THE SOUTHWORTH PLANETARIUM
207-780-4249       www.usm.maine.edu/planet
70 Falmouth Street  Portland, Maine 04103
43.6667° N,                    70.2667° W
Founded January 1970

                  "17. Better a waterfall than a stagnant pond."

 

 

THE DAILY ASTRONOMER

Tuesday, May 10, 2016

Now, About Next Year's Solar Eclipse

 

We just finished droning on about one astronomical event and, now that the Mercurian transit belongs to the ages, we promptly shift to another beautiful celestial event: next year's total solar eclipse.    In our defense, the August 21, 2017 total solar eclipse will likely be the most widely viewed eclipse in history.    After all,  it will be the first total solar eclipse visible in the continental United States since 1979.   Secondly, the totality path will extend from the country's Pacific coast to Atlantic coast.  A totality path has don't that for almost a century.    Consequently, this eclipse will be so hyped and overblown that even nervous people who think astronomy is little more than black magic's gateway drug will hear about it.   Hotels along the totality path are already taking reservations for late August.   Naturally, we want to jump into the fray.

 

This article will merely provide the most basic total solar eclipse information.   We will post more articles as we draw nearer to the event, itself.    We promise that they'll be few and far between in 2016.  Also, please refer to the 2017 Solar Eclipse web-page http://usm.maine.edu/planet/august-21-2017-total-solar-eclipse.   Mind you, we're constructing this page slowly, so it appears rather threadbare at the moment. 

 

Sadly, we must ruin the mood by disclosing that the eclipse will not be total in New England.   We high northern sky watchers will only observe a partial eclipse.     In Portland, for instance, the Sun will be 58.8% obscured by the moon at maximum eclipse.   One must take heart, however, as New Englanders will experience a total solar eclipse on April 8, 2024, slated also to be the date of the century's most menacing blizzard.  

 

This image shows the solar eclipse's totality path. Only observers along this path will be able to observe a total solar eclipse.  Observers to the north and south of this path will see a partial solar eclipse, the magnitude of which decreases with increasing distance from it.   In Portland, Maine, the Sun will be 58.8% obscured at maximum eclipse.   In Miami, Florida, the Sun will be 78.3% obscured.   (Nashville, TN, is the only large American city within the totality path.) 

 

The eclipse circumstances, i.e. its duration and magnitude, vary considerably with location.   Observers within the totality path will behold a total solar eclipse.    Observers outside this path, but within the region bordered by the northern and southern eclipse limits, will observe a partial solar eclipse.    The eclipse magnitude, defined as the percentage of the Sun's diameter blocked by the moon,* deceases within increasing distance from the totality path. The closer one is to the totality band, the greater the eclipse will be,

Although the eclipse will only be partial, we will still be able to observe celestial mechanics in motion as the moon glides across the Sun.        That, in and of itself, justifies the hype that will most assuredly precede this magnificent event. 

More to come....in future.

 

 

 

 

 

*We have to differentiate between two values:  "magnitude," and "obscuration," which, though related, are not equal.   Magnitude measures the percentage of the Sun's diameter blocked during the maximum eclipse.   However, obscuration measures the percentage of the entire Sun bloacked at maximum eclipse.   Using Portland as an example, again, the obscuration is 58.8%, but the magnitude of 0.667, meaning that the moon blocks 66.7% of the Sun's diameter, but 58.8% of the entire Sun.