Millions of people across the continental US will record images of today’s total eclipse on digital devices, making this the most recorded event in history. A few decades ago they would have used film cameras and a few hundred or thousand years ago observers would have drawn or painted what they saw on paper, bark, hides or on pottery or they would have pecked and painted the images on rock outcrops.
The first photographs of a total eclipse were taken in the mid-19th century. The technical difficulties, then as now, are that the sun is very small and bright — with an angular diameter of just .5° — the inner corona is bright and the outer corona dim. Consequently it is difficult to take a single photo that provides a good representation of both the inner and outer corona — as one or the other is either over exposed or under exposed.
Modern eclipse photographers like Miloslav Druckmüller solve those problems with massive telephoto lenses and post processing of the images — combining multiple exposures www.zam.fme.vutbr.cz/…
The vast majority of us don’t have the skill, knowledge or equipment to take great eclipse photos — so I’d recommend that you focus on the crowd and scenery around you or just watch during the event and leave the attempts at close up corona photos to the pros like Druckmüller.
Images of the corona appear in early classical art — in association with Helios the Greek god of the sun. The corona observed during total eclipses appears to be the source of many common and widespread spread symbols including the Egyptian winged eye and the cross in circle and the ogee.
By the 4th Century A.D. the corona appears in artistic representations of Jesus — in the form of the halo we now associate with holiness.
The shape of the sun’s corona is determined by the sun’s magnetic field which is highly variable — every 11 years or so the magnetic poles of the sun reverse — so the magnetic north pole migrates to the south pole — and after another 11 years later returns to its former position.
The intensity of the magnetic field is evident by sunspot activity — so during periods of high sunspot numbers we see symmetrical coronal forms and during periods of low magnetic activity and low sunspots — like now — the corona is more asymmetrical. This relationship between coronal form and sunspot activity was first recognized by western science in 1879 by A. C. Ranyard who compiled scientific illustrations of total eclipses observed during the previous 150 years (books.google.com/...}
A variety of what appear to be eclipse images survive in ancient rock art around the world. Some of that rock art is found along or near the path of today’s solar eclipse — here are a few examples.
Compare the corona observed on Feb. 9, 1766 with that pecked into rock in the Columbia River gorge — from a much earlier but similar solar eclipse.
The corona this year is likely to be more asymmetrical since the sun is now in a period of very low magnetic activity and declining sunspots. The typical coronal form associated with this condition — should be similar to that photographed by Druckmuller in 1995 in India and that recorded by prehistoric Indians along the Mississippi River at a rock shelter on Fountain Bluff.
If skies are clear today at 1pm along the Mississippi — observers at that site should be able to see a coronal form today similar to that pecked into the rock there centuries ago.
Looking cloudy now in my backyard, but hoping for skies to clear by eclipse time. I