On the afternoon of June 5, people across North America will have a chance to see Venus pass in front of the Sun for the second and final time this century. Our sister planet previously crossed the solar disk eight years ago, in June 2004, but it won’t do so again until December 2117.
Although such transits are rare, more than three-quarters of the world’s population will have an opportunity to see at least part of this year’s event. Observers with clear skies can witness its entire duration from eastern Asia, eastern Australia, and the western Pacific. For those in North and Central America and northwestern South America, the transit’s early stages will be on display before the Sun sets June 5. Inhabitants of central and western Asia, western Australia, eastern Africa, and most of Europe will see the transit’s closing stages after sunrise June 6.
Before you look at the Sun during the transit (or at any other time, for that matter), make sure to protect your eyes. Even without optical aid, sunlight can burn your retina in seconds; looking through binoculars or a telescope can blind you almost instantly. For a naked-eye view, use a #12 or #14 welder’s glass or “eclipse glasses” specifically designed for viewing the Sun. Both block dangerous ultraviolet and infrared radiation as well as visible light.