Transit of Venus at GTCC - 5 June 2012


On Tuesday, 5 June, during the hours before sunset, observers in North Carolina had the opportunity to see Venus cross the face of the sun.  Cline Observatory held a special Venus Transit viewing session from 5:30-8:30 p.m. that day in Parking Lot F on the Jamestown Campus.  (Weather played a role - unfortunately, clouds in the area obscured the view after 6:30, but approximately 300 peole attended the session.)


What happens during the transit?

A transit of Venus is sort of like a solar eclipse, except that Venus appears much smaller than the moon, and thus cannot cover the whole sun.  So Venus will appear as a black dot against the bright sun, about 33 times smaller than the apparent diameter of the sun itself.

These events are extremely rare, occurring in pairs separated by over a century.  Only six other transits of Venus have been observed in recorded history (1639, 1761, 1769, 1874, 1882, and 2004).  For images of the 2004 transit taken around the world, see this gallery of transit images at


When will the transit happen?

Around 6:04 p.m. on Tuesday the 5th, Venus will edge onto the face of the sun.  Facing the western horizon as seen from NC, this will happen near the top of the solar disk.  Venus will take about 17½ minutes to work its way completely onto the solar disk, then slowly drift across (downward) the sun until sunset (8:34 p.m. in Jamestown).  Though we will see only about two hours of the transit, the event actually lasts about 6½ hours.  Observers west of NC will see the transit for a longer duration before sunset, and observers in Alaska, the Pacific, and parts of Asia and Australia will see Venus move all the way across the sun.

To find transit timings for a specific location, use the U.S. Naval Observatory Online Transit Computer.

This map shows where on Earth the transit will be visible.


What will happen at GTCC?

Cline Observatory Staff, with assistance from Greensboro Day School faculty and members of the Greensboro Astronomy Club, will set up numerous telescopes equipped with safe solar viewing filters.  Visitors can drop in to get a glimpse of the Sun and Venus together by coming to Parking Lot F any time during the session.  It is not necessary to stay for the duration of the 5:30-8:30 session, but it is worth stopping by to catch a glimpse of the transit and to let local astronomers explain what is happening.  The location of our observing station is shown below.


Can the transit be viewed without coming out to GTCC on the 5th?

You should NOT look directly at the sun without a proper solar filter.  If you do not have such a filter, do not try to improvise one yourself.  See this resource for a list of appropriate techniques and materials.

A limited supply of safe solar viewing glasses is available at GTCC bookstores for $2.  They are also available at Cline Observatory Public Viewings on clear Friday nights before the Transit.  These solar shades are worn like sunglasses and you look directly at the sun.  DO NOT try to use them to look through unfiltered telescopes or binoculars.  These glasses can also be used to view the solar eclipse of 21 August 2017 wisible from the Carolinas.

A time honored method for viewing the sun during eclipses or transits is the pinhole projection method, which produces a small image of the sun on a card.  Typical pinhole projection methods that show a partial eclipse so well are not as effective for transits because Venus is so small, requiring the projection screen to be much farther away from the pinhole to produce a large enough image.  This resource describes how to make an effective pinhole projector box for viewing the transit - make sure you get a long box!

You can also watch the transit online (even after the sun sets here in NC) - there will be several webcasts of the transit, including these offered by NASA and the Exploratorium.


What if it is cloudy the afternoon of the transit?

If it is raining of overcast, the transit observing session at GTCC will be cancelled.  If it is partly cloudy we will still try to observe.  Remember, if it is cloudy inthe Triad, you can still watch the transit in progress via the webcasts listed above.  Monitor the status of our session (and any Cline Observatory Session, including our regular Friday night public viewings) at our Twitter page @gtccastro.


Are there any other transit viewing sessions scheduled in the area?

UNC-Greensboro will hold a transit viewing session on the top floor of the Walker Avenue Parking Deck (weather permitting) from 6 p.m. until sunset.  They will also offer two Planetarium shows in the UNCG Planetarium in Room 310 of the Petty Building:  Monday, 4 June, 7:30 p.m., and Tuesday, 5 June, 3:30 p.m.

The Natural Science Center of Greensboro will hold a session from 5:30-7:00 p.m., weather permitting.

The Forsyth Astronomical Society will hold a transit viewing session at Pilot Mountain.