NASA's science during the March 2016 total solar eclipse

March 4, 2016
Outside of total solar eclipses, scientists use an instrument called a coronagraph to see the sun’s tenuous atmosphere. Because of how light bends around sharp edges coronagraphs block this extra light by blocking part of the inner corona. In this coronagraph image, the white circle outlines the extent of the solar surface, showing how much of the sun's atmosphere is blocked by the coronagraph’s disk. Credit: NASA/SOHO

As the moon slowly covers the face of the sun on the morning of March 9, 2016, in Indonesia, a team of NASA scientists will be anxiously awaiting the start of totality – because at that moment, their countdown clock begins. They plan to take 59 several-second exposures of the sun in just over three minutes, capturing data on the innermost parts of the sun's volatile, superhot atmosphere – a region we can only observe during total solar eclipses when the sun's overwhelmingly bright face is completely blocked by the moon.

"The 's atmosphere is where the interesting physics is," said Nelson Reginald, one of several space scientists from NASA's Goddard Space Flight Center in Greenbelt, Maryland, who will conduct an experiment in Indonesia during March 2016's total solar eclipse. "A total solar eclipse gives us the opportunity to see very close to the solar limb."

The lower part of the sun's atmosphere, the corona, is one of the most scientifically interesting areas of the sun. It's thought to hold the keys to several solar mysteries, from the acceleration of the solar wind, to the birth of explosive clouds of solar material called , to the mysterious heating of the corona as a whole. Using a new instrument, the NASA science team will observe aspects of polarized light that carry information about the temperature and velocity of electrons in the lower corona.

Though it's about as bright as the full moon, the corona is ordinarily drowned out by the sun's much brighter face, except during total solar eclipses. To study the corona outside of total solar eclipses, scientists use instruments called coronagraphs, which create artificial eclipses by using solid disks to block sun's bright face and reveal the comparatively faint corona. But because light bends around sharp edges – a phenomenon known as diffraction – coronagraph disks obscure the inner corona, as well as the solar surface, to combat this effect.

The video will load shortly
Scientists from NASA Goddard explain the experiment they will perform in Indonesia during the March 2016 total solar eclipse. During the brief period of totality, the team will use a new instrument to measure polarized light from the sun’s faint atmosphere, the corona, in order to study the temperature and speed of electrons. Credit: NASA’s Goddard Space Flight Center/Duberstein

"You can't see the corona that close to the surface with a coronagraph. You cut off a large portion of the innermost corona," said Nat Gopalswamy, principal investigator of the eclipse experiment at Goddard. "The main advantage of the total solar eclipse is seeing much closer to the sun's surface."

The team will use their three minutes of totality to examine the polarized light coming from the sun's inner corona, light that contains information about the temperature and velocity of the electrons there. Light is polarized when its electric field oscillates along one axis, for instance, up-and-down or side-to-side. Unlike dust, electrons mainly scatter polarized light, meaning that isolating the can give information about the temperature and flow speed of coronal electrons. Polarized light scattered by these electrons dominates in the regions of the corona closest to the solar surface – so total solar eclipses are our best chance to gather this information.

"We first used this instrument during the 1999 total solar eclipse in Turkey," said Reginald.

The minutes-long timeframe of total solar eclipses limits the amount of data we can collect during our occasional glimpses at the inner corona, so the team rebuilt their instrument over the last year to make it even faster.

"Before, we would have had use a polarizer that would turn through three angles for each wavelength filter," said Reginald. "The new polarization camera eliminates the need for a polarization wheel."

Rather than using a hand-turned polarization wheel to take three separate images in each polarized direction, the new camera uses thousands of tiny polarization filters to read light polarized in different directions simultaneously. Each pixel in the new camera is made of four subpixels with differently-oriented polarization filters, which provides the team with four separate but simultaneous images of the and cuts out the need to change polarization filters between exposures.

"We've cut down the length of time required for our experiment by more than 50 percent," said Gopalswamy. "The polarization camera is faster and less risky, because it's one less moving part."

Though the team will be performing the experiment for the first time in the province of North Maluku, Indonesia – chosen for its accessibility and high chances of clear skies during the eclipse – they've already given their updated instrument a test run.

"The brightness of the full moon is about equal to the brightness of the ," said Reginald. "So we set up our telescope in the parking lot for practice."

Explore further: Image: Proba-2 captures partial solar eclipse

Related Stories

Image: Proba-2 captures partial solar eclipse

September 16, 2015

ESA's Sun-watching Proba-2 satellite experienced three partial solar eclipses on 13 September 2015. On Earth, a single partial eclipse occurred over South Africa, the southern Indian Ocean and Antarctica.

Prepare for a total solar eclipse

November 13, 2012

(—Tomorrow's total solar eclipse will only be visible in its entirety to ground-based observers watching from northern Australia, but ESA's Sun-watching Proba-2 satellite will have a ringside seat from its orbit ...

Total solar eclipse viewed from Australia

November 14, 2012

On Nov. 13, 2012, a narrow corridor in the southern hemisphere experienced a total solar eclipse. The corridor lay mostly over the ocean but also cut across the northern tip of Australia where both professional and amateur ...

Image: Eclipse season begins for NASA's SDO

March 1, 2016

The 2016 spring eclipse season of NASA's Solar Dynamics Observatory began Feb. 19, 2016. These seasons – a time when Earth blocks SDO's view of the sun for a period of time each day – last around three weeks and happen ...

Hinode to support ground-based eclipse observations

November 13, 2012

(—On Nov. 13, 2012, certain parts of Earth will experience a total solar eclipse, which, like all eclipses, will only be visible when you are aligned in a straight line with the moon and the sun. In this case the ...

Recommended for you

Gaia spies two temporarily magnified stars

October 28, 2016

While scanning the sky to measure the position of over one billion stars in our Galaxy, ESA's Gaia satellite has detected two rare instances of stars whose light was temporarily boosted by other celestial objects passing ...

How planets like Jupiter form

October 28, 2016

Young giant planets are born from gas and dust. Researchers of ETH Zürich and the Universities of Zürich and Bern simulated different scenarios relying on the computing power of the Swiss National Supercomputing Centre ...

More than 15,000 near-Earth objects and counting

October 28, 2016

The international effort to find, confirm and catalogue the multitude of asteroids that pose a threat to our planet has reached a milestone: 15 000 discovered – with many more to go.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.