Planetarium

August 21, 2017 Total Solar Eclipse!

Greetings!

 

THE ECLIPSE EVENT IS BOOKED!  IF YOU HAVEN'T YET RESERVED YOUR SPACE, PLEASE SEEK ANOTHER VENUE.

OUR SINCEREST APOLOGIES!

Welcome to a work in progress!  We're setting aside a cell in our web site catacombs specifically for a special event: the August 21, 2017 total solar eclipse. During the next few months, we will be constantly adding new material to this site.   Soon, we intend to have a comprehensive page replete with time tables, charts, diagrams, glossaries, explanations. questions/answers and much more!

Please send any solar eclipse or related questions to  edward.gleason@maine.edu

Before we proceed, we have to tell you we won't see the TOTAL solar eclipse here in New England.   Instead, we'll experience a partial solar eclipse.    (As a consolation, Maine will experience a total solar eclipse on April 8, 2024.)

total solar eclipse

A map showing the total solar eclipse's "totality path," the region where observers will be able to see a total solar eclipse.   Alas, Southern Maine sky watchers will not be able to see a total solar eclipse on August 21.  Instead, we'll see a "partial solar eclipse," meaning that the moon will only partially cover the Sun from our perspective.  For instance, in Portland, the sun will be 58.8% obscured at maximum eclipse.

total solar eclipsepartial solar eclipse

On the left, an image of a total solar eclipse.  Here, the moon covers the Sun and exposes the outer corona.  On the right, an image of a partial solar eclipse.  In this instance, the moon will only partially cover the Sun.

 

 

August 21, 2017!Arguably, one of the most famous astronomical dates of the decade, if not the century. (Granted it is a bit early for those sort of predictions.)   The Great American Eclipse will dazzle and delight us all on August 21, 2017.  Or, more correctly, will dazzle and delight those observers located within the totality path.  Those of us outside this path will still observe a partial eclipse, but, as any eclipse lover would attest, a partial eclipse cannot compare to the real thing:  the direct passage of the moon in front of the Sun.    Due to the pre-event hype, this eclipse will likely be the most watched eclipse in human history.    If you haven't yet booked a room along the totality path, good luck finding one now!  Even all the rooftop segments are taken.      Fortunately, we can still join in on the hype and eagerly anticipate next month's eclipse.*    In this two part series, we'll go over the basic details pertaining to the eclipse.     As usual, we'll opt for the Q/A format and will add some talking points, as well. WHERE IS THE TOTALITY PATH?
In the graphic below we can see the totality path extending from the northwestern Pacific to the southeastern Atlantic coast.   This is the first time since 1918 that a total eclipse totality path has connected both of our country's coasts.   Any observer within this path will see a total solar eclipse, weather permitting.    Observers north or south of the path will see a partial solar eclipse.  The eclipse magnitude, defined as the percentage of the Sun's diameter covered by the moon- deceases with increasing distance from this path.   WHAT IS THE ECLIPSE MAGNITUDE IN SOUTHERN MAINE?In Portland, the eclipse magnitude is about 0.67, meaning that the moon will block 67% of the Sun's diameter.  However, the obscuration will only be about 58.8% at maximum.     Even though the moon will block about 2/3 of the Sun's diameter, it will cover less than 60% of the Sun's face!   
WILL IT EVER BE SAFE FOR US TO SEE THE SUN DURING THE ECLIPSE?

The ONLY time it is ever save to look at a solar eclipse is during totality, when the moon completely blocks the Sun.  It is NEVER safe to look at a partially eclipsed Sun!   Sorry for raising our voices, but we don't want you to injure your eyes during this eclipse event.   


WHAT TIME DOES THE ECLIPSE OCCUR?
The times vary with location.  I have listed the times corresponding to Portland, Maine PORTLAND, MAINE TIMETABLE Eclipse begins:                  1:29:20 p.m. Maximum eclipse:            2:45:53 p.m.   (58.8% obscuration) Eclipse ends:                     3:57:02 p.m. The farther north you observe, the smaller the obscuration percentage.  We include some talking points.Tomorrow, much more on the Great American Eclipse! TALKING POINTS --This is the first total solar eclipse to have its totality path only on American soil since 1257!   (Granted, the USA hadn't yet been conceived of in the 13th century. We are referring to the land areas currently designated as America.)     The next total solar eclipse that will be limited to American soil occurs in 2316! --The last time we experienced a total solar eclipse with a totality path extending between the Pacific and Atlantic coasts was June 1918.    (That eclipse path extended between Washington state and Florida.) 
 WHY DON'T SOLAR ECLIPSES OCCUR EVERY MONTH?A solar eclipse occurs when the moon moves in front of the Sun. The moon must be new (between the Sun and Earth) for such an eclipse to occur.     The moon must also be directly between the Sun and Earth when new.  Most often, the new moon will be north or south of the Earth-Sun plane, called "the ecliptic," because the moon's orbit is inclined about five degrees relative to the ecliptic.   If the moon's orbit were precisely aligned with the ecliptic,eclipses would occur at every new moon.     Granted, even if this were to occur, the eclipse would still only be visible along a narrow totality path which would be at different locations at each eclipse.    IS THERE AN ASSOCIATED LUNAR ECLIPSE?Yes, every solar eclipse is associated with a corresponding lunar eclipse.   As this solar eclipse is expected to be the most watched eclipse in human history, the associated lunar eclipse has been largely ignored.   Also, that lunareclipse will only be partial.  Only part of the full moon will move into Earth's umbra (inner shadow) on the night of August 7/8.   It will be entirely visible parts of Asia and Australia.    None of it will be visible in the USA.  Of course, as our country will get a solar eclipse entirely to itself, one can hardly complain about not also seeing a partial lunar eclipse.   WHEN WILL TOTAL SOLAR ECLIPSES END?First, some background.   The moon is moving away from Earth by about 3 - 4 centimeters a year.    Consequently, the moon's apparent size will decrease with time.      Presently, the moon and Sun's apparent sizes are about half a degree, so the former can at times precisely block the latter.    However, in about 600 million years,* the moon will appear so small that the only solar eclipses will be annular:   a "ring of fire" will remain visible around the moon during totality.     
Annular solar eclipse​

 WHEN WILL MAINE NEXT EXPERIENCE A TOTAL SOLAR ECLIPSE
April 8, 2024.The totality path will slice through western Maine, missing the southern coast.     We can expect thousands of people to gush into western Maine to observe this celestial spectacle.  Knowing our luck, we can also expect a blizzard that day. This is certainly NOT the last word we'll utter about this fantastic event.   Much more to come...some of it on even on time...  *Mathematical astronomers have not reached a consensus on this matter.    The 600 million year figure is derived from the work of Belgian astronomer Jean Meeus.  I am citing that figure because Meeus' work is generally unassailable.