More topic actionsEdit   Attach

Observing the Solar Eclipse


Do not attempt to observe the partial or annular phases of any eclipse with the naked eye. Failure to use appropriate filtration may result in permanent eye damage or blindness! The Sun cannot be viewed safely without eye protection. Sun glasses, telescopes or any other instrument not specifically designed for looking at the Sun will be dangerous to use. You should absolutely not use medical x-ray films, photographic film or smoked glass as filters. Even when 99% of the Sun's surface is obscured during the partial phases, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection.

How to observe a solar eclipse?

There are several safe methods that may be used to watch the partial phases.

  • The safest way is to project the image of the Sun produce by a telescope into a white scree (see figure). This technique has the advantage of allowing simultaneous observation for a group of people. Binoculars can also be used to project a magnified image of the Sun on a white card, but you must avoid the temptation of using these instruments for direct viewing. Projected images of the Sun may even be seen on the ground in the small openings created by interlacing fingers, or in the dappled sunlight beneath a leafy tree.
  • Another projection technique is to use a dark camera, in which a pinhole or small opening is used to cast the image of the Sun on a screen placed a half-meter or more beyond the opening. For that purpose you need a big box: First, make a small hole with a needle in one side of the box (n. 1 in the figure). It will be better to first cover this side of the box with aluminum foil. Then, make a larger hole in the opposite side of the box (n. 2 in the figure) and cover it with translucent paper. The light will enter to the box through the small hole and it will be projected into the translucent paper. Moreover, you could make a hole by the side to watch the image with higher contrast.
  • It can also be observed through a telescope, equiped with high-quality solar filters.
  • The Sun can be viewed directly only when using filters specifically designed for this purpose. Such filters usually have a thin layer of aluminum, chromium or silver deposited on their surfaces that attenuates ultraviolet, visible, and infrared energy. One of the most widely available filters for safe solar viewing is a number 14 welder's glass, available through welding supply outlets. More recently, aluminized mylar has become a popular, inexpensive alternative. Mylar can easily be cut with scissors and adapted to any kind of box or viewing device. There are also special solar glasses for observing the sun.
This site is powered by the TWiki collaboration platform Powered by Perl