Director of the University of North Texas Astronomy Laboratory Program and planetarium.

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DENTON (UNT), Texas -- 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 of citizen-scientists from the University of North Texas will attempt to complete the experiment on June 5 (Tuesday) during this century's last Venus transit.

"Scientists have been able to calculate the astronomical unit, but we want to validate that the methods proposed by Edmund Halley in the 18th century were sound," says Ron DiIulio, director of UNT's astronomy program and leader of the expedition.

DiIulio will lead a team to Anchorage, Alaska, and Preston Starr, UNT observatory manager, will lead a team to South Point, Hawaii. These locations will allow the teams to capture the entire Venus transit before the sun sets.

In addition to the teams in Alaska and Hawaii, Randy Peters, UNT planetarium manager, will lead a viewing of the transit on the UNT campus. The viewing is open to the public and will be held in the parking lot on the western side of UNT's Environmental Education, Science and Technology Building. Venus will make first contact with the sun in North Texas at 5:07 p.m. on June 5 (Tuesday), and second contact at 5:22 p.m.

Team representatives will travel to Albuquerque, N.M., to film the upcoming solar eclipse on May 20 (Sunday) as a practice run for the Venus expedition. The teams will get only one chance to capture the transit of Venus across the sun, since the event occurs twice over an eight year span, and then doesn't occur again for more than 100 years. Venus last transited the sun in 2004.

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.