In the shadow of the moon

IT’S not often that the narrow path of the moon’s shadow during a total solar eclipse crosses an easily accessible area, offering a chance for so many people to see the event.

But that was what happened on August 21 in the United States, where the much-anticipated eclipse did not disappoint.

It is often said that a total solar eclipse is the most spectacular sight that the human eye can behold. Having seen several of these events myself, I have to agree. In my opinion, there is nothing to beat it.

Clear skies were experienced along the path, about 100km wide, across many states of the US on eclipse day.

This fulfilled the hopes of so many: residents who were lucky enough to live somewhere within the narrow path, and others who had travelled, even from other parts of the world, to see the event.

During a total solar eclipse, the moon covers the sun completely for at most a few minutes. The inky-black silhouette of the moon appears to be surrounded by a beautiful, irregular glow, which is the sun’s atmosphere — called the corona. It is only during these events that the corona can be seen directly: it is because the brilliant glare of the sun itself is blocked. Changes in the corona mean no eclipse looks the same, and this is part of the excitement.

Friends of mine from Australia were watching from Oregon, having made the trip especially for the eclipse.

One of them excitedly emailed me to tell me of his success, although there was a little haziness in the sky at the time. A planetarium colleague in the US had a fine view from Idaho, and several places in the US east of there also had clear skies.

This has led to several questions from visitors to the Launceston Planetarium about such events seen from here in Tasmania. The most recent one for Tasmania was in May 1910, and the next one visible from here will be in June 2131, more than a century away.

The 2131 total solar eclipse will be visible from the far North-West Coast of the state, including Smithton, Stanley and Marrawah.

You will, therefore, need to travel to see one. They occur about every year and a half, on the average, and the next one will be in July 2019, visible from Chile and Argentina. The same countries are again favoured in December 2020, and Antarctica in December 2021.

So, how about Australia? We have several more this century, with the next one being on 20 April 2023, visible only very briefly from Exmouth in Western Australia. After three more in other parts of the world, our “big one” will be on July 22, 2028, when the path will cross right over the city of Sydney. It will be the place to be on that date.

Curiously, there were some very misleading media reports recently about the frequency of total solar eclipses. One source mentioned that the US had not seen one for nearly a century, but there have in fact been several. Another stated that there would not be another one for 45 years, but that too was incorrect.

It is important to always remember that looking at the sun can cause serious eye damage at any time, eclipse or no eclipse. Most solar eclipses from a given location are only partial, with part of the sun’s disc still visible. This is also the case as the moon gradually covers and uncovers the sun during a total eclipse.

It is especially important never to look through binoculars or telescopes at the sun, unless you have an astronomer with you using the correct professional equipment to remove almost all of the sun’s light.

The precious few minutes of totality, however, are safe and spectacular. If you get the chance to see one, make sure you know when it is safe to look. You’ll never forget the experience! Martin George is manager of the Launceston Planetarium (QVMAG).