WHEN TO
VIEW THE
PLANETS
EVENING SK Y
Mercury (west)
Venus (southwest)
Uranus (south)
Neptune (southwest)MIDNIGHT
Uranus (west)
MORNING SK Y
Mars (southeast)
Jupiter (southeast)
Saturn (southeast)42 ASTRONOMY • JANUARY 2020
EAQUARIUSVenusNeptuneqr9683N0.5°A conjunction for the ages (^)
The evening of January 27 finds Venus passing within a few arcminutes of
distant Neptune in their closest approach since 1984.
COMET SEARCH I A performance fit for a queen
WHAT SEEMS TO BE SHAPING
UP as the Northern Hemisphere’s
brightest comet of 2020 gets the
year off to a nice start. Comet
PanSTARRS (C/2017 T2) should
reach 9th magnitude this month
as it crosses the star fields along
the border between Cassiopeia
the Queen and Perseus the Hero.
An 8-inch telescope should
pick up the comet’s compact
glow from the suburbs. Crank the
power to 150x or more and you’ll
see an out-of-round shape and
well-defined southern flank.
The observing window opens
January 13, when the Moon rises
about two hours after darkness
falls. PanSTARRS then lies 1° north
of the 4th-magnitude star Eta (η)
Persei. Imagers shooting through
a 70mm lens have two weeks to capture the comet’s glow crossing a wonderful Milky Way backdrop
some 4° south of the Heart and Soul nebulae (IC 1805 and IC 1848, respectively).
Better yet, PanSTARRS passes less than 1° north of the Double Cluster on January 26 and 27. The
comet moves slowly enough that the view should still be great a couple of nights before and after.
This visitor from the distant Oort Cloud passes through a beautiful section
of the Milky Way on the border between Cassiopeia and Perseus.
31
Jan 1
6
11
16
21
26
CASSIOPEIA
PERSEUS
d
IC 1848 IC 1805
Double
Cluster
Path of
Comet
PanSTARRS
N
E
1°
Comet PanSTARRS (C/2017 T2)
opportunity to see it comes
on the 25th. If you have a clear
sky and an unobstructed hori-
zon toward the west-southwest,
search for a wafer-thin crescent
Moon hanging 3° high 30 min-
utes after the Sun sets. Once
you find it, hunt for magnitude
–1.1 Mercury 2° to its right.
You’ll have only about 10 min-
utes to catch them before they
sink out of sight.
Your chances of spotting
Mercury improve as the month
winds down because it gains
nearly 1° of altitude with each
passing day if you observe at
the same time relative to sun-
set. On the 31st, the planet
stands 6° high a half-hour after
sundown. Its altitude will
nearly double by the time it
reaches greatest elongation
during February’s second week.
Uranus lies high in the
southern sky during the early
evening hours and makes a
fine target through binoculars
or a telescope. It lies among the
background stars of Aries, 12°
due south of the Ram’s bright-
est star, 2nd-magnitude Hamal
(Alpha [α] Arietis). The mag-
nitude 5.8 planet glows
brightly enough to see easily
through binoculars if you
know where to look. But that’s
the challenge — few guide stars
lie nearby to help your search.
Start by finding Hamal and
magnitude 3.8 Alpha Piscium,
which resides in southeastern
Pisces. This unassuming star
lies 21° south of Hamal and
appears 20 percent as bright.
Use binoculars to scan between
these stars and get used to how
many fields of view separate
them. Then estimate their mid-
point and drop 1° south of this
spot to find Uranus.
A few other stars lurk in
Uranus’ vicinity. Four of these
6th- and 7th-magnitude suns
form a slightly crooked line
that extends 4° north-south.
The planet, which glows a little
brighter than these field stars,
lies just west of the line during
January’s first three weeks.
Uranus’ eastward motion
against this backdrop makes
it a fifth member of the line
by month’s close.
If you can’t identify the
planet through binoculars, aim
a telescope at your suspected
quarry. Only Uranus shows a
disk, which spans 3.6" and glows
blue-green. The distinct color
arises because methane in the
ice giant’s atmosphere absorbs
red sunlight while ref lecting
blue. Your best views of Uranus
will come when it rides high in
the south in early evening.
Once Uranus sets — near
2 a.m. local time in early
SKY THIS MONTH — Continued from page 37