2012 transit of Venus

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]

Image of the transit taken by NASA's Solar Dynamics Observatory spacecraft. Venus is in the upper right quadrant

Observations of the event
Path across the Sun, with contact times and other data
Visibility map

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 photographed by a flight engineer aboard the International Space Station, Don Pettit.[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
Children in Dili observing the transit of Venus

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]

North America:

  • San Francisco, California, USA
    Transit of airliner with Venus
  • Tempe, Arizona, USA
    01:54 UTC
  • Wichita Falls, Texas, USA
  • Fennell Observatory
    Oakland, Tennessee, USA
  • Toronto, Ontario, Canada
    23:06 UTC

Europe:

  • Ragusa, Sicily, Italy
    04:11 UTC
  • Moscow, Russia
    03:47 UTC
  • Helsingborg, Sweden
    04:20 UTC
  • Úvaly, Czech Republic
    04:26 UTC
  • Kecskemét, Hungary
    03:41 UTC

Asia:

  • Kuwait City, Kuwait
  • Amman, Jordan
    Combination of 3 exposures
  • Delhi, India
  • Guangzhou, China
    00:41 UTC
  • Photo sequence from Taichung, Taiwan
  • Ussuriysk, Russia
    00:08–04:43 UTC
  • Handa, Aichi, Japan
    23:36–04:50 UTC

Australasia:

  • Sydney
    23:25 UTC
  • Wagga Wagga
    00:49 UTC
  • Clayton
    01:06 UTC

Others:

gollark: If you just define anything which happens as being part of the balance retroactively, then it is not meaningful to complain about it.
gollark: Well, it's a thing which happens in nature.
gollark: There was an experiment which wanted to demonstrate group selection. They put flies that in an environment with limited resources which could only support so many fly children. If nature was nice and kind, they would magically turn down their breeding. As is quite obvious in retrospect, evolutionary processes would *never do this* and they cannibalized each other's young.
gollark: There are nasty things like those various parasitic wasps.
gollark: Yes, something something just world fallacy.

References
  1. Espenak, Fred. "2012 Transit of Venus". NASA. Retrieved 6 June 2012.
  2. Withrow, Jay (2 June 2012). "Venus-sun event rarer than Halley's Comet". Omaha World-Herald. Archived from the original on 7 September 2012. Retrieved 6 June 2012.
  3. Klotz, Irene (6 June 2012). "Venus transit offers opportunity to study planet's atmosphere (+video)". Christian Science Monitor. Retrieved 6 June 2012.
  4. Grego, Peter; Wulf, Andrea; Cooper, Keith (June 2012). "The Transit of Venus". Astronomy Now. Pole Star Publications: 58–61. ISSN 0951-9726.
  5. "Last transit of Venus this century draws stargazers around the world". The Guardian. 6 June 2012. Retrieved 6 June 2012.
  6. "Stargazers watch rare Venus transit". Al Jazeera. 6 June 2012. Retrieved 6 June 2012.
  7. Amos, Jonathan (6 June 2012). "Venus makes rare trek across Sun". BBC News. Retrieved 6 June 2012.
  8. Wall, Mike (16 May 2012). "Venus Transit On June 5 May Bring New Alien Planet Discoveries". The Huffington Post. Retrieved 6 June 2012.
  9. "Counting down to the Transit of Venus – our nearest exoplanet test-lab". Phys.Org. 5 March 2012. Retrieved 6 June 2012.
  10. "The Venus Twilight Experiment: Refraction and scattering phenomena during the transit of Venus on June 5–6, 2012". venustex.oca.eu. Archived from the original on 23 October 2016. Retrieved 6 June 2012.
  11. Koukarine, 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. Springer. 47 (6): 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. ISBN 978-0-306-82038-0.
  • Lomb, Nick (2011). Transit of Venus: 1631 to the Present. Sydney, Australia: NewSouth Publishing. ISBN 978-1-74223-269-0. OCLC 717231977.
  • Sellers, David (2001). The Transit of Venus: the Quest to Find the True distance of the Sun. Leeds: Magavelda Press. ISBN 0-9541013-0-8.
  • Sheehan, William; Westfall, John (2004). The Transits of Venus. Amherst, New York: Prometheus Books. ISBN 1-59102-175-8.
  • Wulf, Andrea (2012). Chasing Venus: The Race to Measure the Heavens. New York: Knopf. ISBN 978-0-307-70017-9.


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