Three Space Weather Phenomena To Watch For During the 2017 Solar Eclipse

Northern Lights Now – The August 21st Great American Eclipse promises to be the most photographed eclipse on record.
Millions of people will be able to see either a partial or full eclipse just by walking outside and using their eclipse glasses to observe the Sun.

Viewers lucky enough to be in the path of totality will see the Sun as a dark circle surrounded by the bright corona. They will see familiar winter star constellations. Jupiter, Mars, Venus and Mercury will be visible.

There are three particularly interesting and exciting Phenomena that eclipse chasers may see in the coronal that are relevant to aurora hunting.


At Northern Lights Now we frequently post images from the LASCO C2 and C3 chronographs. These are images of the Sun from satellites that by simulating eclipses with a round disk is extended by an arm in front of the lens. The disk blots out the Sun allowing the camera to capture the corona. These images allow space weather scientists to see the plasma that erupts from the Sun during solar flares and filament eruptions.

CME launches off the Sun visible in LASCO
CME launches off the Sun visible in LASCO

If there is one of these Corona Mass Eruptions (CMEs) during the time of the eclipse, ground based viewers (you!) will be able to see the eruption in the corona during totality. It won’t look like the dramatic image above, because that is several hours of eruption compressed in a timelapse. You will see the equivalent of one or two frames of the timelapse during the time you are in totality. But when you share you photos on Twitter, you will be able to combine them with the images other viewers take, and together we may be able to build a time lapse of ground based eclipse imagery that may show a CME in progress.

Up until about a week ago, the chances for a CME during totality were low. The Sun is currently approaching its minimum activity of solar eruptions in the 11 year cycle. But several active sunspot regions, where these eruptions originate, have grown over the last 2-3 days. The odds of a CME during totality are still low, less than 20%, but they are high enough it is worth keeping track of the active sunspot regions as they grow.

Solar prominences on the limbs

When active filaments and solar prominences are on the limb, they are easy to see and identify because they have stark contrast with the blackness of space behind the Sun. They appear clearly in AIA 304 imagery as they float above or lift off the surface of the Sun.

A prominence lifts off the East limb in timelapse animated GIF of AIA 304 from SDO
A prominence lifts off the East limb in timelapse animated GIF of AIA 304 from SDO

Similarly, during an eclipse these features appear visibly as bright structured areas in the corona to ground based viewers. If there happen to be prominences on the limb at the time of totality, this is a treat to see.

Sun Grazing and Sun Diving Comets

Several times a month comets are pulled into the gravity of the Sun and they burn up as they fly by or crash into the Sun. Sun grazers fly by and become visible as they melt and have a tail while Sun diving comets crash into the Sun never to be seen again. Aurora hunters are familiar with these as they often show up in LASCO imagery. If there is a comet hurtling towards the Sun and it has a tail during the time of totality, it will may be visible.

Sun diving and Sun grazing comets to not have any impact on solar storms or our ability to see aurora. They are a familiar feature to aurora hunters and the eclipse provides a unique opportunity to see them during the day.

********** Eclipse viewing Warning ************

DO NOT Look at the eclipse without protection. You will burn your retinas by staring at the Sun during the eclipse. Sun Glasses are not protection. You need SO and CE certified viewing glasses to look at the sun during any phase of the eclipse that is partial. You can make a pinhole viewer to watch the eclipse if you do not have safe glasses. Please don’t end up in the hospital, please don’t end up blind.

Happy Hunting!