Sky & Telescope - March 2025 - 49

NASA EARTH OBSERVATORY IMAGES BY JOSHUA STEVENS, USING LANDSAT DATA FROM THE U.S. GEOLOGICAL
SURVEY AND MATTHEW MONTANARO / GSFC / RIT
the penumbra was much more obvious
on my camera's live-view screen
compared to what my eyes saw. I recommend
this approach as a good way to
monitor the Moon's progress during the
event's early phases.
The umbra takes its first nibble of the
Moon at 5:09 UT - the start of partial
eclipse. Well before totality, attentive
observers will notice the shadowed
portion of the lunar disk glowing
smoky-red from sunlight refracted by
Earth's atmosphere. Excitement mounts
as totality approaches. When the last
sunlit sliver of Moon is swallowed by
the umbra at 6:26 UT, you can almost
imagine a chorus of " wows! " rising
skyward from eclipse watchers.
During the eclipse, the Moon is
relatively far from Earth and just a
few days shy of apogee, which occurs
on March 17th. As a result, the smallish
lunar disk spends a generous 66
minutes crossing the northern portion
of the umbra. Absent direct sunlight,
the eclipsed orb always looks small and
subdued to my eye compared to the
boisterous brilliance of the full Moon.
The eerie darkness that descends over
the landscape during totality further
adds to the contemplative mood of this
leisurely paced show.
Dedicated observers use the five-point
Danjon scale (in which 0 is darkest,
4 is lightest) to estimate the brightness
and color of the eclipsed Moon -
qualities linked to the clarity of Earth's
atmosphere. Major volcanic eruptions
can pollute the air with aerosols that
strongly darken the Moon (see page 58).
Photographing a lunar eclipse is
straightforward. Indeed, with the capabilities
of modern DSLR and mirrorless
cameras, you hardly need a tripod for
the partial phases. But a sturdy support
is essential when the Moon dwindles to
a crescent and especially during totality
when exposures are longer. A tracking
mount ensures good photos during
all phases, particularly with longer
lenses. While a smartphone works for
handheld shots, most devices render
the lunar disk disappointingly small.
Instead, set up a telescope and either
hold your phone's lens up to the eyepiece,
or purchase an adapter
to attach it directly. This afocal
method yields screen-filling
images you'll be eager to share
on social media.
You can also use a telescope
on a tracking mount to shoot
a close-up video of the eclipse
to see if you can capture
flashes from meteoroids striking
the lunar surface. If you
own a smart telescope, put it
to work creating a time-lapse
or video while you sit back and
watch the event unfold with
binoculars or a second scope.
Sky & Telescope Senior
Contributing Editor Roger
Sinnott encourages observers to record
the times when specific craters enter
and exit the umbral shadow. The umbra
is larger than pure geometry predicts
because of atmospheric effects, which
vary from eclipse to eclipse. For instructions,
check out Roger's article at
https://is.gd/lunartiming.
On eclipse night, you'll want to
bundle up warmly. Even in early spring,
temperatures in some regions may drop
below freezing late at night. But imagine
what it's like on the Moon's surface as
Earth blocks the light and heat from the
Sun. During the May 2022 total lunar
Minima of Algol
Feb.
UT
2
5
8
11
14
17
20
22
25
28
20:55
17:45
14:34
11:24
8:13
5:02
1:52
22:41
19:30
16:20
Mar.
3
6
9
12
15
17
20
23
26
29
tLandsat recorded this infrared image
sequence during the total lunar
eclipse of May 16, 2022, revealing
how different regions of the Moon
retain heat as sunlight is extinguished
during the event. Impact
craters retain higher temperatures
(brighter appearance) compared to
the loosely textured lunar regolith.
The warmest and most prominent
crater is Tycho, glowing brightly in
the lunar south.
eclipse, the Thermal Infrared
Sensor instruments on the
Landsat 8 and 9 satellites
recorded rapidly plummeting
temperatures on the Moon as
it slid into Earth's shadow. The
temperature dropped from a
toasty 97°C (207°F) down to −93°C.
The data also revealed that different
features cooled at different rates. Craters
tended to hold onto their heat longer
than their surroundings.
After mid-eclipse at 6:59 UT, the
Moon slowly drifts out of the umbra
and back into sunlight starting at 7:32
UT. The event concludes when the
Moon exits Earth's penumbral shadow
at 10:02 UT. From beginning to end,
the eclipse lasts 366 minutes. The next
one occurs on September 7th when the
Moon puts on a similar show but for
the opposite side of the planet.
UT
29
13:09
9:58
6:48
3:37
0:26
21:16
18:05
14:54
11:44
8:33
These geocentric predictions are from the recent
heliocentric elements Min. = JD 2457360.307
+ 2.867351E, where E is any integer. They were
derived by Roger W. Sinnott from 15 photoelectric
series in the AAVSO database acquired
during 2015-2020 by Wolfgang Vollmann, Gerard
Samolyk, and Ivan Sergey. For a comparison-star
chart and more info, see skyandtelescope.org/algol.
18
30
PERSEUS
38
Algol
21
TRIANGULUM
34
pPerseus is conveniently high in the northwest
during evening hours in March. Every
2.87 days, Algol (Beta Persei) dips from its
usual magnitude 2.1 to 3.4 and back. Use this
chart to estimate its brightness in respect to
comparison stars of magnitude 2.1 (Gamma
Andromedae) and 3.4 (Alpha Trianguli).
sk yand tele scope .o r g * MARCH 2025 49

https://www.is.gd/lunartiming http://www.skyandtelescope.org/algol http://skyandtelescope.org

Sky & Telescope - March 2025

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