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A matt black Moon would still raise tides but would pass almost invisibly across the sky. Apart from the variation between the height of spring and neap tides, it would be impossible to tell the phase of the Moon.<\/p>\n
This\u00a0circalunar rhythm is a very important timing signal that many creatures use to synchronise their behaviour. Corals<\/a> on the Great Barrier Reef, for example, use the full Moon<\/a> as the trigger for their annual mass spawning. This ensures that all the polyps have their eggs and sperm in the water at once, which increases the chance of successful fertilisation.<\/p>\n Birds<\/a> also use the lunar cycle to synchronise migrations. For example,\u00a0the seabird Barau\u2019s petrel arrives at its breeding ground on the island of R\u00e9union, in the Indian Ocean, at a different time each year depending on the weather and feeding conditions, but all the birds always arrive together on a full Moon.<\/p>\n What makes the full Moon so useful as a timing cue is that its brightness dramatically increases on the night of the full Moon itself, compared with the nights on either side. This is due to the opposition effect, where shadows on the surface of the Moon (cast by craters and mountains) suddenly disappear when the Moon is lit directly from\u00a0the\u00a0front.<\/p>\n Moonlight is more than just a clock though. Even though it is less than one-thousandth of\u00a01\u00a0per cent as bright as daylight,\u00a0it\u00a0is still\u00a01,000\u00a0times brighter than starlight alone. Without the help of moonlight, nocturnal animals would be restricted to those able to navigate by touch or by echolocation.<\/p>\n The earliest mammals appeared when the daylight hours were dominated by dinosaurs. Mammal vision was, and still is, specially adapted to work well in moonlight. Without the ability to operate at night, mammals might not have evolved at all!<\/p>\n Read more:<\/strong><\/p>\n Asked by: Jakob Kaye, Dumfries and Galloway<\/strong><\/p>\n To submit your questions email us at questions@sciencefocus.com (don\u2019t forget to include your name and location)<\/em><\/p>\n