November 4: Captain Cook and the Cosmic Yardstick

Last Friday, Professor Martin Hendry, from the University of Glasgow, described how the first measurements of the size of the solar system were conducted, first by the ancient Greeks, and later refined by observations of the transit of Venus from two different towns in England. He demonstrated how the geometry of the transit, seen from two different locations, can provide enough information to determine the distance from the Earth to the Sun. Martin then described the voyage of the HMS Endeavor, and how the measurement of the transit of Venus from the island of Tahiti provided the most accurate measurement of the astronomical unit (AU) until Radar allowed for more refined measurements.

Following the talk, Brandon gave a talk on the next few rungs of the distance ladder, and how the measurement of the AU allows us to measure much vaster distances. Jeff, Adrian and Miao enlightened visitors with views of the Moon, Jupiter, and Uranus on the roof, lead by Sam Grunblatt. Jana expertly ran the 3D wall, highlighting some of the more exciting events in the universe, and Jia helped with organizing and ensured that visitors were able to find their way to the roof and movies. Concurrently, Martin Hendry was delivering another talk, this time for an audience of students from one of the astronomy department's other ventures, Rooftop Variables. All in all, it was a very successful night for Columbia Astronomy.

--Brandon