NASA’s Solar Dynamics Observatory has observed a magnetic explosion the likes of which have never been seen before. In the scorching upper reaches of the Sun’s atmosphere, a prominence—a large loop of material launched by an eruption on the solar surface—started falling back to the surface of the Sun. But before it could make it, the prominence ran into a snarl of magnetic field lines, sparking a magnetic explosion.
Scientists have previously seen the explosive snap and realignment of tangled magnetic field lines on the Sun—a process known as magnetic reconnection—but never one that had been triggered by a nearby eruption. The observation, which confirms a decade-old theory, may help scientists understand a key mystery about the Sun’s atmosphere, better predict space weather, and may also lead to breakthroughs in the controlled fusion and lab plasma experiments.
“This was the first observation of an external driver of magnetic reconnection,” said Abhishek Srivastava, solar scientist at Indian Institute of Technology (BHU), in Varanasi, India. “This could be very useful for understanding other systems. For example, Earth’s and planetary magnetospheres, other magnetized plasma sources, including experiments at laboratory scales where plasma is highly diffusive and very hard to control.”
Previously a type of magnetic reconnection known as spontaneous reconnection has been seen, both on the Sun and around Earth. But this new explosion-driven type—called forced reconnection—had never been seen directly, thought it was first theorized 15 years ago. The new observations have just been published in the Astrophysical Journal.
The previously-observed spontaneous reconnection requires a region with just the right conditions—such as having a thin sheet of ionized gas, or plasma, that only weakly conducts electric current—in order to occur. The new type, forced reconnection, can happen in a wider range of places, such as in plasma that has even lower resistance to conducting an electric current. However, it can only occur if there is some type of eruption to trigger it. The eruption squeezes the plasma and magnetic fields, causing them to reconnect.
While the Sun’s jumble of magnetic field lines are invisible, they nonetheless affect the material around them—a soup of ultra-hot charged particles known as plasma. The scientists were able to study this plasma using observations from NASA’s Solar Dynamics Observatory, or SDO, looking specifically at a wavelength of light showing particles heated 1-2 million kelvins (1.8-3.6 million F).
The observations allowed them to directly see the forced reconnection event for the first time in the solar corona—the Sun’s uppermost atmospheric layer. In a series of images taken over an hour, a prominence in the corona could be seen falling back into the photosphere. En route, the prominence ran into a snarl of magnetic field lines, causing them to reconnect in a distinct X shape.
Spontaneous reconnection offers one explanation for how hot the solar atmosphere is—mysteriously, the corona is millions of degrees hotter than lower atmospheric layers, a conundrum that has led solar scientists for decades to search for what mechanism is driving that heat. The scientists looked at multiple ultraviolet wavelengths to calculate the temperature of the plasma during and following the reconnection event. The data showed that the prominence, which was fairly cool relative to the blistering corona, gained heat after the event. This suggests forced reconnection might be one way the corona is heated locally. Spontaneous reconnection also can heat plasma, but forced reconnection seems to be a much more effective heater—raising the temperature of the plasma quicker, higher, and in a more controlled manner.
While a prominence was the driver behind this reconnection event, other solar eruptions like flares and coronal mass ejections, could also cause forced reconnection. Since these eruptions drive space weather—the bursts of solar radiation that can damage satellites around Earth—understanding forced reconnection can help modelers better predict when disruptive high-energy charged particles might come speeding at Earth.
Understanding how magnetic reconnection can be forced in a controlled way may also help plasma physicists reproduce reconnection in the lab. This is ultimately useful in the field of laboratory plasma to control and stabilize them.
The scientists are continuing to look for more forced reconnection events. With more observations they can begin to understand the mechanics behind the reconnection and often it might happen.
“Our thought is that forced reconnection is everywhere,” Srivastava said. “But we have to continue to observe it, to quantify it, if we want prove that.”
