Frequently asked questions about eclipses

When a galactic event that doesn’t occur often happens, many people have questions.

According to NASA scientists, the following are some of the most commonly asked questions regarding a solar eclipse:

What causes an eclipse?

Eclipses occur due to the coincidence of the moon and the sun being the same angular size. The sun is 400 times wider than the moon, but it is also 400 times farther away, so they coincidentally appear to be the same size in our sky. This is what allows us the phenomenal beauty of the total solar eclipse.

How can I photograph a total solar eclipse using a camera?

You will need to purchase a solar filter that will reduce the brightness of the sun so that the light intensity does not destroy your camera. If you only take a photo at the moment of totality, you will not need this filter and will be rewarded by being able to photograph the faint corona, which will not be visible if you have the filter in place.

Most digital cameras with telephoto lenses of 100 mm or larger will show a disk for the eclipse that will show some detail. As a trial, photograph the full moon at night. It will be the same diameter as the total eclipse, so you can practice on the moon first to get the right telephoto lens combination.

Can I photograph the eclipse with my smart phone?

Yes, but you have to be careful that you minimize glimpsing the bright sun with your eyes without the benefit of a proper filter. As for your camera, there is no valid reason why you would want to point your smart phone camera at the brilliant, un-eclipsed sun without putting a filter over the lens.

Unless you have a telephoto lens for your smart phone, you will only be able to take un-magnified images of the eclipse in the sky. You will be able to capture the darkened disk of the moon surrounded by a clearly recognizable bright solar corona. If you use the camera’s digital zoom, you will see a pixelized, enlarged image that will not show much detail in the corona. To get around this, you need a telephoto lens for your smart phone.

Do animals really change their behavior during a total solar eclipse?

It has been reported during many eclipses that many different animals are startled by the totality and change their behavior thinking that twilight has arrived.

What are shadow bands?

These are among the most ephemeral phenomena that observers see during the few minutes before and after a total solar eclipse. They appear as a multitude of faint rapidly moving bands that can be seen by placing a white sheet of paper several feet square on the ground. They look like ripples of sunshine at the bottom of a swimming pool and their visibility varies from eclipse to eclipse.

The simplest explanation is that they arise from atmospheric turbulence. When light rays pass through eddies in the atmosphere, they are refracted. Unresolved distant sources simply twinkle, but for nearby large objects, the incoming light can be split into interfering bundles that recombine on the ground to give mottled patterns of light and dark bands or portions of bands.

Typically, how big a temperature drop do you get during a total solar eclipse?

It would probably be equal to the typical daytime minus nighttime temperature difference at that time of year and location on the Earth. It would be modified a bit by the fact that it only lasts a few minutes, which means the environment would not have had much time to thermally respond to its lowest temperature, so it would probably only be three-fourths or one-half of the maximum day/night temperature difference.

My house uses solar panels for electricity. Will they work during the eclipse?

No. As you get close to totality, you should notice a power drop in the output of your panels, which will reach a minimum when the sun is in full eclipse, and then your power levels will recover as the moon moves away from the sun.