2012 transit of Venus

Visibility map

Animation of simulated transit in equatorial coordinates and CEST

Main article: Transit of Venus

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. 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: the previous transit was in June 2004, and the next pair of transits will not occur until December 2117 and December 2125.

Visibility

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. 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. It was not visible from most of South America or western Africa.

Transit start and end times (in UTC) are available for various non-US cities and various US cities.

Research

The 2012 transit will give scientists a number of research opportunities. These include:

• 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 occurs during an active phase of the 11-year activity cycle of the Sun, and is likely to provide 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 give information on how to estimate exoplanet sizes.
• Observation of the atmosphere of Venus simultaneously from Earth-based telescopes and from the Venus Express spacecraft. This will give a better opportunity to understand the intermediate level of Venus's atmosphere than is possible from either viewpoint alone, and will 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 will use 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.

Observing

The safest way to watch a transit is to observe an image of the Sun projected onto a screen through a telescope, binoculars, pinhole or reflected pinhole. The event can be viewed without magnification using filters specifically designed for this purpose, such as an astronomical solar filter or eclipse viewing glasses coated with a vacuum-deposited layer of chromium. However, the disk of Venus is tiny compared to the sun and not much will be seen. The once-recommended method of using exposed black-and-white film as a filter is not considered safe now, as small imperfections or gaps in the film may permit harmful UV rays to pass through. Observing the Sun directly without appropriate protection can damage or destroy retinal cells, causing temporary or permanent blindness.

NASA aired a live webcast of the transit from Mauna Kea, Hawaii.

Contacts

There are four named "contacts" during a transit—moments when the circumference of Venus touches the circumference of the Sun at a single point:

1. First contact (external ingress): Venus is entirely outside the disk of the Sun, moving inward
2. Second contact (internal ingress): Venus is entirely inside the disk of the Sun, moving further inward
3. Third contact (internal egress): Venus is entirely inside the disk of the Sun, moving outward
4. Fourth contact (external egress): Venus is entirely outside the disk of the Sun, moving outward.

A fifth named point is that of greatest transit, when Venus is at the middle of its path across the solar disk and which marks the halfway point in the timing of the transit.

Gallery

Asia/Middle East:

• 
  Almaty, Kazakhstan
• 
  Kuwait City, Kuwait
• 
  Seoul, South Korea
  23:57 UTC
• 
  Guangzhou, China
  00:41 UTC

Australia:

• 
  Sydney, Australia
  23:25 UTC

Europe:

• 
  Assisi, Italy
  06:10 CEST

India:

• 
  Pune, India
  09:03 IST

North America:

• 
  Anacortes, Washington, USA
• 
  Medford, Oregon, USA
• 
  Salt Lake City, Utah, USA
• 
  Tempe, Arizona, USA
  01:54 UTC
• 
  Minneapolis, Minnesota, USA
  23:01 UTC
• 
  St. Paul, Minnesota, USA
• 
  Arrowhead Park Naperville, Illinois, USA
  1:10 UTC
• 
  Toronto, Ontario, Canada
  19:06 EDT
• 
  Syracuse, New York, USA

Others:

• From Mauna Loa, Hawaii, USA[15]
  From Mauna Loa, Hawaii, USA
• Venus 2012 transit animation
• This visualization shows the orbital paths of Venus and Earth that led to this rare alignment on June 5, 2012.

Further reading

• Sheehan, William (2004). The Transits of Venus. Amherst, New York: Prometheus Books. ISBN 1-59102-175-8. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Lomb, Nick (2011). Transit of Venus: 1631 to the Present. Sydney, Australia: NewSouth Publishing. ISBN 978-1-74223-269-0. OCLC 717231977.
• Wulf, Andrea (2012). Chasing Venus: The Race to Measure the Heavens. New York: Knopf. ISBN 978-0307700179.
• 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 978-0306820380.
• Sellers, David (2001). The Transit of Venus: the Quest to Find the True distance of the Sun. Leeds: Magavelda Press. ISBN 0-954-1013-0-8.

External links

• NASA – 2012 Transit of Venus Live Webcast and Celebration!
• NASA Astronomy Picture of the Day live updated image of the sun from the Solar Dynamics Observatory
• 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