Sky and Telescope - November 2016 - 53

William Sheehan

Long-time visitor and now Flagstaﬀ resident Bill Sheehan enjoys pondering history on Mars Hill.

SKY & TELESCOPE (2)

Your Turn to Try

To see Amalthea visually, you'll need
plenty of aperture. Also helpful will
be an occulting bar - a thin, opaque
strip placed at the telescope's focus,
used to block the blazingly bright disk
of Jupiter (simulated at left).

day of study, Lowell did not arrive in the dome of the
24-inch Clark until sometime after Slipher - and must
have been disappointed to learn that he'd just missed an
elongation of Amalthea. On the other hand, he had no
reason to think that there wouldn't be many more such
opportunities.
Just before 9 p.m., Lowell recorded another interesting event: Io's reappearance from its eclipse by Jupiter's
shadow. He recorded the following notes:
Nov. 11, 1916
P.L.
8h

52m
54
56
56

10
10
10
50

Amalthea has always been the domain of large apertures, and it's far more diﬃcult to see than challenges
such as Mars' Phobos and Deimos or Sirius's "pup."
The smallest instrument used for a successful visual
observation of which I am aware might have been the
18½-inch refractor at the Dearborn Observatory in
Evanston, Illinois - the same telescope used to discover
Sirius B - by George Washington Hough in 1892. Perhaps readers of Sky & Telescope can beat Hough's record.
Although a tough visual challenge, Amalthea is well
within reach of skilled CCD imagers. For instance,
professional astronomers recorded eclipses of Amalthea
during the marvelous series of mutual events among the
Galilean satellites from September 2014 to June 2015.
So did at least one amateur, Bernd Gährken of Germany, who captured Amalthea's April 7, 2015, eclipse by
Callisto with the 80-cm telescope at the Bavarian Public
Observatory in Munich. Instead of masking Jupiter as
usual, he instead subdued Jupiter with a special ﬁ lter
for the methane's strong near-infrared absorption at 890
nm. Then he used an infrared-sensitive CCD detector to
bring out reddish Amalthea.
The next series of mutual satellite events won't begin
until 2020. But Amalthea still will be there, and amateurs tired of only seeing the Galilean satellites will no
doubt enjoy trying to meet the challenge of glimpsing
or recording this intriguing little moon - the last one
discovered visually and the object of Percival Lowell's
ﬁnal quest. ✦

Eclipse - Reappearance
½
Last Contact
Certainly now

The Moon * November 2016
13

Phases
FIRST QUARTER

November 7, 19:51 UT
FULL MOON

November 14, 13:52 UT
NASA / LRO

The following morning he suﬀered an intracerebral
hemorrhage and passed away in his bedroom at 10 p.m.
that evening, without ever regaining consciousness. His
wife, Constance, who made sure to keep the bedroom
exactly as it was when he died, recorded in chalk on the
wall, "Percival Lowell's earthly existence terminated in
this chamber upon the green couch."
Slipher carefully rescued the last pages of Lowell's
observing notes and put them in a cigar box, after which
they were long forgotten. They were rediscovered 97
years later, when Lowell Observatory preservationist
Michael Kitt was sorting through piles of material abandoned in the 100-year-old Administration Building (now
the historic Slipher Building).
These evocative notes are now housed, along with
other precious documents, in the Lowell Observatory's
new Putnam Collection Center.

LAST QUARTER

November 21, 8:33 UT
NEW MOON

November 29, 12:18 UT

Nov. 3
For key dates, yellow dots indicate which part
of the Moon's limb is tipped the most toward
Earth by libration under favorable illumination.

Distances

Favorable Librations

Perigee
356,509 km

November 14, 11h UT
diameter: 33′ 31″

Apogee
406,554 km

November 27, 20h UT
diameter: 29′ 23″

Helmholtz (crater) November 3
Pythagoras (crater) November 13
Byrd (crater)

November 15

Sk yandTelescope.com November 2016

http://www.SkyandTelescope.com

Sky and Telescope - November 2016

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