No one reading this will still be alive the next time Venus crosses the sun in 2117. That makes today special. On June 5th at 3:09 pm PDT, the second planet begins its historic 7-hour transit of the solar disk. Below follows instructions on how to observe the Venus passage safely (:
If you’re thinking of viewing the Sun, your first concern should always be eye safety. Serious eye damage can result from even a brief glimpse of our star — Galileo looked at the Sun through a telescope 400 years ago and suffered permanent eye damage. If it happened to Galileo, it can happen to you!
One safe way to observe sunspots or eclipses is to project an image of the Sun through a telescope or binoculars onto a white screen — paper plates, walls and sidewalks all work nicely. If you’re using a telescope, be sure that any small finder telescope is capped. If you’re using binoculars, keep the cover on one of the two tubes. Never look through a telescope or binoculars to point them at the Sun — partial or total blindness will almost surely result.
On the screen you should see a bright circle of light. This is the disc of the Sun. Adjust the distance between the screen and the telescope until the disk is about the size of a small paper plate. The image will probably be blurred; focus your telescope until the circle becomes sharp. Using this method you can see considerable detail in and around sunspot groups.
Tom Hanson of Murray, Utah, suggests this variation on the binocular projection technique: darken the room and add a mirror. “When I look at sunspots I use binoculars, but instead of putting a piece of paper under the binoculars, I put a mirror under it and project the image on a wall,” says Tom. “The image of the sun is not as bright, but the diameter of the sun’s image is about 6 feet depending on the distance from the mirror to the wall.”
He continues: “I also close the blinds in my house except for an opening for the binoculars to pick up light. This way the darkened room allows for much more detail to show. The smaller spots and minor details can also be seen with excellent detail.”
Pinhole projectors and certain types of solar filters can also afford a safe view of the Sun. Pinhole projectors usually produce a small and unsatisfying image, but they are better than nothing if you don’t have a telescope or binoculars.