Sky & Telescope - April 2022 - 46

APRIL 2022 OBSERVING
Sun, Moon & Planets by Gary Seronik
To find out what's
visible in the sky from
your location, go to
skyandtelescope.org.
Mercury Makes Good
A fine showing for the innermost planet is just one highlight in a busy month.
MONDAY, APRIL 4
The Moon visits the Pleiades cluster
in Taurus roughly once a month. But
the very best meet-ups are the ones
that feature a thin lunar crescent in a
reasonably dark sky, which happens in
the early evening in spring and the early
morning in summer. The reason a thin
crescent is best is simple: The collection
of stars that make up the Pleiades' minidipper
shape mostly shine around 4th
magnitude, which is faint enough to
be overwhelmed when the lunar disk is
more than 50% illuminated, at least so
far as the naked-eye view is concerned.
That's why this evening's event is so
appealing - the Moon is less than four
days old and just 14% lit as it sits just
4° below left of the cluster. The pair will
make for a fine, early-evening naked-eye
sight, but if you use binoculars the view
really gains luster. Not only will you
catch more Pleiads, but you'll also get to
enjoy seeing earthshine gently illuminating
the " dark " portion of the Moon.
TUESDAY, APRIL 5
The morning sky is the place to be in
April as four naked-eye planets subtly
shift positions on a daily basis. The first
highlight of the month's series of dawn
delights is a close pairing of Mars and
Saturn on the 5th. Mars's eastward
motion has been bringing it nearer and
nearer to Saturn, and on this date it
sits a mere 24′ below the ringed wonder.
That's slightly less than one Moon
These scenes are drawn for near the middle
of North America (latitude 40° north, longitude
90° west). European observers should move
each Moon symbol a quarter of the way toward
the one for the previous date; in the Far East,
move the Moon halfway.
46
APRIL 2022 * SKY & TELESCOPE
diameter, which means the two can
be seen together in a small telescope
used at moderate magnification. Such
a view will show Saturn's magnificent
rings and render Mars a tiny, ruddy
disk. Interestingly, both planets are very
nearly the same brightness, with Saturn
shining at magnitude +0.9 and Mars
at +1.0. But you certainly don't need a
telescope (or even binoculars) to enjoy
this pairing - an alarm clock is likely
the only piece of gear required since the
best time to look is around 5:30 a.m.
(local daylight time), before twilight
brightens the sky too much.
MONDAY, APRIL 18
There's something irresistibly eyecatching
about a set of evenly spaced
bright planets strung out in a line. And
that's exactly what we have at dawn
today. Starting from the horizon and
Moon
Apr 6
TAURUS
CAPRICORNUS
Aldebaran
Moon
Apr 5
Pleiades
Saturn
Mars
10°
Moon
Apr 4
Venus
April 3 - 6
9 pm
proceeding up and to the right, you
get Jupiter (magnitude -2.1), Venus
(-4.2), Mars (+1.0), and Saturn (+0.9).
Obviously, this delightful configuration
didn't spring up overnight - the quartet
has been in some sort of " line " since
Jupiter emerged from solar conjunction
at the start of the month - but the gaps
between the planetary dots are most
equal on this morning.
The line is nearly 32° long, which
means if the planets were perfectly
spaced each would be separated from
its neighbor by a little less than 11°. So,
are they? Plus or minus ½°, yes! The
exception is Mars and Saturn, which
have only 9° between them. But given
that they're the faintest of the foursome,
their deviation from perfection seems
a little less obvious. This is one of those
sky sights that is purely for naked-eye
enthusiasts - even binoculars will
Dawn, April 5
45 minutes before sunrise
Looking West,
halfway up
Moon
Apr 3
Looking Southeast
http://www.skyandtelescope.org
Sky & Telescope - April 2022

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