Image of transit taken by NASA's Solar Dynamics Observatory spacecraft

The 2012 transit of Venus, when the planet Venus appeared as a small, dark disk moving 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, eight years apart, which are themselves separated by more than a century:^[2] The previous transit of Venus took place on 8 June 2004 (preceded by the pair of appearances on 9 December 1874 and 6 December 1882), and the next pair of transits will occur on 10–11 December 2117 and in December 2125.^[3]

Observations of the event [edit]

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]

High-definition images of the event were provided by NASA's 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] (SOHO was not in a good position to view the transit due to the size of its lissajous orbit centered about L₁.)

Research [edit]

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 during the transit of Venus on June 5–6, 2012.^[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.

Gallery [edit]

North America:

• 

  San Francisco, California, USA
  Transit of airliner with Venus

• 

  Anacortes, Washington, USA

• 

  Tempe, Arizona, USA
  01:54 UTC

• 

  Wichita Falls, Texas, USA

• 

  Fennell Observatory
  Oakland, Tennessee, USA

• 

  Toronto, Ontario, Canada
  23:06 UTC

Europe:

• 

  Nowy Dwór Mazowiecki, Poland
  06:18 UTC

• 

  Ragusa, Sicily, Italy
  04:11 UTC

• 

  Moscow, Russia

• 

  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

• 

  Chennai, India
  03:24:56 UTC

• 

  Guangzhou, China
  00:41 UTC

• 

  Photo sequence from Taichung, Taiwan

• 

  Handa, Aichi, Japan
  23:36–04:50 UTC

Australasia:

• 

  Sydney
  23:25 UTC

• 

  Wagga Wagga
  00:49 UTC

• 

  Clayton
  01:06 UTC

Others:

•  

  Solar Dynamics Observatory Ultra-high Definition View

•  

  This visualization shows the orbital paths of Venus and Earth that led to this rare alignment on 5–6 June 2012

• 

  Venus transit, seen here from the International Space Station.

• 

  Close-up of Venus by the Japanese Hinode spacecraft on the sun-synchronous orbit.

•  

  GOES-15 Solar X-ray Imager shows a 2-hour longer transit due to Venus' passing in front of the Corona.^[12]

•  

  Visualization generated by compositing the small field-of-view, high-cadence closeups of Venus with the full-disk, low-cadence imagery from SDO.

References [edit]

Further reading [edit]

External links [edit]

Wikimedia Commons has media related to: 2012 Transit of Venus

• NASA – 2012 Transit of Venus Live Webcast and Celebration!
• AstronomyLive.com – Watch Transit of Venus 2012 LIVE – Many Live Webcasts / Broadcasts
• TRANSIT OF VENUS: Live Webcast (Multipoint) – by SWAN-India
• Transit of Venus.org
• National Solar Observatory – Transit of Venus June 5–6 2012
• Venus Transit 2012 Online Simulator
• Transit of Venus viewing guide
• Transit of Venus: live webcast from Australia, Japan and Norway (GLORIA EU project)
• The Transit of Venus, by Niruj Mohan Ramanujam, National Centre for Radio Astrophysics, Pune, India. Illustrated by Reshma Barve
• Missed the Venus Transit in 2012? Watch It Online Until 2117, By Alessondra Springmann, PCWorld, Jun 6, 2012 11:09 a.m.
• NASA Astronomy Picture of the Day live updated image of the sun from the Solar Dynamics Observatory

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