There is a total solar eclipse on August 21, 2017. It will last less than two and half minutes. The team of NASA-funded scientists in two retrofitted WB-57F jet planes will chase and study this eclipse.
Taking observations from twin telescopes mounted on the noses of the planes, scientists will capture the clearest images of the Sun’s outer atmosphere — the corona — to date and the first-ever thermal images of Mercury, revealing how temperature varies across the planet’s surface.
The total solar eclipse provides a rare opportunity for scientists to study the Sun, particularly its atmosphere. As the Moon completely covers the Sun and perfectly blocks its light during an eclipse, the typically faint corona is easily seen against the dark sky.
NASA is funding 11 science projects across America for scientists to take advantage of the unique astronomical event to learn more about the Sun and its effects on Earth’s upper atmosphere.
The corona is heated to millions of degrees, yet the lower atmospheric layers like the photosphere — the visible surface of the Sun — are only heated to a few thousand degrees. Scientists aren’t sure how this inversion happens.
One theory proposes that magnetic waves called Alfvén waves steadily convey energy into the Sun’s outer atmosphere, where it is then dissipated as heat. Alternatively, micro explosions, termed nanoflares — too small and frequent to detect individually, but with a large collective effect — might release heat into the corona.
Due to technological limitations, no one has yet directly seen nanoflares, but the high-resolution and high-speed images to be taken from the WB-57F jets might reveal their effects on the corona.
The high-definition pictures, captured 30 times per second, will be analyzed for wave motion in the corona to see if waves move towards or away from the surface of the Sun, and with what strengths and sizes.
Images of the Sun will primarily be captured at visible light wavelengths, specifically the green light given off by highly ionized iron, superheated by the corona. This light is best for showing the fine structures in the Sun’s outer atmosphere. These images are complementary to space-based telescopes, like NASA’s Solar Dynamics Observatory, which takes images primarily in ultraviolet light and does not have the capacity for the high-speed imagery that can be captured aboard the WB-57F.
Observations of Mercury will also be taken a half-hour before and after totality, when the sky is still relatively dark. These images, taken in the infrared, will be the first attempt to map the variation of temperature across the surface of the planet.
Mercury rotates much slower than Earth — one Mercurial day is approximately 59 Earth days — so the night side cools to a few hundred degrees below zero while the dayside bakes at a toasty 800 F. The images will show how quickly the surface cools, allowing scientists to know what the soil is made of and how dense it is. These results will give scientists insight into how Mercury and other rocky planets may have formed.
The images of the corona will also allow the team to search for a hypothesized family of asteroids called vulcanoids. Its thought these objects orbit between the Sun and Mercury, and are leftover from the formation of the solar system. If discovered, vulcanoids could change what scientists understand about planet formation.