Observing Eclipses

The main thing about any eclipse is to get out and see it, so here's some information on the best ways to do that. Particularly in a brief total solar eclipse, you may well decide to just relax and enjoy the event, leaving photography to the experts; but if you'd like to have a go, there's some information on eclipse photography here too.

The first thing to remember about observing a solar eclipse is safety, so be sure to read about eclipse eye safety.

Solar Eclipses

Location, Location, Location...

If you're going to see a solar eclipse, the first thing to do is find a good place to see it from. For a partial solar eclipse, which is visible over a large part of the Earth, this should be easy; but more care is required if you want to get the best from a total solar eclipse.

You will see from the maps of total solar eclipses that the path of totality is quite narrow; if you're not in this zone, you'll miss the total eclipse entirely, and only see a much less interesting partial eclipse. You want to be close to the centre of this path to see a decently long eclipse -- you don't have to be right on the centreline, as the duration of the eclipse falls off quite slowly at first as you move away from the centre; closer to the edge, however, it drops much more rapidly. So, as a rule of thumb, be in the middle quarter or so of the path of totality.

Of course, a clear sky is essential, so try to get to a place with the least chance of cloud.

Finally, and this may sound obvious, pick a place with a good view of the sky where the Sun will be during the eclipse. Go there the previous day at the same time to see where the Sun will be, or work it out with a compass. If you're going to set up a solar projector (see below), a practice viewing the day before will help you to figure out the best setup. (And you might see Sunspots!)

One tip -- stay away from streetlights! Automatic streetlights may come on right at the moment of totality, which will spoil everything if you're under them.

So, once you're in place, what's the best way to view the eclipse safely?

Filters

Properly designed solar filters (such as eclipse viewing glasses), made and certified to appropriate national safety standards, can be used to look at the Sun during the partial phases of a total eclipse. Ad-hoc methods such as welder's goggles are not safe unless you know exactly what you're doing.

Pinhole Camera

The most recommended safe methods for viewing the Sun have one thing in common: they involve projecting the Sun's light onto some surface, so that the Sun is viewed indirectly. Be careful when setting these types of experiment up; the temptation to look through the setup to get it lined up must be resisted! The golden rule is that your back should be towards the Sun.

The simplest method is a pinhole camera. Make a small hole in a sheet of card, and hold it about a metre from another sheet of card, with your back to the Sun; the Sun's light will be "projected" through the pinhole and form an inverted image on the second sheet of card, which you can then look at safely. Don't look through the pinhole! You can adjust the size of the image by adjusting the separation of the cards.

Unfortunately, the image projected will be very small; just over 9mm for every metre of distance between the pinhole and the screen. You can improve on this by putting the screen a long way back from the pinhole, but you'll need to have lots of shade around the screen for the faint image to be visible. One idea is to put the pinhole in the window of a dark room, surrounded by curtains, or to use a tent. Making the pinhole bigger won't help -- it will just make the image blurrier. A small pinhole will give you a sharper image, albeit dimmer.

Solar Projector

A better technique is to project an image of the Sun using a telescope, or one side of a pair of binoculars. Place a sheet of cardboard around the objective (the big end) of the telescope or binoculars, to act as a shade for a second sheet positioned behind the eyepiece, about a foot away.

The whole thing should be adjusted by trial and error; you can adjust the focus by means of the focusing knob, and by moving the screen. Again, do not look through the binoculars/telescope! Line it up using its shadow on the screen; when the shadow of the telescope is a circle, it should be about right. You should cover or remove any finder scope to avoid temptation. Again, it might be a good idea to set up a large sheet of card or a blanket around the projector, to create a shaded area in which the projected image can be seen more clearly.

Setting this up can be a little fiddly, specially as the Sun is moving -- you will discover that the Sun actually moves quite quickly across the sky. Having a telescope on a tripod, and using a sunshade fixed to the barrel, should help.

Remember that you can experiment with the projection technique on any sunny day -- and this is a good way to look for sunspots! In fact, it's well worth trying out your Sun projector in advance of a total eclipse, to get the hang of setting it up.

Totality

Finally, the Sun during totality is a beautiful and spectacular sight; but don't be caught out by the end of the total period! Find out how long the total eclipse is going to be where you are, bearing in mind that a difference of a few miles can make a huge difference, and be prepared to look away at the first signs of the returning Sun.

Lunar Eclipses

Viewing lunar eclipses is easy and safe -- despite what some ill-informed people might say, as reported on the Bad Astronomy website. The Sun is safely below the horizon; above you in the night sky hangs the Full Moon, slowly being stained a dark red colour by the encroaching shadow of the Earth... Gaze and enjoy!

(In case you're wondering, the Full Moon is about 400,000 times dimmer than the Sun.)

The first thing is to get into a good place. Any night-time astronomy is greatly enhanced if you can get away from all the light pollution and smog in towns, so getting out into the country is a good idea; but having said that, a lunar eclipse should be easy to see from any back garden. With the eclipse being visible from the entire night side of the Earth, all you need is a clear sky.

No special equipment is needed; a lunar eclipse is great for naked-eye viewing. Dress for the night temperatures and take a flask of something warm.

Binoculars can help you to see the full beauty of the Moon, and can reveal a fascinating view of the lunar craters -- try looking at craters around the edge of the Full Moon.

Photography

Eclipse photography is a slightly tricky business, at least until someone has figured it out for you -- since other people have written about this far better than I can, I'll just point you to some resources.

The links below provide useful information on photographing and videoing an eclipse, including shutter speeds, filters, and so on.

Eclipse Viewing Links

Eclipse Observing

The Wendy Carlos Total Solar Eclipse Page

Very nice eclipse page by Wendy Carlos. Lots of fascinating eclipse photographs.

Sky and Telescope: Eclipses

Information page on eclipses from Sky and Telescope magazine, including great information on observing and photographing eclipses safely.

Eye Safety During Solar Eclipses

First and foremost: an essential guide to safety while viewing an eclipse.

Eclipse Photography

Sky and Telescope: Eclipses

Information page on eclipses from Sky and Telescope magazine, including great information on observing and photographing eclipses safely.

Lunar Eclipse Photography

Fred Espenak's guide to lunar eclipse photography.

Mr. Eclipse

Website dedicated to eclipse photography.

Eclipse Photography

Major list of eclipse photography resources, from Fred Espenak.

Solar Eclipse Viewing Products

Please note that I haven't tried any of these products, and can't vouch for the safety or suitability of any of them. These links are provided for information only; please ensure that any device you use for viewing the Sun has appropriate safety certifications. Buyer beware!

Rainbow Symphony, Inc.

"Rainbow Symphony, Inc., a recognized leader in the production of quality paper eye wear and specialty optical products, with a line of solar viewing devices."