The sky is dark at night — this is a fundamental observational fact of cosmology that can be observed by everyone. This also is fundamental to our existence, physiology and cultures.
The sky is dark at night — this is a fundamental observational fact of cosmology that can be observed by everyone. This also is fundamental to our existence, physiology and 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 astronomer Tom Geballe of the Gemini Observatory as he answers these questions during a talk at 7 p.m. March 3 at the Imiloa Astronomy Center.
In addition to delving into historical and scientific attempts to understand this simple yet important observation, 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 sightline 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.
Geballe received his bachelor’s degree and Ph.D. in physics from the University of California at 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, Calif., he moved to Hawaii to join the staff of the United Kingdom Infrared Telescope. In 1998, he accepted a tenured astronomer position at Gemini Observatory, where he continues his research.
General admission tickets for the March 3 talk are $10, $8 for members (member-level discounts apply). Pre-purchase tickets at Imiloa’s front desk or by phone at 932-8901.
The Imiloa Astronomy Center is located at 600 Imiloa Place on the campus of the University of Hawaii at Hilo. For more information, visit www.imiloahawaii.org.