During a total solar eclipse, there is this brief, roughly 1-20 seconds during which some absolutely incredible, indescribable phenomenon occurs. It was the most beautiful thing I have ever seen. They are referred to as Bailey’s beads and the diamond ring effect. I was wondering at which magnitude this phenomenon occurs? The eclipse magnitude measures how much of the sun is covered by the moon. For example, a magnitude 0 means none of the sun is covered. In a 0.5 magnitude, 50% of the sun would be covered. In a magnitude 1, the sun is perfectly covered. Just looking at NASA’s 5 Millennium Canon of Solar Eclipses, the lowest magnitude in the 5,000 years surveyed was one in 1838 B.C. which had a 0 magnitude. I have no idea how that counts as an eclipse. The highest magnitude was that of one from 504 A.D. with a magnitude of 1.0813. As for as those close to 1, there is one eclipse with a magnitude of 0.9998, six eclipses at 0.9999, three at 1, seven are at 1.0001, and eight are at 1.0002.

For the three with a magnitude of 1, the first occurs in 1804, the second in 1986, and the third in 2931. The first two are hybrid, while the last is annular. On a side note, how can a magnitude of 1 not be total? All three interestingly have a central duration of 0, so I really am confused, but maybe that requires other questions. Anyways, so people witnessing these eclipses, would they basically ONLY see the Bailey’s Beads phenomenon? For this question, I just want to know what percent of the sun needs to be covered for these two phenomena to occur? When it started for me, I was entirely unable to see the sun with my ND5 glasses when the ring effect happened.

So, the question is, what magnitude of eclipse does the diamond ring effect start to occur? Does it start at magnitude 1? 0.9995? 1.0005? Where?

I know I shouldn’t do this, but if you’re on this site, looking at this question, TRUST ME, you want to make EVERY effort to see a total eclipse. DON’T BOTHER with a partial or annular eclipse, there’s no point. But totality is something you definitely want to see before you die.

  • $\begingroup$ The diamond ring happens at start and end of totality. So anything larger than 1 is fine $\endgroup$ Commented Apr 14 at 6:42
  • $\begingroup$ An exact answer isn't possible as it relies on the atmospheric conditions and visual abilities of the observer. E.g, on a high mountaintop, less of the sunlight will be scattered to drown out the corona, so the observer's ability see both brightness levels at the same time dominates. At lower, and lower altitudes the sunlight is scattered more by the atmosphere, and that is the effect that dominates. $\endgroup$ Commented Apr 14 at 21:25


You must log in to answer this question.

Browse other questions tagged .