Wednesday, 28 December 2016

Almost 2017

It has been a long time coming! When the 1970 TSE skimmed along the Eastern coast of the USA a small group went from the local astronomy club. They achieved success and the report they gave inspired my own family to make plans to see one.

Ted Pedas (talking) talking with my mother in 1972

We went, in 1972 and again in 1973, traveling with Ted Pedas and his Voyage to Darkness crew. It was, in a nutshell, a lot of fun, a grand experience, educational, and worth doing again. But not worth skipping school it turned out. In 1979 I did not go as I was in college and going would have interrupted school at a critical time. And that was the last time a total solar eclipse fell across the continental USA.
USA 2017 Eclipse Path -

The next one would not be until 2017 - and that is almost here!

I have been to numerous other total solar eclipses, 16 in fact. They really are something worth seeing again and again. My wife and kids have come along and enjoyed the experience too. We are a family of eclipse chasers!

This year we bring a new member along. A grandson named Finn. While less than a year old (born in November), he won't remember anything of the event, but he will have the bragging rights at sometime in the future! Why not start young?

Finn rocking to some serious music

Monday, 19 December 2016

Greatest Eclipse - a strange term

You may have noticed the term Greatest Eclipse appearing on some maps of the total solar eclipse path. Perhaps you already know what that means.

Recently, some questions came up related to this term in the SEML, an open discussion group of eclipse enthusiasts. My initial reaction was to try to define the terms being used [see previous blog entry] but after further consideration and some guidance from some great minds I am revising my feelings.

The term is meaningless for total solar eclipse chasers unless one wants to say they are at the best place for syzygy.

Syzygy is the alignment of three astronomical bodies such as the Sun, Earth, and Moon. During perfect syzygy an eclipse takes place.

So if you want to experience the greatest syzygy, then the Greatest Eclipse point is the place to be!

The term "greatest eclipse" indicates that the cone of the lunar shadow is closest to the center of the Earth. For a total solar eclipse this point is somewhat near the center of the central path. It all depends on the inclination of the Earth to the Ecliptic, latitude of the observer, and so on. Really, it is not the greatest point to see the eclipse, but it is normally a good one - if the sky is clear.

For a partial solar eclipse, the greatest eclipse point is where the maximum eclipse coverage will be seen. So for that context, a partial solar eclipse, the point makes sense. But it really does not hold much interest for total solar eclipses. Especially if compared to duration which is very important for some.

Seeing a total solar eclipse is not about the amount of time you see one. No matter how many minutes the total eclipse is predicted to last, it will seem like just a few seconds. There are those who have seen over two dozen eclipses that will tell you that every eclipse seems to last about 15 seconds. The key thing is to see it! It really is a surreal experience. Once you see one, you know, and then you might want to add more time by going to another and another. Some of us keep on going, we can never get enough! See the eclipse-chasers log. Only a few have reached over a half hour of total eclipse observing!

I often tell people that as an amateur astronomer I can stare at the Moon or Saturn or Jupiter for hours and not get bored with the view. They are amazing to behold themselves. A solar eclipse - well, I have seen just under one hour of totality so far. I've looked at Saturn longer than that in a single night! Truth is, once you see one, you want to see another one.

Friday, 16 December 2016

Greatest Eclipse and Longest Duration

There is a point of confusion for many interested in eclipses. The term "Greatest Eclipse" appears on many eclipse maps. So does that mean it is the greatest place to see the eclipse? Or maybe the longest duration point of the eclipse path? Or maybe something else?

The term "Greatest Eclipse" is, in my opinion, a poor choice of words to describe a geometric point, one that is calculated. But one is pressed to come up with a better term and thus we keep using it. And every eclipse we need to clarify just what that means. So here goes....

Just for clarity, we are only talking about total solar eclipses and not annular or partial, although the same term applies in both (see Types of Eclipses). I want to focus on totality only since that is the "big show". Annular and partial eclipses are nice, but they are not really spectacular like a total solar eclipse.

The greatest eclipse point is where the shadow of the moon (a cone shaped shadow) is nearest to the center of the Earth. It is a calculated point using the geometry of the eclipse. This point may just coincide with the longest duration and could even coincide with the best place to be for an eclipse - but that is not always the case.

The longest duration is a function of the elevation, angle of the Earth towards the Sun, lunar profile and so on. Many times the greatest duration is found near to the Greatest Eclipse point, maybe just a few kilometers off. The computation of the greatest eclipse point is direct, the computation of the greatest duration is iterative. That means we calculate a heap of points to find the longest duration.

For example, this summer's eclipse across the continental USA, note that the Greatest Eclipse (in green) is east of the Greatest Duration (magenta). Map courtesy of NASA.

So where exactly is the really greatest place to see the total solar eclipse? Where ever the sky is clear at the time of totality! Oh, and inside the narrow path as seen in the map above!

Monday, 12 December 2016

Eclipses from the Air and Sea

I recently updated the Eclipse-Chasers.Com web pages for the lists of intercepts in the air and at sea. If you know of any other eclipse flights and cruises, please let me know so I can add them in.

List of Eclipses seen from Aircraft

List of Eclipses seen from Ships

It is unlikely there will be many opportunities to catch the TSE 2017 event from the air or sea, but that remains to be seen. When mobility is important, these two options offer the best chances to get under clear sky (or above the clouds).

Saturday, 3 December 2016

AAS 2017 Eclipse Web site

The American Astronomical Society (AAS) has put together a website related to the total solar eclipse in August 2017. A very well structured site for those looking to learn the basics and get good information going forward. It contains maps and articles from other websites with links for those wanting to know more. And you might even be able to apply for a small grant to help fund your solar eclipse chasing, that is if you have something science related to add. They won't pay you just to see it! is Highly recommended!

Here is an announcement from Dr Richard Fienberg, press officer of the AAS. Just part of the press release. A link is provided for those wanting to know more.

The American Astronomical Society (AAS) has launched a new website,, to help prepare the country for next year’s most anticipated celestial spectacle: the first total eclipse of the Sun to touch the US mainland since 1979 and the first to span the continent since 1918. With support from the National Science Foundation (NSF), the AAS has also unveiled a program of small grants to fund educational activities aimed at engaging the public with the eclipse.
Several excellent solar-eclipse websites already exist thanks to the efforts of a handful of individual amateur and professional astronomers as well as NASA. “Rather than ‘reinvent the wheel,’” says Shadia Habbal, co-chair of the AAS Solar Eclipse Task Force, “ offers a modest amount of high-level information to get people started and then provides links to more detailed information on other sites. It’s a curated guide to the best and most reliable resources on solar eclipses in all media.”

The AAS has been hosting a set of conferences preparing for the eclipse. Local governments, police, community leaders, and others have been invited to the conferences to get information to help them prepare for the upcoming eclipse. These conferences have been highly successful in getting the word out in a correct way. One of the common requests at the conferences was to have a comprehensive web site and they have delivered. Great job folks!