Staring at the Sun: NASA takes incredible solar portrait

A NASA telescope designed to probe black holes and the vast expanses of the cosmos has set its sights on the burning heart of our own solar system, capturing the sun in all its high-energy x-ray glory.

The picture is the first image of the sun captured using NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR.
While the sun is far too bright for other NASA telescopes to gaze at without risking damage to their detectors, NuSTAR’s high end optics – designed to focus X-rays – were more than up to the task.

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According to the agency, solar scientists had first considered using NuSTAR to study the sun around seven years ago, while it was still under construction. Fiona Harrison of the California Institute of Technology in Pasadena was initially skeptical of the idea.

"At first I thought the whole idea was crazy," said Harrison. "Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?"

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She soon warmed to the proposition, however, after David Smith, a solar physicist and member of the NuSTAR team at University of California, Santa Cruz, told her that faint X-ray flashes predicted by theorists could only be seen by NuSTAR.

Sun shines in high-energy X-rays in our new cover image, the first ever @NASANuSTAR sun pic: http://t.co/5WmrI9DSuTpic.twitter.com/GMijvI3qHv

— NASA (@NASA) December 22, 2014

NuSTAR managed to do just that, capturing those faint x-ray emissions of the sun, depicted in green and blue in the photograph above. The reddish-orange, swirling mass of hot plasma, meanwhile, is an ultraviolet image by NASA’s Solar Dynamics Observatory. A composite image of the two pictures provides a visually stunning portrayal of the sun’s hot spots.

In fact, it is the high temperatures registered above sunspots – the dark patches on the sun’s photosphere – which are of particular interest to the scientists. With the sun’s winds expected to calm down in the current solar cycle, scientists hope to capture hypothesized nanoflares – smaller versions of the massive solar flares – which spew out clouds of electrons, ions, and atoms through the outer atmosphere of the sun (corona) into space.

Holiday lights on the sun! A significant solar flare erupted on Dec 19: [video] http://t.co/J1dk3nZURB@NASASunEarthpic.twitter.com/dnQkCyy8Kk

— NASA (@NASA) December 22, 2014

Scientists believe nanoflares could help explain why the corona is drastically hotter than the surface of the sun, a mystery called the “coronal heating problem.”

According to NASA, the corona is, on average, 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the surface of the sun is relatively cooler at 10,800 Fahrenheit (6,000 degrees Celsius). The agency likens the coronal activity to flames coming out of an ice cube. They have theorized that flares and nanoflares may be responsible for the intense heat. If NUSTAR manages to catch these elusive nanofalres in action, it could solve a decades-long problem in solar physics.

Apart from shedding light on the center of our own solar system, NASA also believes NuSTAR could potentially detect hypothesized dark matter particles called axions. If they exist, axions would appear as a spot of X-rays in the center of the sun.

While it remains a longshot, just the chance of learning more about dark matter, which is theorized to make up most of the universe, is certainly a boon to scientists. Ironically, they just might discover something new under the sun by staring directly at it.