Explanation:
The “Diamond Ring with Clouds” over
Wuhan.
The following information is from Wikipedia:
The diamond ring is a phenomenon that occurs during a total solar eclipse. Just before the Sun is completely obscured by the Moon, or just after it emerges from behind the Moon, sunlight shining through the irregular terrain of the lunar limb creates a series of bright spots that look like pearls. This phenomenon is known as Baily’s beads, named in honor of the British astronomer Francis Baily, who first explained the phenomenon in 1836. (British astronomer Edmond Halley first reported the Baily’s beads phenomenon in 1715, and Francis Baily correctly explained it in 1836.)
The smoothness of the lunar topography is interrupted by mountains, craters, and valleys, and these hidden terrains can be precisely known from occultation observations. Therefore, it is a normal idea and phenomenon for small pearl-like beads to be caused by mountains and valleys during the progress of the eclipse. On the center line of the eclipse, Baily’s beads are visible for only a few seconds, while at the edges of the path of totality, the time Baily’s beads can be seen is somewhat longer.
When only one small bead is left, it looks like a diamond set next to the lunar silhouette, surrounded by a ring of light. In practice, general observers refer to the last flash of brilliant light before totality or the first flash after totality as the diamond ring, usually appearing before Baily’s beads prior to totality, or after Baily’s beads following third contact.
Baily’s beads are a string of luminous bright spots appearing on the edge of the black Moon during “second contact” (just beginning) or “third contact” (just ending) of a total solar eclipse. This is caused by the Moon’s uneven peaks cutting off the solar photosphere’s light, looking like a diamond ring; this phenomenon was originally discovered by British astronomer Francis Baily in 1838 and 1842.
Because Baily’s beads are only visible for a moment (about half a second to over a second) during second or third contact, they make the total solar eclipse very beautiful and precious. Capturing Baily’s beads is also one of the most important tasks for astrophotography enthusiasts during the entire total solar eclipse photography process.
It is unsafe to view Baily’s beads or the diamond ring without proper protection, as the Sun’s photosphere is still visible at this time.
NASA Website: http://antwrp.gsfc.nasa.gov/apod/astropix.html
When reprinting, please include the original address of this article: https://kexue.fm/archives/66
For more detailed reprinting matters, please refer to: Scientific Space FAQ