THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
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70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian date: 2458778.16
2019-2020: XXXVI
"There are two ways to live: you can live as if nothing is a
miracle; you can live as if everything is a miracle." -Albert Einstein
THE DAILY ASTRONOMER
Tuesday, October 22, 2019
Preparing for the Transit
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*THE SOUTHWORTH PLANETARIUM WILL BE OPENFOR THE TRANSIT OF MERCURY *
Monday, November 11, 2019
Watch this event with us!
Free and open to the public.
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[image: 771753373_1280x720.jpg]
Slightly less than 20 days!
On November 11, 2019, we -weather permitting, schedules allowing- will
observe the direct passage of Mercury across the Sun. These events,
called "transits," are exceedingly uncommon. (Mercury transits the Sun only
14 times in the 21st century. Venus won't transit the Sun again until
December 2117.) While they don't offer the spectacle of solar eclipses or
the pop and pizazz of meteor storms, transits remain one of the most
intriguing of all celestial events. By watching the passage of a planet
across the Sun, not only are we seeing direct evidence of the heliocentric
(Sun-centered) solar system model, we are benefitting from the power of
mathematical astronomy: its ability to precisely predict cosmic events
years, centuries, even millennia in the future.
In short (too late), we'll be watching an entire world traversing our
parent star. Although Mercury and Venus have literally crossed the Sun
from Earth's perspective millions of times throughout the vast expanse of
natural history, we have only known about -and been able to observe- these
transits since the early 17th century.*
Let's review the facts:
The transit of Mercury will begin in Portland at 7:36 a.m. Mid transit occurs
at 10:20 a.m. and the transit ends at 1:04 p.m. for a transit duration of 5
hours and 28 minutes. The times will vary only slightly in other New
England and eastern American locations. Do note that the transit beginning
time refers to first contact. Mercury first appears to touch the Sun's
edge at 7:36 a.m. The entire planet will be visible against the Sun about
1 - 2 minutes later.
As Mercury is so small and will be 63 million miles from Earth on November
11th, this transit is only observable through a telescope or binoculars.
One MUST either use a protective filter covering the end of the optical
tube** or must project the Sun onto an opposing surface to allow for safe
viewing.
Mercury will appear as a small black dot moving along a path that nearly
brings it across the Sun's center. This particularly long trajectory
will keep Mercury in sight almost five and a half hours. We'll have
plenty to time to observe this transit. One should certainly at least
spend a moment watching this transit, as we here in the eastern United
States will not be able to see another Mercurian transit until May 7, 2049!
(Mercury will transit the Sun twice in the intervening period: in 2032
and 2039. However, neither transit will be visible here.)
On November 11th, the first world will transit the Sun, giving us a rare
opportunity to see it during the day. Mercury will then return to the
early morning eastern sky in late November, to begin yet another series of
oscillations that will swing it from the morning to the evening and back to
the morning sky again. Being so close to the Sun, Mercury is the most
elusive of all the visible planets. On November 11th, it will literally be
front and center in our view. We hope that you can view it with us
*Pierre Gassendi was the first person to observe a transit. He watched a
transit of Mercury in 1631.
**Do you have a "protective" eyepiece filter. Do your eyes a favor and
toss it into the ocean. Let Davy Jones obliterate his eyes as he tries to
observe the Sun through it. The problem with eyepiece filters is its
location: at the very focal point of the solar energy. One does NOT want
to look through such an eyepiece should the filter fail.
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