Solar Observing

Our home star presents opportunities for observing every sunny day.


The easiest safe way to observe the Sun through a telescope is to project the image. This works best if you have a small, inexpensive refractor telescope like the one shown below.

*Note: It is recommended that you use inexpensive eyepieces with two elements for projection. Eyepieces with multiple elements may trap the Sun's heat and crack.*

 Projection can also be used with most reflector telescopes, although the set-up is trickier. To avoid damage to your mirror or lens, minimize the amount of time the 'scope is pointed at the Sun.

Solar Filters are another way of viewing the Sun. A filter fits over the front of the telescope and allows only a very small percentage of sunlight to filter through. Make sure you buy from a reputable manufacturer. Do not use the "Sun Filters" that are sometimes supplied with small telescopes. These filters, which screw into the eyepiece, are prone to breakage, with disastrous results. Get a glass or mylar filter that covers the entire aperture of the scope. Also remember to cap your finder scope when viewing the sun and to carefully supervise any telescope being used for group solar viewing.

What can you see on the Sun? The Sun's face is ever-changing. Over periods of days, sunspot groups rotate in and out of view. The number of sunspots varies as well. Large sunspots can be differentiated into a dark center (umbra) and a gray outer region (penumbra). Bright patches are called faculae and are often glimpsed near the solar limb, which appears darker than the rest of the Sun. You may also notice that the overall texture of the solar image is mottled. This is referred to as the solar granulation.

Other features, such as solar flares and prominences, are not easily viewed. A special filter, called a Hydrogen-alpha filter, isolates the light from these features and brings them into view. H-alpha filters are available on the market, but are quite expensive.

Sketch of Sun through Hydrogen-alpha filter

A solar eclipse occurs when the Moon's disk passes in front of the Sun as seen from a particular place on Earth. A partial solar eclipse occurs when only part of the Sun's light is blocked. These eclipses are fun to view with projection devices. When the whole solar disk is covered by the Moon, a total solar eclipse occurs. During totality, which usually lasts for a few minutes at most, the usually-invisible outer parts of the Sun's atmosphere become apparent. Contrary to popular belief, it is not dangerous to look at the totally eclipsed Sun with the naked eye. During the partial phases, the Sun has its normal blinding potential. Schools that keep children inside during eclipses ought instead to have projection boxes and filtered telescopes set up to allow kids to experience these educational events. One or two solar eclipses occur in most years, but are visible from only small sections of the globe. In any one location, many years will pass between total solar eclipses.

© Copyright Info.