth-size’ is not ‘Earth-like.’” Most of these are too close to their parent star—hot, hot—to be inhabitable. Nature’s The Great Beyond has a great, concise blog post about the news, “There’s no place like home?”—check it out for more info.

Another science headline that caught our eye this week was from the BBC, “Sea urchins tolerate acid water.”

Sea urchins are likely to be able to adapt to increasingly acidic oceans resulting from climate change, according to new research.

Are they the cockroaches of the sea? We asked our sea urchin scientist (actually, Curator and Department Chair of Invertebrate Zoology and Geology here at the Academy), Rich Mooi, about the news article. He was unable to find the actual research online, and found many holes in the BBC’s piece:

I cannot see how the idea that these urchins will “adapt” to dropping pH or “tolerate acid water” can be reconciled with the finding that the larvae deposit less calcium carbonate under lower pH conditions.  Successful metamorphosis and subsequent development of the skeleton in the young adult is heavily dependent on the amount of calcium carbonate that the larvae start out with…

The article quotes the researchers on the subject of carbon sinks and carbon budgets, suggesting that “echinoderms currently contribute more than 5% to the total removal of inorganic carbon from the surface ocean to the deep sea.”  This is an overestimate of rather large proportions….

Overall, this study only used the larvae of a single, shallow-water species of common urchin.  The results are interesting as far as that goes, but the broader implications of the work need so much more investigation that the article seems more sensational than is justified.

So don’t believe everything you read…

What did you find unbelievable in science news this week? Let us know.

According to Universe Today:

There was a C3-class solar flare, a solar tsunami, multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection (CME) and more.

(In a separate, very recent post, Universe Today reported that there are actually four CMEs.)

Solar scientists are thrilled! “This has been an unusually quiet solar cycle,”(Universe Today) and the sun is just now waking up, heading for its solar max in May 2013.

This “awesome solar phenomena”(Wired) is also good news for us non-scientists. Wired reports that:

The event also caused a coronal mass ejection to head directly toward earth, which may mean people in the northern latitudes will be treated to auroras around August 3.

Can’t solar flares also mean trouble? This one isn’t big enough. According to MSNBC:

The X-ray blast rated a C3 on the Space Weather Prediction Center’s scale, which suggests there’ll be no disruption for power grids, satellites, astronauts on the International Space Station or navigation services on airplanes.

So depending on your location (San Francisco seems too far south in the current NOAA POES satellite image), sit back, take a look at the skies tonight and tomorrow and enjoy the pretty picture show. (Universe Today has just posted possible times of the auroras.)  And even if you can’t see the auroras, you can see SDO’s amazing video of the activity here or here.

Image: NASA/SDO

Though it has benefited greatly from the power of online connectivity, citizen science is not a new concept, it’s not all astronomical in nature, and it doesn’t necessarily require a computer.

The oldest citizen science project is the Christmas Bird Count, a census of birds of the Western Hemisphere that was started by the Audubon Society in 1900.  One of the newest is the campaign to monitor the eclipsing binary star system Epsilon Aurigae, where every 27 years one component of the star system blocks the other from view for about 2 years.

In 2007, the Citizen Science Alliance launched an online project called Galaxy Zoo, inviting guests to log in and classify distant galaxies by their shapes—spiral, barred spiral, edge-on, or irregular.  An instant hit, Galaxy Zoo became enormously popular and opened the door for additional projects that included observations of merging galaxies, searches for solar flares and supernovae, and, most recently, classification of features on the Moon, all under the broad project name “Zooniverse”.

Zooniverse follows in the footsteps of one of the best-known online popular science projects, SETI@home, based at the University of California’s Space Sciences Lab and which was launched in 1999.  A more passive approach, SETI@home uses the idle-time on subscribers’ computers to activate a screensaver that doubles as a signal analyzer. The analyzer searches downloaded packages of signal data detected by radio telescopes for patterns that might indicate intelligent activity.

Citizen scientists have much to offer to real science. It was almost a year ago that amateur astronomer Anthony Wesley discovered a new spot on Jupiter that had scientists pointing their telescopes in a new direction. Today, Hubble announced the cause of the spot: an asteroid.

One researcher has looked for clues to solar weather in the meridional flow, which moves from the solar equator toward the poles, and which seems to change speed during the shifting solar cycle. Another looked at the solar “jet stream,” a slow current that originates at solar midlatitudes and pushes in a bifurcated stream toward both the equator and the poles. Another scientist examined the inner workings of the sun through the oscillation of sound waves propagating through the solar interior; yet another looked at magnetic maps to chart the shifting flux across the sun.

(This quote is thanks to Scientific American.)

In other words, we still have a lot to learn about our very own star.

In fact, in 1997, NASA’S Solar and Heliospheric Observatory (SOHO) imaged the eruption of an active region on the surface of the Sun that resulted in a coronal mass ejection (CME).

Such an eruption is a gigantic belch of charged particles and radiation that, when they reach Earth, can cause disruptions in radio transmission, power outages, and luminous atmospheric displays known as the auroras.

At the same time, SOHO also captured what looked like a shock wave that radiated out from the eruption along the Sun’s surface, like a tsunami.  Solar scientists weren’t quite sure what this apparent “solar tsunami” was – were they witnessing actual wave propagation or just seeing the shadow of the ejected material?

None of SOHO’s subsequent images shed enough light on the phenomenon to answer the question, but last fall, the twin spacecraft of NASA’s Solar Terrestrial Relations Observatory (STEREO) imaged a solar eruption from two different angles simultaneously, establishing that what was observed in 1997 was indeed a shock wave that interacted with other features on the Sun – in one instance causing a solar prominence to wave like a flag in the wind.

Studies of this “fast-mode magnetohydrodynamical waves,” as they’re now known, indicate that they tower above the surrounding surface to a height more than a half-dozen times Earth’s diameter, rippling outward at half a million miles per hour.  Analysis of the behavior of these waves can help determine the structure of the Sun’s lower atmosphere and pinpoint the exact location of the solar flares that emit CMEs.  Knowing that, scientists are better able to tell whether or not CMEs may be aimed toward Earth and anticipate any effects from them.

Image: A solar tsunami seen by the STEREO spacecraft