Baily's beads

Baily's beads

As the moon "grazes" by the Sun during a solar eclipse, the rugged lunar topography allows beads of sunlight to shine through in some places, and not in others. This effect is called "Baily's beads", in honour of Francis Baily, who first provided an exact explanation of the phenomenon in 1836. [cite book |last=Littmann |first=Mark |authorlink=Mark Littmann |coauthors=Willcox, Ken; Espenak, Fred |title=Totality - Eclipses of the Sun |year= 1999 |publisher=Oxford University press |language=english |isbn=0195131797 |pages=65-66]

Lunar topography has considerable relief because of the presence of mountains, craters, valleys, etc. The irregularities of the lunar limb profile (the "edge" of the Moon, as seen from a distance) are known accurately from observations of grazing occultations of stars. Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear in advance of the eclipse. While Baily's beads are seen briefly for a few seconds at the center of the eclipse path, their duration is maximized near the edges of the path of the umbra, reaching 1–2 minutes.

The Baily's beads phenomenom is seen during the credit opening sequence of the NBC TV show Heroes.

External links

* [http://umbra.nascom.nasa.gov/eclipse/980226/rp.html Reference Publication on the Total Solar Eclipse of 1998 February 26.]
* [http://www.exploratorium.edu/eclipse/what2.html What to See During an Eclipse Continued.]

References


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Look at other dictionaries:

  • Baily's beads — Bai ly s beads (Astron.) A row of bright spots observed in connection with total eclipses of the sun. Just before and after a total eclipse, the slender, unobscured crescent of the sun s disk appears momentarily like a row of bright spots… …   The Collaborative International Dictionary of English

  • Baily's beads — [bā′lēz] n. [after F. Baily (1774 1844), Eng astronomer] bright spots visible along the rim of the moon during a total eclipse of the sun, just before or after totality, caused by sunlight passing through the moon s valleys and clefts …   English World dictionary

  • baily's beads — ˈbālēz , liz noun plural Usage: usually capitalized 1st B Etymology: after Francis Baily died 1844 English astronomer who described them : the row of brilliant points of sunlight shining through valleys on the edge of the moon that are seen for a …   Useful english dictionary

  • Baily's beads — /bay leez/ spots of light that appear to encircle the moon, resembling a string of luminous beads, visible immediately before and after a total eclipse, caused by the sun s light shining between the mountains on the moon s surface. Cf. diamond… …   Universalium

  • Baily's beads — Bai′ly s beads′ [[t]ˈbeɪ liz[/t]] n. pl. astron. spots of sunlight encircling the moon immediately before and after a total solar eclipse • Etymology: 1865–70; after Francis Baily (1774–1844), English astronomer …   From formal English to slang

  • Baily's beads — plural noun Astronomy a string of bright points seen at the edge of the darkened moon at the beginning or end of totality in an eclipse of the sun, caused by the uneven lunar topography. Origin C19: named after the English astronomer Francis… …   English new terms dictionary

  • Baily, Francis — ▪ British astronomer born April 28, 1774, Newbury, Berkshire, Eng. died Aug. 30, 1844, London  astronomer who detected the phenomenon called “Baily s beads” during an annular eclipse of the Sun on May 15, 1836. His vivid description aroused new… …   Universalium

  • Francis Baily — Infobox Scientist name = Francis Baily box width = image width = 150px caption = Royal Astronomical Society photo birth date = 28 April 1774 birth place = Newbury in Berkshire death date = 30 August 1844 death place = London residence =… …   Wikipedia

  • Bailey's beads — Bailey s beads, = Baily s beads. (Cf. ↑Baily s beads) …   Useful english dictionary

  • Francis Baily — (* 28. April 1774 in Newbury, Berkshire; † 30. August 1844 in London) war ein englischer Astronom. Er beschäftigte sich insbesondere mit Sternk …   Deutsch Wikipedia

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