I recently came accross the following:
Try the pinhole experiment. Make a large pinhole about 1 inch
from any corner of an index card, tape two pencils on the outer
edge so the card can be raised from laying flat, then tape a blank
white side of another index card to the first card so that the
cards are about 3/8 to 1/2 inch apart. Hold the pinhole perpendicular
to the sun, on a sunny day, and look carefully between the two
cards. You will see two circles of light, not one! The second
is not as bright as our Sun, and should be about 1.5 diameters
of our suns dot away from it. This distance is changing and therefore
indicates the second sun is slowly widening the distance between
the two, as observed from our vantage point on Earth.
What do think is going on here?
I think that what's going on here is a bit of crackpottery. (unfortunately, you can find a lot of that on the net... :)
Have you done the experiment yourself? I doubt you would see such a second "Sun." An object like that which is bright enough to appear in a pinhole camera should also be very visible to the naked eye, and I only saw one sun on my way to work this morning.
Answers provided by HSU Astronomy Professor David Kornreich.