A rarely seen transit of Venus across the face of the Sun will occur on Tuesday, June 5, beginning at 5 p.m. The next one won't occur until 2117, so take advantage of a free, safe telescopic viewing of the transit hosted by the Champaign-Urbana Astronomical Society and the William M. Staerkel Planetarium.
If the weather permits, telescopes equipped with special filters will be set up just west of the perimeter drive, south of the Tony Noel Agricultural Technology Applications Center on the Parkland College campus. The public is invited to park in the C-4 parking lot on the west side of campus just south of the planetarium and then walk to the telescopes.The event starts at 5:09 p.m. and will last roughly six hours. Venus will appear as a black dot in front of the Sun. From our location, the Sun will set before the transit is over. One should never look at the Sun without appropriate protection; sunglasses do not supply such protection! You may use special eclipse glasses, #14 welder’s glass, special white light Mylar filters, or solar projection.
The Earth and Venus are on the same side of the Sun every 584 days but, due to the four-degree tilt of Venus’ orbit, the planet rarely treks across the face of the Sun. There have been only six transits since the invention of the telescope. In the 1700s, a transit was used to find the distances to the other planets. One can find these distances using Kepler’s Laws if you know the Earth/Sun distance, a number that wasn’t accurately known until a transit of Venus. Transits come in pairs, with the last event occurring in June 2004. After the June 5 event, the next transit will occur in December 2117.
Image from www.timeanddate.com