John Chumack of Dayton, Ohio, took the picture on May 14th using a 10-inch telescope. "I was blown away by the sight of Venus," he says. "The planet was 14% illuminated, 47 arcseconds in diameter, and blazing at -4.43 magnitude."
The crescent shape of Venus is easy to see in good binoculars or small telescopes. No special observing experience is required. Just find Venus in the western sky after sunset (you can't miss it), point and look. A good tripod to hold the optics steady is recommended.
As the evening wears on and Venus sinks toward the horizon, the refractive effect of Earth's atmosphere splits the crescent into the colors of the rainbow. Kevin R. Witman of Cochranville, Pennsylvania, observed the phenomenon on May 11th: "Earth's atmospheric refraction of Venus's ample light made a beautiful image through my 10-inch telescope."
More images: from Mark Marquette of Boones Creek, Tennessee; from Philippe Vanden Doorn of Rixensart, Belgium; from Luis Argerich of Buenos Aires, Argentina; from Tomasz Gołombek of Tczew, Poland; from Francesc Pruneda of Palamós, Catalonia (Spain); from Sadegh Ghomizadeh of Tehran, Iran;