Astronomers Prepare for a Total View of Total Solar Eclipses

A team of astronomers have proposed a series of missions utilizing land, sea, and airborne observatories to continuously monitor as many total solar eclipses as possible in the coming decade. These missions will reveal aspects of the solar corona that cannot be studied by any other means.

The space age brought a revolution in understanding the nature of the Sun. With the capability to place an observatory in orbit we could continuously monitor solar activity. The development of the coronagraph, which is a small disk placed in front of a telescope that blocks out the light from the surface of the Sun itself, also allowed observatories to study the corona. The corona of the Sun is the hot, thin atmosphere that extends out to twice the solar radius. 

The corona has a temperature of over a million degrees Kelvin, despite the surface of the Sun having a temperature of only around 10,000 Kelvin. Despite decades of intense research, we still do not fully understand how the corona reaches such incredibly high temperature, especially considering its low density and its distance from the Sun. Space-based observatories are able to map extensive regions of the corona, but they have difficulty observing continuous regions out past 50% greater than the Sun’s radius. Their limited field of view prevents them from having a complete picture.

The only way to develop a complete picture of the entire solar corona is to use a natural coronagraph, which happens with every total solar eclipse. During a total solar eclipse, the disk of the Moon blocks out that of the Sun, making the corona visible. Ground-based observatories have an advantage here over space-based ones because they can enjoy a much greater field of view.

The downside is that total solar eclipses do not last long and happen all over the globe. To counteract this, a team of astronomers have proposed a call for funding to support a series of total solar eclipse observations. They hope to use mobile ground-based observatories, observatories on ocean-going vessels, and telescopes in aircraft to capture as many coming total solar eclipses as possible.

They hope that their observations will reveal a better, more coherent picture of corona activity, especially its emission spectrum in visible and near-infrared wavelengths. This can reveal critical information as to the components of the solar corona and their energies. This can feed into other observations of the solar corona to put together a complete picture and help untangle its many mysteries.