SDO sees new kind of magnetic explosion on sun (2019, December 17)
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Manitoba company helps land Perseverance rover on Mars with high-speed camera – CBC.ca
It’s only about the size of a loaf of bread. But a high-speed, tough-as-nails camera created by a company in Minnedosa, Man., played an instrumental role in landing NASA’s Perseverance rover on Mars last week.
“You could run over it, it could fall, you could throw it out your window. That’s how tough they need to be,” Canadian Photonic Labs president Mark Wahoski said of the camera used in the monumental landing on Feb. 18.
His company, based in the southwestern Manitoba town — population around 2,500 — manufactures high-speed cameras for industrial, scientific and military markets, according to its website.
It took years to design the Perseverance camera in a way that would allow it to withstand the planet’s gravitational force — and snap images fast enough, Wahoski told host Marjorie Dowhos on CBC’s Radio Noon on Friday.
“It’s really hard to comprehend just how fast that is,” he said. “They go anywhere from normal, 30 frames per second — like your cellphone camera — all the way up to 250,000 frames per second.”
And the testing involved to make sure it’s up to the task before it gets sent into space is just as complex.
One of the simulations involved sending a metal sled with rocket engines strapped on top of it down a five-mile railroad bed in California, Wahoski said.
Another saw a helicopter lift a parachute, tied to that same rocket sled, up thousands of feet in the air before sending the sled down the track.
“On one of the tests, they determined they had to make this particular part stronger. So without those tests, the lander probably would not make it,” Wahoski said.
The Manitoba company’s relationship with NASA dates back roughly 15 years, he said — but much of the work that’s happened in that time has been cloaked in secrecy.
“A lot of it you can’t speak about…. You do the test and you do the support and you move on to the next project,” he said.
However, the attention around the Perseverance rover landing has been an exciting development, Wahoski said.
Once the landing finally happened, he said he had one word to describe how he felt: awesome.
“We had to just reflect back and say, ‘Oh gee, yeah, we did some of that.'”
NASA's Perseverance Rover Transmits to Earth from the Surface of Mars – UPI.com
NASA’s Mars Perseverance rover acquired this image during its descent to Mars, using its Descent Stage Down-Look Camera. This camera is mounted on the bottom of the descent stage and looks at the rover. This image was acquired on February 22, 2021 (Sol 1) at the local mean solar time of 10:37:31. A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, paving the way for human exploration of the Red Planet and be the first mission to collect and cache Martian rock and regolith. NASA/UPI
SEE IT: moon-sized fireball shot through sky over Chatham-Kent – Chatham Daily News
Stargazers were treated to quite the show on Friday night with a giant fireball spotted in Chatham-Kent.
Peter Brown, Western University professor in the astronomy and physics department, posted on Twitter on Saturday morning that the fireball ended at approximately 30 km in height just north of Lake St. Clair near Fair Haven, Mich.
According to the NASA website, observers in Ontario, Michigan, New York, Ohio and Pennsylvania reported the sighting at 10:07 p.m. EST.
“This event was captured by several all sky meteor cameras belonging to the NASA All Sky Fireball Network and the Southern Ontario Meteor Network operated by Western University,” it stated.
“A first analysis of the video data shows that the meteor appeared 90 km (56 miles) above Erieau on the northern shore of Lake Erie. It moved northwest at a speed of 105,800 kilometres per hour (65,800 miles per hour), crossing the U.S./Canada border before ablating 32 kilometres (20 miles) above Fair Haven, Mich.”
NASA stated the orbit of the object is “low inclination” and has an aphelion — defined as the point in the orbit of an object where it is farthest from the sun — near the orbit of Jupiter, and a perihelion — nearest to the sun — between the orbits of Mercury and Venus.
“It suggests that the meteor was caused by a fragment of a Jupiter family comet, though an asteroidal origin is also possible. At its brightest, the fireball rivalled the quarter moon in intensity. Combining this with the speed gives the fragment a mass of at least two kilograms and a diameter of approximately 12 centimetres (five inches).
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