Researchers have discovered the our planet’s atmosphere regularly expands and contracts in a short cycle of about nine days, and say that this “breathing” is caused by powerful gusts of solar wind. While researchers already knew that ultraviolet light from the sun can heat and swell the atmosphere, the discovery of short, cyclical fluctuations “was a surprising finding” that wasn’t correlated with any variation in solar UV flux [Science News], says atmospheric scientist Jeffrey Thayer.
The breathing cycle seems to reach its peak when solar features called coronal holes are facing Earth. These dark spots in the sun’s corona—a sort of solar atmosphere—are areas where the sun’s magnetic field has been blown open by pressurized solar wind, sending the “winds” toward Earth at high speed. As the fast winds streaming from coronal holes approach Earth, they cause gases in our upper atmosphere to heat up and expand, then cool down and contract, changing the upper atmosphere’s density [National Geographic News].
(more…)
The magnetic field that surrounds our planet and protects us from the sun’s harmful radiation sometimes springs a couple of large leaks that let in blasts of solar wind, researchers have discovered. While humanity isn’t in any imminent danger, researchers say that during intense solar storms the rents in what’s known as the magnetosphere will let in streams of charged solar particles, which can interfere with satellites and electricity grids.
Researchers knew previously that cracks in the magnetosphere sometimes occur, but they didn’t understand their potential size and had some misunderstandings about how they formed. Previously, scientists believed that the holes form when the sun’s magnetic field is aligned in the opposite direction from the Earth’s. But the new study showed that 20 times more solar particles enter the Earth’s magnetic field when it is aligned in the same direction as the sun’s magnetic field. The alignment causes the two magnetic fields to connect and tears holes in the Earth’s magnetic field over the poles. “What we observed was the breach in the levee,” said Jimmy Raeder, a physicist at the University of New Hampshire. “This has taken us completely by surprise” [Reuters].
(more…)
Researchers have tested a small, portable magnetic field that could be just the protection required for a manned expedition to Mars, when astronauts would need to be protected from radiation from solar storms. Researchers say the lab experiment is the proof of concept for a magnetic force-field that mimics the protective qualities of the Earth’s magnetosphere, which shields our planet from that same radiation.
Outside Earth’s protective atmosphere and magnetic field, supersonic particles from stellar processes run amok, screaming through space and tearing through just about anything in their path—including the bodies of astronauts, where they can wreak havoc on genetic material [Scientific American]. Astronauts on the International Space Station are within Earth’s protective magnetic field, so the Apollo astronauts who went to the moon are the only humans who have been exposed to this radiation; happily, there were no major solar storms during their quick trips to the moon and back. However, a manned mission to Mars would take about six months each way, leaving astronauts much more vulnerable.
(more…)
On Sunday, a small space probe with a big mission took off from Earth in a flawless launch, setting off on a two-year assignment to map the edge of our solar system. The Interstellar Boundary Explorer soared into space aboard an Orbital Space Sciences Pegasus rocket that fired as planned at 12:48 p.m. CDT, moments after dropping from the belly of a modified airliner that flew across the South Pacific near Kwajalein Atoll [San Antonio Express-News].
The $169 million NASA probe will settle into a long, elliptical orbit around Earth that takes it beyond the interference of our planet’s magnetosphere, and almost as far as the moon. From there the IBEX will record the impacts of particles that are formed at the edge of our solar system’s protected space, a region known as the heliosphere. The solar wind, a stream of charged particles spewing from the sun at 1 million miles per hour, carves out a protective bubble around the solar system. This bubble … shields against most dangerous cosmic radiation that would otherwise interfere with human spaceflight [AP]. At the edge of the heliosphere, the solar wind slows down as it slams into interstellar space; IBEX will observe the particles created in this “termination shock” to chart the solar system’s perimeter.
