Observing the Sun Safely

To look at the Sun you need special equipment.
NEVER look at the Sun through a standard telescope or binoculars—you will seriously damage your eyes.

Observing Methods

There are four common ways to safely look at the Sun. These are detailed below. In my daytime astronomy sessions I use the first three methods regularly, and occasionally I use the projection method too.

(1) Eclipse Glasses

This is one of the simplest and cheapest way to get a good look at the Sun with your own eyes. Eclipse glasses are designed to look at the Sun during a solar eclipse but you can use them any time. Unfortunately you won't actually see very much—the Sun will appear as a white circle against a very dark background. It appears to be the same size as the Moon, so it's rather like looking at the Moon with no surface detail—just a white surface.

Reflector telescope with solar filter.
For safety, the finder scope has been removed.

(2) Solar Filters

The next best thing is a solar filter attached to a regular telescope (pictured right). This will reveal sunspots and maybe some other surface features, but probably not a lot of detail. Typically you'll see the Sun as a white circle with a few small black spots on it.

The big issue with this method is safety. Please follow these guidelines...

• Only use an approved solar filter designed for use with a telescope.
• Do not use sunglasses, Polaroid filters, tinted glass, x-ray film, or neutral density filters.
• Do not use filters that fit on the eyepiece. Only use filters that block the light before it enters the telescope. Sun filters that go on the eyepiece should literally be destroyed on sight (seriously, they're that dangerous).
• Make sure the filter cannot be easily removed by people using the telescope. I've heard stories of members of the public trying to pull off a solar filter as a "joke".
• Don't forget about the finder scope. Some people will try to look through it without warning, so cover or remove it.
• Keep an eye on the temperature of the telescope. It should not get hot.

Lunt LS60THa solar telescope.

(3) Solar Telescopes

Solar telescopes are purpose-built for viewing the Sun, so they are very safe and effective. These telescopes are filtered and tuned to the exact wavelengths of light to see all the glorious details on the Sun's surface. You'll be able to make out sunspots, filaments, flares and prominences.

(4) Projection Methods

Instead of directly viewing the Sun through an eyepiece, you can project the image onto a white surface such as a piece of cardboard. You can do this either with a normal telescope or by making a pinhole camera. Personally I've found this method to be less than satisfying, which is why I rarely do it and I have no photos or detailed instructions. Sorry.

Aligning the telescope

One quick way to get your telescope pointing at the Sun is to use its shadow. Simply move the telescope around until it casts a more-or-less circular shadow. Often you'll never actually get a circle—you just need to find the angle that casts the smallest shadow.

That should be enough to see it in your eyepiece and fine-tune the view.

If you need to hunt for the Sun using the eyepiece, be aware that it's not easy. There is no tell-tale glow as you get near to it. The view will be black until the Sun suddenly enters.

Another method is to use an attached solar finder. Televue makes a nice little unit called Sol-Searcher. I have one of these on my Lunt telescope and it's fantastic. It's quite cheap and highly recommended.

DO NOT use any method that involves looking towards the Sun. You should always be able to align the scope by looking away.

In Conclusion...

Solar observing is very rewarding, and simple viewing methods can be achieved very cheaply. Unfortunately the good views are very expensive and you need to think hard about how much you'd use a solar telescope before fronting up with that much money. You may prefer to contact your local astronomical society and see if there are any local telescopes open to the public (of course, if you're in New Zealand you can contact me).

In any case, the main thing to remember with solar observing is safety. This is a serious business. If you're using home-made equipment, a momentary lapse in concentration can result in blindness. Let's be careful out there.