Shadow bands
Encyclopedia
Shadow bands are thin wavy lines of alternating light and dark that can be seen moving and undulating in parallel on plain-coloured surfaces immediately before and after a total solar eclipse. They are caused by the thin slot-like solar crescent illuminating the Earth's atmosphere moments before and after the eclipse totality
, Their movement is caused by atmospheric winds.
In 2008, Dr. Stuart Eves suggested that shadow bands might be caused by infrasound
, which involves the shadow of the moon travelling at supersonic speed, which in turn produces low frequency sound that humans can't hear. Due to this, he theorized, the movement of the moon creates a shock-wave in front of the shadow, which causes shadow bands. Dr. Eves said "If proven, it would be a something of a revelation that eclipses are a sonic as well as an optical phenomenon." Professor Brian Jones stated "The [accepted] theory works, there's no need to seek an alternative".
Shadow bands have been noted throughout history:
Totality
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, Their movement is caused by atmospheric winds.
In 2008, Dr. Stuart Eves suggested that shadow bands might be caused by infrasound
Infrasound
Infrasound is sound that is lower in frequency than 20 Hz or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high...
, which involves the shadow of the moon travelling at supersonic speed, which in turn produces low frequency sound that humans can't hear. Due to this, he theorized, the movement of the moon creates a shock-wave in front of the shadow, which causes shadow bands. Dr. Eves said "If proven, it would be a something of a revelation that eclipses are a sonic as well as an optical phenomenon." Professor Brian Jones stated "The [accepted] theory works, there's no need to seek an alternative".
Shadow bands have been noted throughout history:
- In the 9th century AD shadow bands during a total eclipseTotal EclipseA total eclipse is an eclipse where either the Sun is entirely covered by the Moon, or the Earth's shadow entirely covers the Moon.Total Eclipse may also refer to:-Music:* Total Eclipse , a Goa trance music group...
are described for the first time-in the Völuspá, part of the old Icelandic poetic eddaPoetic EddaThe Poetic Edda is a collection of Old Norse poems primarily preserved in the Icelandic mediaeval manuscript Codex Regius. Along with Snorri Sturluson's Prose Edda, the Poetic Edda is the most important extant source on Norse mythology and Germanic heroic legends, and from the early 19th century...
.
- In 1820, Carl Wolfgang Benjamin Goldschmidt of Germany calls attention to the shadow bands visible just before and after totality at some eclipses.
- In 1842, George B. Airy, the English astronomer royal, saw his first total eclipse of the sun. He recalled shadow bands as one of the highlights: "As the totality approached, a strange fluctuation of light was seen upon the walls and the ground, so striking that in some places children ran after it and tried to catch it with their hands"
External links
- Shadow bands during a total solar eclipse, by Dr. Wolfgang Strickling