How to Observe the Transit of Venus

In 2012, an infrequently viewable sight will grace our skies in the form of the transit of Venus. This means that Venus will pass across the face of the Sun and we will be able to see Venus in silhouette. Since this won't happen again until 2117, catching it in 2012 is probably a good idea!


  1. Image titled Observe the Transit of Venus Step 1
    Put the date down in your calendar. It will occur on 5-6 June 2012. Naturally, also hope for cloudless skies and good weather wherever you are! Also, do some research about the transit of Venus.
  2. Image titled Observe the Transit of Venus Step 2
    Be in the right location. The best viewpoint will be from the Pacific Ocean.[1] The entire transit (all four contacts, see below) is visible from northwestern North America, Hawaii, the western Pacific, northern Asia, Japan, Korea, eastern China, Philippines, eastern Australia, and New Zealand. The Sun sets while the transit is still in progress from most of North America, the Caribbean, and northwest South America. Similarly, the transit is already in progress at sunrise for observers in central Asia, the Middle East, Europe, and eastern Africa. No portion of the transit will be visible from Portugal or southern Spain, western Africa, and the southeastern two thirds of South America.
  3. Image titled Observe the Transit of Venus Step 3
    Understand that the principal events occurring during the transit are characterized by contacts.
    • The event begins with contact I which is the instant when the planet's disk is externally tangent with the Sun.
    • The entire disk of the Venus is first seen at contact II when the planet is internally tangent with the Sun. During the next several hours, Venus gradually traverses the solar disk at a relative angular rate of approximately 4 arc-minutes per hour.
    • At contact III, the planet reaches the opposite limb and is once again internally tangent with the Sun.
    • The transit ends at contact IV when the planet's limb is externally tangent to the Sun.
    • Contacts I and II define the phase called ingress while contacts III and IV are known as egress. Greatest transit is the instant of minimum angular separation between Venus and the Sun as seen from Earth's geocenter.
  4. Image titled Observe the Transit of Venus Step 4
    Take appropriate eye safety precautions to protect your eyes when viewing the transit. Do not look directly at the sun with the naked eye or unprotected binoculars or telescopes; you risk permanently blinding yourself. However, do not be dissuaded by this; proper viewing techniques can permit you to view safely:
    • Read the NASA guidelines on safe observation of eclipses. These can be found at:
    • The safest observation method involves projecting the Sun's image through a telescope, binoculars, or pinhole onto a screen.[2]
    • Use a filter approved for safe solar viewing.[3] Approved filters can allow viewing with the naked eye, such as an astronomical solar filter that has a vacuum-deposited layer of chromium, or eclipse viewing glasses like Eclipse Shades or Solar Shades, or Grade 14 (or darker) welder's glass. If wishing to see the transit magnified, you'll need to get an appropriate solar filter for your telescope. The lens must fit properly and not be makeshift. You can also purchase solar binoculars or special telescopes that have in-built hydrogen-alpha filters if preferred.
  5. Image titled Observe the Transit of Venus Step 5
    Know what to expect. Using your approved filter or other safe method of viewing, you will be able to see a small black dot that is about 1/30th the size of the solar disk. It will move across the Sun very slowly.[4]
  6. Image titled Observe the Transit of Venus Step 6
    Enjoy the sight. Given it has a 120 year cycle, there will be many people who will never have this opportunity, so grasp it while it's there. Some other things you can do include:
    • Write a poem, story, or letter about it to be passed down to your grandchildren some day.
    • Hold a street party to celebrate the event.
    • Watch webcasts.
    • Have a ball!


  • Transits of Venus across the disk of the Sun are among the rarest of planetary alignments. Indeed, only six such events have occurred since the invention of the telescope (1631, 1639, 1761, 1769, 1874 and 1882). They always come in pairs, 8 years apart, every 120 years.[5]
  • Whether the transit occurs on the 5th or 6th of June is dependent on your location.
  • Earth, Venus, and the Sun will line up in a row when the nodes of the planetary orbits intersect on 5-6 June 2012, but there won't be any cataclysmic events. Anyone who insists that bad things will happen as a result of this is scamming and is someone who can join the long line of Doomsday prophets who have foretold many non-events.


  • Do not look direct at the sun with the naked eye or direct through a telescope or binoculars. To do so can cause temporary or permanent loss of vision through destruction of retinal cells.[6]
  • Do not use a camera to observe the transit; your retina may burn.[7]
  • Do not use sunglasses to observe the sun. They are not adequate to protect your eyes from direct viewing damage.

Things You'll Need

  • Appropriate viewing mechanism as outlined above
  • Clear viewing place and right location
  • Internet research ability

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