The Baily's beads are visible not on a lunar eclipse, but during an eclipse of the Sun by the Moon. During an annular eclipse of the sun can observe this phenomenon called Baily's beads. This is due to the topography of the surface of the moon (presence of mountains, craters, valleys,...). It has been described vividly by Francis Baily who noted this phenomenon in 1836. These abrasions of the Moon sunlight during a solar eclipse, allows beads of sunlight to shine through places and disappear in others. As we know perfectly irregularities lunar profile, astronomers can calculate in advance the appearance of beads on the circle of the eclipse. Baily's beads appear briefly for a few seconds on the path of light around the edges and their duration is 1 to 2 minutes. A Flash Red appears just after the vision of Baily's beads. This short passage has the effect to bright pink color, the solar corona. The red color is due to the hydrogen alpha line radiating at this wavelength.
The diamond ring or diamond Airy is the last portion of the sun silhouetted behind the black disk of the moon. At this point, this image looks like a ring with a diamond shining its thousand lights. It takes place just before or after the eclipse.
Image: Total eclipse of the Sun by the Moon, you can see the Baily beads, flash red, diamond ring or diamond Airy, the chromosphere of the Sun embellished by its coronal jets.
Total eclipse of June 21, 2001
The shadow of the eclipse of June 21, 2001 crossed the African continent, Angola, Zambia, Zimbabwe, Mozambique and Madagascar. The first total solar eclipse of the 21st century took place on 21 June 2001. Zimbabwe has benefited from better weather conditions with an eclipse of 4 min and the Sun at 30 ° above the horizon. For Madagascar which is at the end of the trajectory of the lunar shadow, the duration of the total eclipse at this point is only 2 min 36 s with a 11 ° Sun just above the horizon .
Video: Amateur video of the total solar eclipse of 21 June 2001 that lasted more than 4 minutes. It was taken in Zimbabwe (Africa).
Total eclipse over the Pacific
The total eclipse of the sun obscured by the moon is always a spectacular event, a rare phenomenon which lasts a little more than six minutes. The longest of the century, that of 22 July 2009 lasted 6 min 39 s. When the landscape into the darkness, the temperature drops suddenly becomes silent nature, insects and birds fall silent and men marvel shouting a big WOW!. The same effects occurred during the new moon of November 15, 2012 which completely hid the sun. The bulk of this total solar eclipse took place over the South Pacific, but the shadow of the moon was sighted in northern Australia on November 14 in the morning. The last rays of the sun that successfully pass through the rugged terrain of the Moon produce a beautiful red flash and a diamond ring. As soon as the last rays of the sun disappears behind the lunar mountains, forms a piece called "diamond Airy." When the sun is completely hidden, so you can see its delicate ring around the lunar circle. You can see on this picture, a solar ejection (red) on the limb of the Sun on the upper of the image.
At the top of the blade, sunlight finding ways to sneak through the lunar relief offers magnificent Baily's beads.
Image: Above against the black disk halo of golden eclipse taken 15 November 1992 over Queensland, Australia, northern New South Wales. Image Credit & Copyright: Phil Hart
nota: Sir George Biddell Airy (1801-1892) mathematician, astronomer, surveyor and physicist. He became Astronomer Royal in 1835, author of several theories (theory of rainbows, theory of isostasy), became a member of the Royal Society January 21, 1836.