Title: Solar diameter with 2012 Venus transit Authors: Costantino Sigismondi
The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides.
A brief simulation of the June 6th 2012 transit of the planet Venus in front of the Sun as seen from NASA's Solar Dynamics Observatory, the last one to occur in our lifetimes.
NASA EDGE promotes their live coverage for a major, unique and predictable astronomical event in 2012! NE Live@Transit of Venus 2012 Promo.
The next transit of Venus will occur on June 5--June 6 in 2012, succeeding the previous transit on June 8, 2004. After 2012, the next transits of Venus will be in December 2117 and December 2125.
Transit of Venus, 6th June, 2012
Seen from Adelaide, South Australia, here is an animation of the Solar Transit of Venus in 2012. The animation was made using the Astronomical Planetarium program, Stellarium.
The next transit of Venus is only one year away! This will be the very last opportunity for us to witness one of these rare events from Earth. By the time the following transit occurs, a next generation is pointing its telescopes to Venus and the Sun. So, the transit of Venus on June 5 and 6, 2012 is certainly an event not to be missed! Read more
Due to its slightly tilted orbit with respect to Earth's, Venus crosses between Earth and the sun on an oddly spaced cycle. Transits come in pairs spaced eight years apart, but the time between pairs is 122 years, then 105 years. Due to this pattern, only six Venus transits have been seen since the invention of the telescope. A Venus transit in 2004 was the first of a pair. Before that, the most recent transit had been in 1882 - which means no living people on Earth had seen a Venus transit when the 2004 event occurred. Read more
The next transit of Venus will occur on June 5-June 6 in 2012, succeeding the previous transit on June 8, 2004. After 2012, the next transits of Venus will be in December 2117 and December 2125. Read more
The transit will be best viewed from the Pacific Ocean. North America will be able to see the start of the transit, while South Asia, the Middle East, and most of Europe will catch the end of it. The transit will not be visible in most of South America or western Africa. Venus starts to cross the solar limb at interior egress at 04:37 UT, and the transit ends with exterior egress at 0:55 UT. The transit of Venus will not be visible in its entirety from the British Isles. The latter stages of the transit will be in progress during sunrise and ends between one and one and a half hours later depending on your location. Sunrise for Edinburgh, Scotland, is at 03:30 UT.
TT and Type Sun Min Sun Ven of Greatest Transit Duration RA Dec Sep Rad Rad hh:mm h ° " " " AD 2004 Jun 08 08:21 C 06:18 5.19 0.00 626.9 945.5 28.9 AD 2012 Jun 06 01:31 C 06:44 5.05 -0.00 554.4 945.5 28.9