(more…)
On October 19, NASA will launch the small Interstellar Boundary Explorer (IBEX) into orbit on a mission to map the turbulent edge of our solar system, where the solar wind slams into interstellar space. While it won’t actually travel beyond all the planets to investigate the solar system’s far reaches, the coffee table-sized spacecraft must escape the area where Earth’s magnetic field reigns, which could interfere with its measurements. The $169 million observatory is due to climb 200,000 miles (322,000 kilometers) above Earth and settle into orbit there for a mission of at least two years. For comparison, the moon orbits about 240,000 miles (385,000 km) from Earth [SPACE.com].
The edge of the solar system is currently being explored directly by the Voyager 1 and Voyager 2 spacecrafts; both Voyagers launched 31 years ago and recently passed the point where the solar wind is slowed by interactions with the interstellar plasma, a point known as the termination shock. These crafts “are making fascinating observations of the local conditions at two points beyond the termination shock that show totally unexpected results and challenge many of our notions,” said [IBEX researcher David] McComas [World Science].
(more…)
The solar wind, a steady stream of charged subatomic particles that stream out from the sun at a speed of one million miles per hour, has dwindled to its weakest state since recording began, researchers say. While researchers already knew that solar winds fluctuate in 11-year cycles, the current doldrums trump the declines seen over the past 50 years. “We know that the sun has been this cool before, this inactive before,” said [physicist] Nancy Crooker…. “But that was prior to the Space Age, so we didn’t have actual physical measurements until now” [SPACE.com].
The data was collected by the first solar explorer, the Ulysses probe, which was launched in 1990 as a joint venture between NASA and the European Space Agency. The 17-year-old space probe, which circles the sun from a distance of about 337 million miles, has been studying the environment above and below the poles of the sun. It is just months away from shutting down because of freezing fuel [AP].
(more…)
A remarkable stellar event that mesmerized astronomers in 1843 may have been a previously unknown kind of explosion, researchers say. That explosion, which made the star Eta Carinae one of the brightest in the Southern sky, could have been the precursor to the star’s expected explosion into a supernova.
Researchers began watching Eta Carinae after the star mysteriously brightened 1843, and astronomers in recent decades have photographed and studied the resulting cloud of gas and dust, known as the Homunculus Nebula, that billows away from the star. A farther-out faint shell of debris from an earlier explosion is also visible, probably dating from around 1,000 years ago. “Looking at other galaxies, astronomers have seen stars like Eta Carinae that get brighter, but not quite as bright as a real supernova,” said [lead researcher] Nathan Smith…. “We don’t know what they are. It’s an enduring mystery as to what can brighten a star that much without destroying it completely” [SPACE.com].
(more…)
The exact mechanism that triggers the colorful auroras that dance across the night sky near the Earth’s two poles has been revealed by a quintet of NASA satellites. Scientists already knew that disturbances in the Earth’s magnetic field, called “substorms,” bring charged particles into the Earth’s upper atmosphere, where they collide with gas particles. Those gas particles then release energy as light, which flickers across the sky in waves of greens, reds, and blues.
Now, researchers with NASA’s THEMIS mission say they’ve discovered what sets off those magnetic disturbances. The substorms begin far out in space, roughly a third of the way to the Moon, where magnetic fields from the Earth are thrown together and reconnect to sling charged particles back toward the planet, they say [New Scientist].
(more…)
When the private space company SpaceX launches its Falcon 1 rocket at the end of July, it will bring an intriguing experiment into orbit: a small NASA satellite that could be maneuvered through space with an attached “solar sail.” The sail would be powered by photons from the sun hitting the reflective surface, a series of tiny impacts that can provide a boost in the frictionless void of space.
In a video, NASA scientists show off a satellite about the size and shape of a shoebox with four masts that spring out to support the sail, which measures 100 square feet when unfurled. If the sail is successfully deployed, NASA will experiment with using the sail to control the satellite’s altitude and orbital maneuvering.
To understand this technology’s potential, consider that it took the Voyager probes 30 years to get to the edge of the solar system where they are still hurtling outward further every day. Although slower to get started, a solar sail could catch up with a Voyager spacecraft in a single decade [Wired News].
(more…)
