Eclipse experiments designed to exploit the Moon’s shadow as it slides across the Earth

Monday’s solar eclipse will be exciting, strange, and possibly cause all kinds of tumult and chaos, which is pretty impressive considering it’s technically just a big shadow sweeping across the Earth. For all of the hype and hoopla, the upcoming total eclipse does offer some unusual opportunities for actual scientific research. Researchers have many experiments planned for the Moon’s shadow, many of which don’t even relate to the Moon itself. Instead, they’re looking at the Earth, Mars, Mercury and the composition of the Sun.

Earth’s atmosphere

One of the larger-scale studies planned for the eclipse will look at how a lack of sunlight changes the Earth’s ionosphere. This layer of atmosphere is normally bombarded with ions from the Sun, protecting those of us on the surface of the planet while also setting off the colorful auroras we call the Northern and Southern Lights. During the eclipse, the Moon will be intercepting those ions, and so volunteers will be measuring how this brief drop in activity affects radio wave transmissions through an unusually calm ionosphere.

Mimicking Mars

Another experiment planned for Monday involves releasing 50 high-altitude balloons into the Moon’s shadow so that we can see how a few moments in the stratosphere affects bacteria. Alongside each balloon is a metal plate swabbed with Paenibacillus xerothermodurans bacteria, which are noted for their incredible durability in harsh environments. Since it’s hard to ensure spacecraft are completely sterile before they arrive at another planet, researchers want to see how these bacteria might hold up in tough environments. The stratosphere’s thinner air, low temperatures and higher radiation levels are already a good proxy for other worlds, but during the eclipse these attributes will all be shifted to a point that closely resembles the surface of Mars. So once the balloons are recovered, researchers will get a chance to see how P. xerothermodurans might hold up on the Red Planet.

Measuring Mercury

Looking a bit deeper into space, there are plans to take advantage of the blocked sunlight to get a better look at the planet Mercury. Mercury’s proximity to the Sun makes it hard to measure, as the light and radiation levels are somewhat overwhelming for most instruments. So when the Moon makes things a bit darker, scientists plan to measure the changes in temperature around Mercury from special airplanes fitted with sensors. These planes will fly in the path of totality, or where the Moon completely blocks the Sun, in order to have more than the two minutes and 40 seconds anyone on the ground could hope for. They’ll also be flying at high altitudes to help bypass distortion that might be introduced by the Earth’s atmosphere.

Studying the Sun

Finally, at least one study will be looking at the Sun itself, which seems appropriate considering the nature of this event. Actually, scientists will be gathering data on the Sun’s corona— the wispy outer layers of plasma that will be visible during totality. As with the study of Mercury, instruments mounted on special aircraft flying at over 470 miles per hour will collect data for around six minutes to try to figure out how the Sun’s outer layers are composed, and why they’re hotter than the inner layers of the Sun. Previous measurements have found that the outer layers of the sun are hotter than most models would expect, and researchers how that this new data will help explain how that’s possible.

And of course, if anything is inclusive, we can all try again during the next total eclipse, which is only three years away if you can make the trip to Chile.

Source: Solar Eclipse-Chasing Jets Aim to Solve Mystery of Sun's Corona by Tom Metcalfe, Live Science