Transit of Venus across the Sun visible from Earth on 5–6 June 2012
The 2012 transit of Venus, when the planet
Venus appeared as a small, dark spot passing across the face of the
Sun, began at 22:09
UTC on 5 June 2012, and finished at 04:49 UTC on 6 June.[1] Depending on the position of the observer, the exact times varied by up to ±7 minutes.
Transits of Venus are among the rarest of predictable celestial
phenomena and occur in pairs. Consecutive transits per pair are spaced 8 years apart, and consecutive pairs occur more than a century apart:[2] The
previous transit of Venus took place on 8 June 2004 (preceded by transits on 9 December 1874 and 6 December 1882); the next pair of transits will occur on 10–11 December 2117 and December 2125 within the
22nd century.[3]
Observations of the event
The entire transit was visible from the western
Pacific Ocean, northwesternmost North America, northeastern Asia, Japan, the
Philippines, eastern Australia, New Zealand, and high
Arctic locations including northernmost
Scandinavia, and
Greenland.[4] In North America, the
Caribbean, and northwestern South America, the beginning of the transit was visible on 5 June until sunset. From sunrise on 6 June, the end of the transit was visible from
South Asia, the
Middle East,
east Africa, and most of
Europe. The phenomenon was not visible from most of
South America, nor from
western Africa. There were a number of live online video streams with footage from telescopes around the world. Midway through the transit one of the NASA streams had nearly 2 million total views and was getting roughly 90,000 viewers at any given moment.
In
Los Angeles, crowds jammed Mount Hollywood where the
Griffith Observatory set up telescopes for the public to view the transit. In Hawaii, hundreds of tourists watched the event on
Waikiki Beach where the
University of Hawaii set up eight telescopes and two large screens showing webcasts of the transit.[5] The transit was also observed and historically photographed by NASA astronaut
Don Pettit aboard the
International Space Station.[6]
NASA's
Solar and Heliospheric Observatory could not see the transit as it was not in between the Earth and the Sun at the time of the event, but high-definition images of the event were obtained by
Solar Dynamics Observatory, from 36,000 km (22,000 mi) above the Earth. Agency astrophysicist Dr. Lika Guhathakurta said, "We get to see Venus in exquisite detail because of SDO's spatial resolution, SDO is a very special observatory. It takes images that are about 10 times better than a high-definition TV and those images are acquired at a
temporal cadence of one every 10 seconds. This is something we've never had before".[7]
Research
The 2012 transit gave scientists a number of research opportunities. These included:[8][9][10]
Measurement of dips in a star's brightness caused by a known planet transiting a known star (the Sun). This will help astronomers when searching for
exoplanets. Unlike the 2004 Venus transit, the 2012 transit occurred during an active phase of the 11-year activity cycle of the Sun, and would have provided practice in detecting a planet's signal around a "spotty"
variable star.
Measurement of the apparent diameter of Venus during the transit, and comparison with its known diameter. This will have given information on how to estimate exoplanet sizes.
The number of locations documenting the event will provide much data via
parallax that will generate more accurate measurements.
Observation of the atmosphere of Venus simultaneously from Earth-based telescopes and from the
Venus Express spacecraft. This gave a better opportunity to understand the intermediate level of Venus's atmosphere than is possible from either viewpoint alone, and should provide new information about the
climate of the planet.
Spectrographic study of the atmosphere of Venus. The results of analysis of the well-understood atmosphere of Venus will be compared with studies of exoplanets with atmospheres that are unknown.
The
Hubble Space Telescope used the
Moon as a mirror to study the light reflected from Venus to determine the makeup of its atmosphere. This may provide another technique to study exoplanets.
Experimental reconstruction of
Lomonosov's discovery of Venusian atmosphere (1761) with antique refractors.[11] The researchers observed the "Lomonosov's arc" and other aureole effects due to Venus's atmosphere and concluded that Lomonosov's telescope was fully adequate to the task of detecting the arc of light around Venus off the Sun's disc during ingress or egress if proper experimental techniques as described by Lomonosov in his 1761 paper are employed.[11]
Gallery
North America:
San Francisco, California, United States Transit of airliner with Venus
^
abKoukarine, Alexandre; Nesterenko, Igor; Petrunin, Yuri; Shiltsev, Vladimir (November 2013). "Experimental Reconstruction of Lomonosov's Discovery of Venus's Atmosphere with Antique Refractors During the 2012 Transit of Venus". Solar System Research. 47 (6). Springer: 487–490.
arXiv:1208.5286.
Bibcode:
2013SoSyR..47..487K.
doi:
10.1134/S0038094613060038.
Further reading
Anderson, Mark (2012). The Day the World Discovered the Sun: An Extraordinary Story of Scientific Adventure and the Race to Track the Transit of Venus. Boston:
Da Capo Press.
ISBN978-0-306-82038-0.