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Why is the Sun’s atmosphere much hotter than its surface

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Why is the Sun's atmosphere much hotter than its surface
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Washington, Oct 14: Scientists have found that small solar flare could help explain why the Sun’s atmosphere, the corona, is so much hotter than the surface.

The corona is hundreds to thousands of times hotter than the Sun’s visible surface, the photosphere.

Because the Sun produces heat at its core, this runs counter to what one would initially expect: normally the layer closest to a source of heat, the Sun’s surface, in this case, would have a higher temperature than the more distant atmosphere.

“If you’ve got a stove and you take your hand farther away, you don’t expect to feel hotter than when you were close,” said one of the study authors Lindsay Glesener from University of Minnesota in the US.

The cause of these counterintuitively high temperatures is an outstanding question in solar physics.

One possible solution to the coronal heating problem is the constant eruption of tiny solar flares in the solar atmosphere, so small that they can not be directly detected.

In a study published in the journal Nature Astronomy this week, the scientists reported that a NASA sounding rocket instrument spotted signatures of the long-sought small solar flares.

The second flight of the FOXSI instrument – short for Focusing Optics X-ray Solar Imager – during its December 2014 flight on a suborbital sounding rocket detected a type of light called hard X-rays – whose wavelengths are much shorter than the light humans can see – which is a signature of extremely hot solar material.

These kinds of temperatures are generally produced in solar flares, powerful bursts of energy.

But in this case, there was no observable solar flare, meaning the hot material was most likely produced by a series of solar flares so small that they were undetectable from Earth: nanoflares.

“The key to this result is the sensitivity in hard X-ray measurements,” said Shin-nosuke Ishikawa, a solar physicist at the Japan Aerospace Exploration Agency, or JAXA, and lead author on the study.

“Past hard X-ray instruments could not detect quiet active regions, and combination of new technologies enables us to investigate quiet active regions by hard X-rays for the first time,” Ishikawa added.

FOXSI is a collaboration between the US and e Japan Aerospace Exploration Agency.

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NASA’s 2020 Mars rover to have 23 ‘eyes’

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NASA's 2020 Mars rover to have 23 'eyes'. Pixabay

Washington, Nov 1,2017: NASA said its Mars 2020 mission will have more “eyes” than any rover before it – a grand total of 23, to create sweeping panoramas, reveal obstacles, study the atmosphere and assist science instruments.

They will provide dramatic views during the rover’s descent to Mars and be the first to capture images of a parachute as it opens on another planet.

 There will even be a camera inside the rover’s body, which will study samples as they are stored and left on the surface for collection by a future mission, NASA said on Tuesday.

When NASA’s Mars Pathfinder touched down in 1997, it had five cameras. The subsequent Spirit and Opportunity rovers were designed with 10 cameras each, including on their landers. The Curiosity rover has 17 cameras.

“Camera technology keeps improving,” said Justin Maki of NASA’s Jet Propulsion Laboratory in Pasadena, California.

“Each successive mission is able to utilise these improvements, with better performance and lower cost,” Maki said.

The cameras on 2020 will include more colour and 3-D imaging than on Curiosity, said Jim Bell of Arizona State University.

“Routinely using 3-D images at high resolution could pay off in a big way,” Bell said. “They’re useful for both long-range and near-field science targets.”(IANS)

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