THE SOUTHWORTH PLANETARIUM

70 Falmouth Street      Portland, Maine 04103

(207) 780-4249      usm.maine.edu/planet

43.6667° N    70.2667° W  Altitude:  10 feet below sea level Founded January 1970

2021-2022: XCIII

"Stonehenge might lose a bit of its allure if archaeologists ever unearth croquet mallets."

-Anonymous

THE DAILY ASTRONOMER

Tuesday, March 15, 2022

In Exactly Two Months...

we'll experience a total lunar eclipse, provided, of course, the weather cooperates. And, honestly, this is New England, when has it not? A while ago we devoted a couple articles about this impending eclipse and now that we're merely two months shy of this spectacular event, we wanted to send a reminder that on May 15th/16th, the full moon will glide through Earth's inner shadow like an oil-coated seal down the Kilimanjaro Water Slide in Brazil, sans the splash and screams, naturally. Also, we wanted the most recent subscribers to be made aware of this eclipse and information pertaining to it.

We re-post the time-line:

May 15 - 9:32 p.m. PENUMBRAL ECLIPSE BEGINS

Earth's shadow is divided into two regions: the light, outer part of Earth's shadow, called the 'penumbra,' and the inner region called the 'umbra.' The penumbral eclipse begins when Earth first touches the penumbra. The moon passes completely into the penumbra before it reaches the umbra. Honestly, unless you're one of those mystical poetic types who can actually tell the difference between a whisper of a breeze and a caressing zephyr, you won't notice much during the penumbral part of a lunar eclipse. Perhaps the brilliant moon's pallor is rendered a few phantoms less vibrant, but even that is a stretch.  

May 15    -    10:27 p.m. PARTIAL ECLIPSE BEGINS

This is when the 'action' starts. The umbra is the dark interior shadow. Once the umbral eclipse begins, we'll see Earth's curved shadow against the moon. We'll watch the shadow migrate across the moon until the moon is completely immersed in Earth's shadow.

May 15    -    11:29 p.m. TOTALITY BEGINS

Totality begins when the moon is completed inside Earth's umbra. The moon will not be wholly lost from sight. Instead it will appear reddish, because Earth's atmosphere scatters blue light, but directs red light into its shadow. (We see a blue sky during the sky because of this effect.) The eclipsed moon will reflect this reddish light back to us, producing the ominously named 'blood' moon. One effect that we think is absolutely magnificent is the 'spherical moon' phenomenon. During totality, the color differential across the moon's facade lends it a spherical appearance. The moon actually appears as a crimson sphere in space, as opposed to the full moon's usual disc-like appearance.

May 16    -    12:11 a.m.   MAXIMUM ECLIPSE

When the distance separating the center of the shadow and the moon's center is at a minimum.   

May 16   -   12:53 a.m.       TOTALITY ENDS

At this moment, the moon starts its exit from the umbra.  We will see a thin sliver of the moon emerging from the inner shadow.  

May 16  -    1:55 a.m.    UMBRAL ECLIPSE ENDS

For all intents and purposes, the show is now over.  The moon completely leaves the umbra and appears, well, like a full moon again, except that it remains immersed in the penumbra.

May 16 -    2:50 a.m.    PENUMBRAL ECLIPSE ENDS

The eclipse event is now technically over.  Of course, the moon's brightness is hardly diminished during this last hour because the penumbra is so faint.

Weather permitting, the Southworth Planetarium will be open for the eclipse. We'll offer a brief presentation around 10:00 p.m. in our star dome theatre before venturing outside to observe the event. Our intention is to remain until 1:00 a.m. Experience teaches us that interest wanes -i.e. plummets- once the moon begins to leave the umbra. We never charge admission for the observation of celestial events. Being congenial sorts, we always accept donations, but we won't solicit them that evening.

We do recommend making reservations, however. To do so, please send a reply or call 207-780-4249.

To subscribe or unsubscribe from the Daily Astronomer:

https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1