Transit Observing Plan

THIS IS A WEATHER DEPENDANT EVENT:  Cancellations will be posted by twitter feed at  

The transit of Venus on 5th June will be the last opportunity to see such an event until 2117.  It is therefore a last-chance-of-a-lifetime event for us.  It occurs as the sun is setting. Event timings are as follows for our location:

  • First Contact:                        6:04PM EDT         Venus’ edge appears on sun’s face.
  • Second Contact:                   6:22PM EDT         Venus’ complete disk is visible on the face of the sun.
  • Sun Sets Behind Trees:       7:40PM EDT         Transit viewing effectively ends for us.

A simulation of the event is available online at this address:

Information for other locations is available at:

Our observing location will not be at the observatory, as that location has blocked westerly views. We will be setting up a portable observing site at the fields across from the observatory on the extreme eastern side.


It is NEVER safe to observe the sun without proper filters. Observing the sun without safe filtration will damage the human eye immediately and irreversibly. We will have telescopes with proper filters available for you to observe safely. We will also have a telescope for imaging the event in coordination with other sites to use for scientific research.

More Information:

Please go to for more information about this event and the Academy’s astronomy program as a whole. You can also go to for last minute announcements.

Venus Nearing Transit

I had a few spare moments around the observatory last night. The Sun was still lurking just above the western horizon, the dome was open, cooling off, and a thought entered my mind: hey, I bet Venus is visible through those trees!  Exeter is a small town, and the observatory is crammed into a small section of Academy fields on one side, the river and town on the other two sides. Trees block the western view, but in this case a little luck dropped by.

Slewing the telescope over to the west, there was Venus, easily visible in broad daylight. I took a quick peak through the eyepiece: wow, a perfect crescent, and that made perfect sense. Venus is headed into transit on June 5th: it will become an increasingly thin crescent until that magic moment of transit.  Not wasting a minute (I was really bustling in the dome to get this to work out), I found a webcam and some extra long USB cables and took the following. Enjoy! This is through a Celestron SCT using a ToUCamII Pro. Registax was then used to stack 1000 images for the final shot.

venus 18 May 2012

And for those interested in the raw footage, here it is: If you listen carefully you can here the drone of the Paramount telescope drive system and some mumblings by yours truly as the seeing conditions got worse. 😉

A Word of Observing Caution

UPDATE:  The NHAS has posted their preliminary observing locations and maps:

This June 5th, we have an opportunity to see a rather rare astronomical event, the transit of Venus, when the planet Venus gets between our Earth and the Sun. The result is that we can see the small, round dot of Venus’ silhouette traversing across the bright disk of the Sun. This event has both tremendous scientific and historic significance in astronomy, but it also has its dangers.

The Sun is bright, something we all know. We shouldn’t look at it without proper protection, namely solar filters. One should definitely NOT look at the Sun through a telescope unless one employs a full aperture solar filter which has been approved for visual solar observing. Failure to adhere to this warning means instantaneous and irreversible damage to your eyes.

  • Do not employ dark glass for a solar filter.
  • Fogged film is not an appropriate solar filter.
  • Dark sunglasses are not appropriate solar filters.
  • Welding glass used at the eyepiece of a telescope is NOT a safe solar filter.

If you are interested in seeing the transit using safe equipment, and you are not sure what to purchase, you have some options:

  • Visit your local astronomical society or planetarium and ask the astronomers there for equipment suggestions.
  • An affordable solution to see the transit without optical aide would be to purchase some “Eclipse Glasses” from a source like Amazon. This one comes in a package of 5:  HERE.  WARNING!!!  DO NOT USE THESE IN COMBINATION WITH BINOCULARS OR OTHER UNFILTERED OPTICAL SYSTEM. These cannot withstand the light and heat concentration put out by optical instruments. These are for wearing alone.
  • Many local astronomy clubs, societies and associations will be setting up equipment for the public to use in order to view the event. The New Hampshire Astronomical Society is doing just that and will post information at as they prep for multiple observing sites throughout the state on the afternoon of June 5th.
  • From the east coast (New Hampshire), the Sun will be setting as the transit begins. Some observatories, including the one at Phillips Exeter Academy will not be able to see the Sun through trees and houses which will obstruct the view. In these cases the observatory will remain closed, and a portable observing location would be set up elsewhere at a higher elevation with a clear westerly view. Stay tuned to your local club’s/observatory’s websites for more details.

Historical Significance:

Transits were one of the earliest observational methods used to determine an accurate measure of the Astronomical Unit, the average distance between the Earth and the Sun. Using two widely separated observing stations and precise timepieces, observers would note the time difference between the start and end of the transit. Using then the mathematics of triangles (parallax) and Kepler’s Laws of Planetary Motion, the distance could be calculated.

The earliest observation of this type actually involved the planet Mercury transit of the Sun in 1676. A rather famous astronomer (you know the name!), Edmund Halley, made observations from St. Helena. One other set of observations was made elsewhere, but the mathematics proved to show some serious inaccuracies. In 1761 (and by this time Halley had passed away), there was a Venus transit. Many sites were established to observe the event. In 1769, another Venus transit was observed, and also created a large scientific collaboration between countries. This was also the first event which marked Captain James Cook’s initial voyage through the Pacific. Future transits were then observed, the last in 2004. The next one will be in 2117 (December 10-11), so this event in June 2012 will be the last we are able to see in our lifetimes.  To help you plan your transit, see the two images below. The first is from the Wikipedia article Transit of Venus, 2012. The second comes from the NASA Eclipse Website.