University of North Texas

By Alyssa Yancey, News Promotions

In 1769, British Capt. James Cook led an expedition to Tahiti to document the transit of Venus across the sun in an effort to calculate the astronomical unit – the earth’s distance from the sun.

Cook was unable to complete the experiment due to unfavorable weather conditions, and later, a run-in with natives. Now, nearly 250 years later, a team from the astronomy program will attempt to complete the experiment June 5. The next pair of transits will be in more than a century, 2117 and 2125.

Ron DiIulio, right, director of the astronomy program and team leader, will travel to Alaska, and Preston Starr, observatory manager, to Hawaii. These locations will allow the teams to capture the entire Venus transit before the sun sets.

You can watch the transit right here on campus June 5.

Randy Peters, planetarium manager, will lead a viewing of the transit in the parking lot on the west side of the Environmental Education, Science and Technology Building. Venus will make first contact with the sun in North Texas at 5:07 p.m. and second contact at 5:22 p.m. Sunset is at 8:35 p.m.

• Find a NASA video of the last Venus transit in 2004.
• Enter to win a UNT-branded water bottle - perfect for stayng hydrated during summer stargazing expeditions - by sending an email to InHouse with "Venus" in the subject line by 5 p.m. June 5. Winners will be selected at random from all responses.

“Scientists have been able to calculate the astronomical unit, but we want to validate that the methods proposed by Edmund Halley - of comet fame - in the 18th century were sound,” says DiIulio.

Team representatives traveled to Albuquerque to film the May 20 solar eclipse as practice for the Venus expedition. 

DiIulio’s team will have the advantage of atomic clocks, GPS positioning and high-tech telescopes, whereas, Cook’s expedition had to spend eight months bringing grandfather clocks across the ocean. Canon also will provide the teams with film equipment specifically designed for astronomy, which will allow them to capture high-quality, time-lapse footage of the event.

The team hopes to produce a planetarium show using the footage from the expedition. They also are planning a documentary about amateur scientists.

“The transit of Venus across the sun has only happened six times since the invention of the telescope, so this expedition will allow us to see how far we have come. It truly speaks to the spirit of adventure,” says DiIulio.

Below, Venus transiting the sun in 2004. (Photo courtesy of NASA/Lockheed Martin Solar and Astrophysics Laboratory)