The Sun can be dangerous to look at. Only during the total phase of a total eclipse can one safely look in the direction of the Sun since the Sun's disk is no longer visible. At this time the Moon's disk completely hides all parts of the bright solar disk. (Exception: Sometimes the Sun is OK to briefly look at with the naked eye when the Sun is just rising or setting.)

Under what circumstances can one safely look at the Sun without any protection? (Click image for answer.)

Solar Filters

Although several reputable companies manufacture solar filters that can be used to safely photograph or view the Sun's disk, most filters easily available to the public are not safe to use for viewing the Sun. In addition, improper use of even a safe solar filter can damage eyesight.

Several companies sell safe solar filters for visual, photographic or other uses. The following lists links to companies that make solar filters including articles about eye safety and observing the Sun:

	Baader Solar Film	Baader AstroSolarTM Safety Film from Baader Planetarium
	A Beginners Guide to Solar Observing	How to safely study our star by Sky & Telescope
	Close-Up of Star	Here's what to look for on the solar surface by Sky & Telescope
	Coronado Filters	Specializes in H-alpha filters & solar viewing instruments
	DayStar Filters	A leading manufacturer of solar filters incl. H-alpha filters for professionals & amateurs
	Eye Safety & Solar Eclipses	By expert B. Ralph Chou, M.Sc., O.D., Assoc. Prof., School of Optometry, Univ. Waterloo (From NASA's Reference Publ. NASA/TP—1999-209484)
	Observing Eclipses Safely	Adapted from Chp. 11–Totality: Eclipses of the Sun by Mark Littmann, Ken Willcox & Fred Espenak
	Observing the Sun by Projection	Safe ways to study solar events by Sky & Telescope
	Rainbow Symphony	Produces safe solar shades
	Solar Filter Safety	An article on eye safety and filter by Sky & Telescope
	Solar Filter Suppliers	A list of solar filter vendors by Sky & Telescope
	Thousand Oaks Optical	Manufacturer of safe solar filters.

• Filters made from sunglasses, Polaroid filters, smoked or dark glass, typical photographic neutral density filters, CDs, floppy disk media, cellophane and mylar food packaging, undeveloped film, color films, slides or negatives, X-ray films with images, and chromogenic photographic emulsions are not safe! These filters may transmit dangerous amounts of ultraviolet or infrared radiation even if the filter appears opaque. They may also have small pinholes or non-uniform coatings that can allow unsafe amounts of light through.

• Common neutral density filters sold in most photographic stores that may me OK for photographic use may not be necessarily safe for visual use when you look through the camera's viewfinder! (The filter may still transmit unseen ultraviolet or infrared rays.)

• Welder's #14 glass may be OK but produces a greenish color and poor image quality.

• Filters, of any type, designed to be placed at the end of a telescope or binocular (e.g., on an eyepiece) are not safe. (The Sun's heat may crack the filter.) Throw them away!

Projection Method

A simple and safe method for observing the Sun is by pin hole projection. This produces a small but safe image to view. See diagram below. Notice that the observer looks at the projected image — do not look through the pinhole!

Project the Sun's image —do not look through the pinhole at the Sun
(Click image to enlarge)

Any object that produces small pinholes will project the Sun's image. For example, the separation between leaves on trees will project numerous, small images of the Sun on the ground!