Later today people around the world will get a view of a transit of Venus. Such rare astronomical events take place when the planet’s orbit carries it directly between the sun and the Earth, allowing viewers to see it (as long as they use proper viewing equipment for safety!) as it appears to cross in front of the sun.
The transit won’t occur until relatively late in the day — it begins around 3 p.m. in Los Angeles — but astronomers already have their telescopes trained on Venus as the transit approaches.
The image of Venus above, for example, was taken Monday by Kevin Reardon, a researcher at the Arcetri Observatory in Florence, Italy, who is monitoring the transit from the Dunn Solar Telescope at the National Solar Observatory in Sunspot, N.M.
The photo, assembled from a number of high-resolution images, shows Venus as it nears its transit, at just two degrees from the sun — “about four full-moons away, which is pretty close (there is a lot of glare),” Reardon wrote in an email.
The bright part of the 360 degree arc, he added, is reflected light from the sun. The fainter part of the arc, opposite the bright portion, comes from light scattered in the upper atmosphere of Venus (“kind of like the scattered light in our sky after sunset”).
The arc will remain until the transit and may become more uniform in intensity as the transit approaches, Reardon said, and will appear in the days following the transit as well.