Astronomy - USA (2022-02)

WWW.ASTRONOMY.COM 33

RISING MOON I The mountain above the pole

WHERE’S THE BEST PLACE on the Moon for

a solar power station? That would be a massive

hill on the lunar farside, just beyond the south

pole, which suffers only a brief interruption in

continuous sunlight. M5, unofficially known as

Mount Clementine, undergoes a short eclipse as

the shifting shadow of its neighbor M4 swings

across it once a month. By contrast, most places

on the Moon must endure the day-night cycle

that sports 14 Earth nights of darkness.

Without a doubt, Mount Clementine is the

easiest farside feature to see — when the time

is right. As the Moon hits a high above the

Earth-Sun plane (the ecliptic), depicted as

a red line on our Star Dome (see

page 34), we have the opportunity to

peer a bit beneath its south pole. Start

on the 14th and return nightly through

Full Moon on the 16th, when we get a

near-perfect, outstanding 3D perspective.

It’s as if you were in a helicopter flying low over

waves rushing toward a beach. Our extra view-

ing angle shows us the shadow cast by every

hill, reminiscent of the way dark eyeliner high-

lights the white of the eye.

Instead of shadows lying west of a rising Sun,

here they are cast southward, gradually swing-

ing around in an arc. The modestly tall bump in

front of Mount Clementine at first casts its

shadow to all the way to the base of M4; on fol-

lowing nights it marches eastward, crossing the

base of Clementine. A few nights later, M4 itself

Water-bearer. A telescope will
reveal a 6th-magnitude star 4°
northeast of Phi (φ) Aquarii;
Neptune lies only 1.5' due north
of this star on Feb. 3. The ice
giant tracks to the northeast
during the rest of the month
and is consumed by twilight
before month’s end.
Uranus is up all evening
during February, located in
Aries the Ram. It sets just after
local midnight early in the
month and about two hours
earlier by the end of February.
At magnitude 5.8, it’s just bright
enough to spot with the
unaided eye. But in a sparse
region devoid of bright stars,
it ’s hard to track down.
The planet lies about 11°
south-southeast of Hamal, the
brightest star in Aries, and 5.3°
north-northwest of Mu (μ) Ceti.
On Feb. 1, it pairs up with
6th-magnitude 29 Arietis — the
two are just 25' apart. In bin-
oculars, they should stand out
as a close double, with slightly
bluish Uranus due south of the
star. A waxing Moon lies in the
vicinity on Feb. 7. Uranus con-
tinues its easterly trek, moving
to a point 43' east of 29 Arietis
by Feb. 28. Point your telescope
at Uranus to spy its 3"-wide
disk. This distant giant lies
1.9 billion miles from Earth.
All other planetary action
occurs in the predawn sky, with
four major planets visible in the
latter half of February.

Mount Clementine

puts Clementine in darkness, as in the

image here. Use Casatus, Moretus, and Newton

to nail the identification.

Be patient and wait for good seeing. The

views will be quite rewarding. You may also pick

out the crater rims of Shackleton and Faustini on

the farside! At lower power, the glare from the

Full Moon can be rather unbearable in larger

instruments, so use a dark blue or green filter.

But as you step up the power, you might not

need one. Go back for another round next

month near Full Moon, since the geometry

almost repeats.

— Continued on page 38

METEOR WATCH I Gone, but not forgotten

THERE ARE NO major meteor showers this

month, but it’s still worth venturing out into

the country in search of dark skies. While

sporadic meteors can be seen at any time,

February is also a good time to spot the

zodiacal light.

Our solar system is filled with the dusty

remains of long-dead comets. Sunlight reflect-

ing off these billions of meteoritic particles

causes the zodiacal light. It is detectable by

eye soon after sunset under the right condi-

tions. Select an observing location where the

western sky is very dark, with few towns sport-

ing street lighting. As the sky darkens, an hour

or so after sunset, a cone-shaped glow similar

to the Milky Way will become visible. It will

appear steeply angled from the western hori-

zon and aligned with the ecliptic, extending

upward through Taurus the Bull. Observers

located at higher altitudes are at an advan-

tage, as they avoid the deeper dust-laden

atmosphere of Earth.

Gentle light

This month and next, get a glimpse just

beyond the lunar south pole. CONSOLIDATED

LU NAR ATL A S/UA/LPL. INSET: NASA/GSFC/ASU

Pick a time with a moonless sky to go in search of the

zodiacal light’s elusive glow. NPS PHOTO/JACOB HOLGERSON

M4 M5 (Mount Clementine)

Casatus

Moretus

N

E

VENUS reaches an unusually

bright greatest brilliancy

Feb. 12. To see it at its brightest,

catch it the next morning,

blazing at magnitude –4.9.

OBSERVING

HIGHLIGHT

Newton