Sky & Telescope - April 2023 QR - 35

FRED ESPENAK (2)
CHILEAN ECLIPSE CROWN The solar corona is only visible for a
few, brief minutes during a total eclipse of the Sun. Because the corona
encompasses an enormous range of brightness (the innermost corona
is over 1,000 times brighter than the outer corona), it is difficult to photograph
what the eye can see. This composite of 72 separate exposures
has been processed to reveal and emphasize the fine structure present in
the solar corona during the total solar eclipse of July 2, 2019.
It's a very restricted impact but dramatic: April cloudiness
drops from 80% to 65% as the central line crosses the shore.
Prince Edward Island's North Cape protrudes into the eclipse
shadow almost to the central line, giving the town of Tignish
(3m 11s totality) the distinction of being the most promising
observing spot between Vermont and the end of the eclipse
path in the North Atlantic.
Alas, sunny weather is very hard to come by, and winter is
very much still in evidence in Newfoundland. Measurements
from weather stations show that a hopeful 30% to 35% of
April daylight hours are sunny, but weather satellites indicate
that skies are cloudy more than 80% of the month. Climate
statistics show average snowfalls of 15 to 40 cm (6 to 16 in)
in April, with precipitation occurring on half of the days. To
extract the most that the area's climate can offer, determined
eclipse seekers should travel to Cape Bonavista, the last bit of
land under the shadow, where totality endures for 2m 54s.
Leaving Canada at a velocity of 2.08 km/s, the umbra
races 2,450 km across the North Atlantic before slipping off
our planet and returning to space.
An Eclipse for Everyone
Over the eclipse's total duration of 3 hours 15 minutes, the
umbra travels along a 14,800-km strip that covers an area
representing just 0.52% of Earth's surface. Even a year out,
excitement is building for the 2024 eclipse. This is due in
2017 ECLIPSE FROM CASPER, WYOMING This photo is a combination
of images shot with two separate cameras. The first camera
captured the partial phases through a solar filter at 5-minute intervals. A
second camera had no solar filter and was used to photograph the landscape,
trees, and totally eclipsed Sun. The images were later processed
and stacked to produce the final composite.
DIAMOND RING In the final seconds before totality, the shrinking
crescent Sun produces a short, brilliant segment along one edge of the
Moon known as the diamond ring. As the solar corona emerges into
view in the rapidly darkening sky, the diamond grows smaller and breaks
up into a string of bright points called Baily's Beads, which vanish as
totality begins.
large part to the 2017 event, which introduced millions of
people to the grandeur of totality.
It's a signature of the various climatologies crossed by
this eclipse that watchers from Texas to Ohio may have to
contend with severe-weather-producing thunderstorms,
while those from Ohio to Newfoundland may encounter
snowstorms and even late-season blizzards. With such a
variety of possible weather constraints, you should turn to
the forecasts for help with any last-minute decisions. You'll
find that information is readily available on the internet,
and that predictions reliable enough for serious decisionmaking
can be had a week in advance.
Weather permitting, everyone in North America (except
most of Alaska) will see something grand on eclipse
day - even those outside the zone of totality. Looking
up from Los Angeles at mid-eclipse - using safe viewing
techniques, of course - you'll see 58% of the solar disk's
diameter covered by the Moon. From New York City, it will
be 91%. The partially eclipsed Sun will be worth viewing
even from such widely separated locations as Honolulu,
Hawai'i (28%); Vancouver, British Columbia (28%); and
Miami, Florida (56%).
A total solar eclipse is not only a grand visual spectacle,
but it's also a chance to convince family, friends, and neighbors
that astronomy isn't just for astronomers. And maybe,
just maybe, the 2024 eclipse might inspire some child to
become the next Galileo, Newton, or Einstein!
¢ Astronomer FRED ESPENAK manages the websites eclipsewise.com
and MrEclipse.com. Meteorologist JAY ANDERSON
has researched eclipse weather forecasts since 1979 and
dispenses meteorological information at eclipsophile.com.
sk yand tele scope .o r g * APRIL 2023 35
http://www.eclipsewise.com http://www.eclipsewise.com http://www.MrEclipse.com http://www.eclipsophile.com https://skyandtelescope.org/
Sky & Telescope - April 2023 QR

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