Bert Halstead's Solar Eclipse Page

Bert Halstead's Solar Eclipse Page

I have had the opportunity to witness and photograph several total solar eclipses over the past two decades. All of these have been seen from distant lands, but excitement is now building for the total solar eclipse of August 21, 2017, which will cross the United States from coast to coast.

With that in mind, I have assembled this page of images and information about solar eclipses, which I hope will inform and encourage you to experience this grand cosmic spectacle.

This page contains sections about the dramatic experience of a total eclipse, how and why solar eclipses happen, where to learn about the upcoming August 2017 eclipse, photographing solar eclipses, the effect of the sunspot cycle on how total eclipses look, and finally a gallery of my images from eclipses that I have photographed.

The drama of a total eclipse

A total eclipse of the sun is the most dramatic celestial spectacle that most of us will ever have a chance to see. Like clockwork, the moon's jet-black outline inches across the face of the sun until the sun's light is completely blotted out. At that moment, we can see things that we never see any other time: the sun's glowing pink chromosphere, with flaming prominences leaping above the sun's surface, and the sun's feathery corona, with glowing white streamers heading out into space under the influence of the sun's magnetic field.

(All photographs copyright (c) by Bert Halstead, 1998-2012. Click on each image to see a bigger version.)

Partial phase of the eclipse. The moon is moving in from the lower right.
Three sunspots can be seen.
Egypt, March 29, 2006

Totality is just about to begin.
Prominences, the chromosphere, and Baily's beads can be seen.
Egypt, March 29, 2006

In the middle of totality, the sun's corona shows its beautiful structure.
Feathery streamers extend out into space.
Egypt, March 29, 2006

After literally just a few minutes, a brilliant point of sunlight reappears, creating the "diamond ring" that heralds the end of totality. The diamond is soon joined by Baily's beads: other points of sunlight that shine through low valleys in the moon's limb, and then the sun's light rapidly returns to the sky.

At the end of totality, a brilliant point of sunlight created the "diamond ring."
Egypt, March 29, 2006

When the sun shines through more than one lunar valley,
Baily's beads are created.
China, July 22, 2009

How do solar eclipses happen?

A solar eclipse happens when the moon passes between the sun and the earth, as shown in the following diagram from Wikipedia.

Geometry of a Total Solar Eclipse.svg
"Geometry of a Total Solar Eclipse" by Sagredo - Own work. Licensed under Public Domain via Commons.

Only if you are in the little black dot on the earth's surface (the umbra) will you see a total eclipse. For observers outside of that dot (in the penumbra), the moon does not completely blot out the sun, and only a partial eclipse is seen, as in the first of my images above.

As the moon moves in its orbit, the umbra of its shadow will move across the earth's surface. The umbra's small size is the cause of the rarity and excitement of a total solar eclipse. Only if you are located in a place that will be crossed by the umbra will you see a total eclipse, and even if you are located in the umbra's track, because the umbra moves along at more than 1000 miles per hour, the length of time for which you get to experience totality is never more than 7 1/2 minutes and is often less than four minutes.

If you aren't in the path of the umbra, you won't see the corona, prominences, diamond ring, Baily's beads, or any of the other phenomena shown in the images above, so the difference in your experience between 99% and 100% total is huge! Although a "good" total eclipse occurs once every few years somewhere on the earth, you probably will never see totality unless you travel.

Annular eclipses

As the moon travels in its orbit, it is sometimes closer to the earth and at other times farther away. Similarly, as the earth orbits the sun, in January it is a little closer to the sun and in July it is a little farther away. These differences cause small changes in the apparent sizes of the sun and moon as viewed from the earth. It can happen that the apparent size of the moon is less than that of the sun when an eclipse occurs. In this case, the umbra of the moon's shadow isn't long enough to reach the earth, and nobody sees a total eclipse. Instead, if you are lined up exactly along the line from the sun's center through the moon's, you will see an annular eclipse, in which the moon appears as a dark silhouette with a ring of sunlight visible all around it. This is an interesting spectacle in its own right, but does not give you a view of any of the dramatic phenomena that you see during totality.

Don't miss the August 2017 eclipse!

August 21, 2017, will be your chance to experience all this excitement without even needing to travel outside the U.S. The path of totality goes from Oregon to South Carolina, as seen in the following map, so there are many choices for where to observe it.

(Click to enlarge.)
Source: NASA

Here are some links that can help you get more information about the eclipse, including what time it will be seen in various places, and what weather conditions are most likely.

Photographing solar eclipses

The most familiar solar eclipse photographs are telescopic images of the eclipsed sun, such as my images shown above. But eclipses are accompanied by many interesting phenomena and can be photographed in many different ways.

This topic is discussed in more detail in my companion page on the subject, but I just want to acknowledge here that the telephoto views presented in this page are far from the only interesting way to treat the subject.

Solar activity cycles

The activity of the sun varies over a period of about 11 years from a maximum activity level with large numbers of sunspots, to a minimum level where sunspots are almost entirely absent. This is the solar activity cycle, also known popularly as the "sunspot cycle." The strength of the sun's activity also varies from one cycle to another, for reasons that are not understood. The most recent peak of activity was in 2014, but it was the quietest peak in more than 100 years.

