Scientists gather in Detroit to watch Venus transit
Crowd gathers at Wayne State University to witness Venus cross between Sun, Earth
A crowd gathered on the roof of the Wayne State University physics building to observe a rare celestial event: The transit of Venus.
The planet began crossing in front of the Sun at about 6:04 p.m.
"We'll see it as a black dot one thirtieth the size of the sun," said Jeff Conn, senior lecturer for the Department of Physics and Astronomy.
In the 1700s, astronomers used the transit to calculate for the first time that the Sun is 93 million miles from the Earth.
Today, scientists will measure how much sunlight is blocked by Venus. It's a kind of benchmark for detecting distant planets.
"Dips in the light curves are seen as an exo-planet as passes in front of that star," said Conn.
More: How to watch the Venus transit
The public is invited to view the phenomenon until sunset. Clouds were threatening, but the sun broke through as the planetary speck began passing across the sun. It will take about six hours, though Michiganders will have little more than half that time before sunset.
"The next one isn't happening until 2117," said Conn. "That's 105 years from now."
NASA images of the transit will be displayed in the physics building, along with science experiments and a planetarium show nearby. Visitors can view for free.
The Wayne State telescopes have solar filters. Seeing the transit without specialized equipment is likely to damage the retinas of onlookers.