My first Magazine Sky & Telescope - 01.2019 | Page 20

JANUARY’S LUNAR BLACKOUT
by Joe Rao
The Great
American Lunar
A “disappearing” full Moon in the fi rst weeks of 2019 is
wonderfully timed and placed for skywatchers in the Americas.
O
n the night of January 20–21, for the third time
in less than a year, the Moon will become com-
pletely immersed in Earth’s shadow and create one
of nature’s most beautiful spectacles: a total lunar eclipse.
Last January 31st, the timing of totality favored the lands
around the rim of the Pacifi c Ocean; those in the western
U.S. could catch it before moonset. Then, on July 27th, the
longest total lunar eclipse until the year 2123 took place
over the Eastern Hemisphere, with no part of that celestial
event visible from North America.
But soon those in the Western Hemisphere will have
ringside seats for the fi rst total lunar eclipse visible in its
entirety since 2015. And this will be an exceptional eclipse
in more ways than one.
First, it will take place on the Sunday night of a 3-day hol-
iday weekend in the U.S., ensuring that kids of all ages will
be able to stay up and watch this sky show no matter how
late. As astronomer Fred Espenak points out, “Seeing such an
event can spark the imagination and interest of a child — and
isn’t that where future scientists come from?”
Second, because this eclipse occurs during northern
mid-winter, it occurs eerily high in the sky for northerners.
At mid-totality, the Moon will stand 83° above the horizon
18
JA N UA RY 2 019 • SK Y & TELESCOPE
p UMBRA REVEALED In Beijing, China, Letian Wang imaged the lunar
eclipse of December 10, 2011. His composite of i ve exposures shows a
broad expanse of the southern edge of Earth’s umbral shadow.
from Miami and 70° from New York. Farther west, the mid-
point occurs 69° high in Houston, 66° in Chicago, 58° in
Denver, and 49° in Los Angeles.
Third, as the timetable on the following pages demon-
strates, totality commences before midnight across all of the
contiguous United States. Eclipse watchers in the Hawaiian
Islands will see the Moon climb out of the Pacifi c Ocean at
sunset on the 20th, with roughly half of it already immersed
in shadow. Meanwhile, it’s a predawn event on the 21st as
seen from western Europe and Africa.
Some Eclipse Projects
A lunar eclipse provides interesting viewing for both young
and old, from astronomy neophytes to assiduous amateur
astronomers. Here are a few suggestions for January’s event
that require only simple equipment — or none at all.
The penumbra: As shown in the diagram on page 20,
Earth’s shadow cone has two parts: a penumbra, the shadow’s
pale fringe; and an umbra, the darker central region.