UC Berkeley researchers and astronomy enthusiasts throughout the Bay Area are gearing up for a once-in-a-century celestial event Tuesday known as the transit of Venus.
In this rare astronomical event, the planet Venus will begin to cross between the Earth and the sun at 3:07 p.m. and become visible at 3:24 p.m. as a tiny black dot moving across the sun’s yellow surface, according to UC Berkeley Astronomy Professor Alex Filippenko in a document sent to students and colleagues informing them of the transit.
Although the transit will end at 9:47 p.m., Bay Area viewers will miss the end of the transit since sunset will occur around 8:28 p.m.
In order to view the full transit — which will occur across the International Date Line — many dedicated astronomers are traveling to the state of Hawaii, Filippenko mentioned in the document.
Transits of Venus usually come in pairs. Tuesday’s transit will be the partner of the transit that took place in 2004, which was not visible from the Western Hemisphere. It will be another 105 years before the next pair in 2117 and then in 2125 pass across the sun.
According to Filippenko, transits of Venus in 1761 and 1769 played an important historical role in helping scientists attain the first accurate estimate of the Earth’s distance from Venus and, subsequently, Earth’s distance from the sun.
“Today the celestial event is an important demonstration of the technique used by scientists to discover exoplanets — planets circling other stars outside of our Solar System,” Filippenko said in the document.
When Venus passes across the sun, the total brightness of the sun periodically drops a tiny bit. Scientists are also able to detect this drop in brightness from stars outside of the solar system when exoplanets transit across their surface.
“The Kepler mission is looking for this very phenomenon around other stars,” said Aaron Lee, a graduate student in astrophysics, in an email. “Astronomers use transits of Solar System planets to better develop observing programs to find transiting extrasolar planets.”
The Lawrence Hall of Science is hosting a planetarium program on transits of Venus until Sunday. On Tuesday, the hall will also set up several solar telescopes on their main plaza starting at 2:30 p.m. for the general public to view the transit safely.
UC Berkeley astronomy professor Geoff Marcy said in an email that he also plans to view the transit by setting up a desk on Sproul Plaza from 3:30 p.m. to 6 p.m.
The transit will be barely visible to the unaided human eye. Because it is dangerous to look at the sun with the naked eye, Filippenko recommends using a piece of Shade 14 Welder’s glass or a safe solar filter that will block the sun’s rays at visible, ultraviolet and infrared wavelengths. Using a telescope or binoculars with a proper solar filter attached will give a better magnified view of the transit.
“Witnessing this transit combines so much about what makes the Universe truly awesome,” said Lee. “You are seeing a planet that is not much smaller than the Earth, and you are seeing it in earnest.”
The transit of Venus is the third in a series of astronomical events viewable from the area that have taken place in less than a month’s time. A partial eclipse of the full moon on Monday will occur in the early morning around 3 a.m. just prior to moonset. An annular solar eclipse also took place on May 20.