One of the fun things about observing total solar eclipses is that the corona, chromosphere, and prominences never look the same from one eclipse to another, so you never know what you will see until totality arrives. In particular, prominences are much more numerous when solar activity is near a maximum, and the shape of the corona changes as well. These differences are visible in the images below, particularly when comparing the 1999 eclipse, which occurred near a solar activity maximum, and the 2006 eclipse, which occurred near an activity minimum.

I have had the opportunity to travel with members of the Amateur Telescope Makers of Boston to see and photograph five total solar eclipses over the past decade and a half:

  • February 26, 1998, in Aruba.
  • August 11, 1999, in Hungary. This eclipse occurred at a maximum of solar activity and featured an unusually large number of impressive prominences.
  • March 29, 2006, in Egypt. The dry desert air gave us the best observing conditions of any of the eclipses that I have seen. Several images of this eclipse appear at the top of this page; an album containing a few more can be found here.
  • July 22, 2009, in China. A collection of images from this eclipse can be found here.
  • November 14, 2012, in Australia. Unfortunately we were almost completely clouded out for this eclipse.
Additionally, I was able to photograph the annular solar eclipse of May 21, 2012, while traveling in Japan.

Gallery of eclipse images

The period from 1998 to now has seen major changes in photographic technology, as well as in my skills and in the equipment that I have taken to the eclipse sites. The 20th century pictures were taken on color slide film, while the more recent images are digital. Because of my learning curve and more primitive setup, the earlier images are unimpressive compared with the more recent ones, but they are still interesting because they illustrate the many ways an eclipse can look.

1998 eclipse

The February 1998 eclipse occurred close to a solar activity minimum, which is characterized by few prominences and by a corona structure featuring expansive streamers at the solar equator and not so much activity near the poles. I have one good image to post here, which illustrates how the streamers are noticeably longer in the equatorial direction (which in this image runs from the top left to the bottom right) than in the polar direction.

The sun's corona with long equatorial streamers.
Aruba, February 26, 1998

1999 eclipse

The August 1999 eclipse occurred near a solar activity maximum, so it had many spectacular prominences and a much more ragged corona shape with streamers extending in all directions. Here are several images with different exposures. The images with the shorter exposures show the chromosphere and prominences, including a spectacular "hanging prominence" at about the 3 o'clock position. The longest exposure is too long to show the prominences, but shows more of the shape of the corona.

Short exposure showing chromosphere and prominences.
Hungary, August 11, 1999

Longer exposure showing the brightest parts of the corona.
Hungary, August 11, 1999

Still longer exposure showing corona all around the sun.
Hungary, August 11, 1999

Longer exposure showing the beginnings of coronal streamers.
Hungary, August 11, 1999

Longest exposure showing the structure of the inner corona.
Hungary, August 11, 1999

Diamond ring at the conclusion of the eclipse.
Hungary, August 11, 1999

2006 eclipse

The March 2006 eclipse marked my transition to digital photographic technology as well as the use of a tracking mount that followed the motion of objects across the sky. These two improvements led to a big improvement in quality. As can be seen from the above images of the 1999 eclipse, the range in brightness of eclipse phenomena is enormous. The chromosphere and prominences are as much as 4000 times brighter (12 photographic stops) then the faint outer reaches of the coronal streamers. This is a much bigger range brightness than standard photographic technology can handle. With this eclipse, for the first time, I was able to use HDR ("high dynamic range") techniques to show the whole structure of the corona in one image. This image has already been included above, but here it is again:

In the middle of totality, the sun's corona shows its beautiful structure.
This image was produced using HDR techniques from a set of 8 exposures
ranging from 1/60 second to 8 seconds.
Egypt, March 29, 2006

We can see that the corona is back to its solar minimum shape, with long equatorial streamers and shorter "polar brushes."

2009 eclipse

The July 2009 eclipse was observed through a fairly thick haze that limited the visibility of the outer corona, but applying the HDR techniques led to the following image:

Corona for 2009 eclipse, processed using HDR techniques.
China, July 22, 2009

Several other images can be found on a page dedicated to this eclipse.

2012 annular eclipse

The May 2012 annular eclipse, while not as spectacular as a total eclipse, was interesting in its own way, so I have included a few pictures of it. This eclipse was seen through clouds, which added some drama to the images.

Shortly before the beginning of annularity.
Japan, May 21, 2012

View through clouds in the middle of annularity.
Japan, May 21, 2012

The moment at the end of annularity, showing a few Baily's beads.
Japan, May 21, 2012

2012 total eclipse

Bad luck finally caught up with us in our attempt to see the 2012 total eclipse, as a stubborn bank of low clouds almost completely blocked out the sun. There were just a few opportunities to glimpse totality and the corona through thin spots in the clouds. The images below will give an idea of the experience.

Partial eclipse before totality.
Australia, November 14, 2012

Moments before totality, part of the corona can already be seen.
Australia, November 14, 2012

Chromosphere and prominences, viewed through thick clouds.
Australia, November 14, 2012