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Why is it Dark at Night? A Modern Look at Olber’s Paradox

by Brea Aamoth on February 14th, 2017

A Presentation by Dr. Tom Geballe of Gemini Observatory

Date: Fri. March 3
Time: 7:00p.m. – 8:00p.m.
Cost: $10 ($8 for members)

The sky is dark at night —this is a fundamental observational fact of cosmology that can be observed by everyone. This is also fundamental to our existence, to our physiology and to our cultures. The obvious answer to the question “why is it dark at night?” is that the sun is shining on the other side of the Earth, and the light of the distant stars is much weaker than the sun. But how is this possible when there are so many stars that have been shining for so long? And how dark is the sky? Is it dark only to eyes like ours that are sensitive to visible light, or is it also dark to infrared, ultraviolet, x-ray and radio ‘eyes’?

Join us at ‘Imiloa on Friday, March 3 at 7:00 p.m. as Dr. Tom Geballe of Gemini Observatory answers these questions, as well as delving into historical and scientific attempts to understand this simple yet important observation. Dr. Geballe will discuss Olber’s Paradox: a historical argument that states the darkness of the night sky conflicts with the assumption of an infinite and eternal “static universe”. Olber’s Paradox argues that if the universe is populated by an infinite amount of stars, and if the universe has existed for an infinite amount of time, then any sight line from Earth must end at the very bright surface of a star. This paradox states that the night sky should be bright in a static universe, contradicting the observed darkness of night.

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Dr. Geballe received his Bachelor’s degree in Physics from the University of California at Berkeley and his PhD in Physics from Berkeley. After one postdoctoral year at Berkeley, two years as a Research Fellow at Leiden University in the Netherlands, and four years as a Carnegie Fellow in Pasadena, he moved to Hawaii to join the staff of the United Kingdom Infrared Telescope (UKIRT). In 1987 he became UKIRT’s Astronomer-in-charge, in 1990 its Associate Director, and in 1994 its Head of Operations. In 1998 he accepted a tenured astronomer position at Gemini Observatory, where he is currently employed.

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General admission tickets are $10, $8 for members (member level discounts apply). Pre-purchase tickets at ‘Imiloa’s front desk or by phone at 808-932-8901.

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