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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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Submit your name to go onboard NASA’s new solar mission

The spacecraft -- about the size of a small car -- will travel directly into the Sun's atmosphere about four million miles from the star's surface

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NASA Seeks Partnership With US Industry to Develop First Gateway Element
NASA, Pixabay
  • NASA is inviting names from all over the world
  • Now you can have your name placed on a microchip
  • This chip would be in NASA’s historic Parker Solar Probe mission

NASA is inviting people around the world to submit their names online to be placed on a microchip aboard NASA’s historic Parker Solar Probe mission, to be launched this summer.

The mission will travel through the Sun’s atmosphere, facing brutal heat and radiation conditions — and your name will go along for the ride. The submissions of names will be accepted until April 27, the US space agency said in a statement on Thursday.

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This mission will be launched to know more about sun’s atmosphere.

“This probe will journey to a region humanity has never explored before. This mission will answer questions scientists have sought to uncover for more than six decades,” said Thomas Zurbuchen, Associate Administrator for Science Mission Directorate at NASA.

The spacecraft — about the size of a small car — will travel directly into the Sun’s atmosphere about four million miles from the star’s surface. The primary goals for the mission are to trace how energy and heat move through the solar corona and to explore what accelerates the solar wind as well as solar energetic particles.

Also Read: NASA delays launch of next-gen space telescope until 2020

To perform the investigations, the spacecraft and instruments will be protected from the Sun’s heat by a 4.5-inch-thick carbon-composite shield. The state-of-the-art heat shield will keep the four instrument suites designed to study magnetic fields, plasma and energetic particles, and image the solar wind at room temperature. In May 2017, NASA renamed the spacecraft from the Solar Probe Plus to the Parker Solar Probe in honour of astrophysicist Eugene Parker. IANS