Sky & Telescope - April 2021 - 46

APRIL 2021 OBSERVING
Sun, Moon & Planets by Gary Seronik
To find out what's
visible in the sky from
your location, go to
skyandtelescope.org.

Venus Returns
The brilliant Evening Star pops up at dusk after a long absence.
TUESDAY, APRIL 6

WEDNESDAY, APRIL 7

Each month the Moon serves as a helpful tour guide highlighting the brightest
planets strung out along the ecliptic.
And April is no exception. During
the month, Earth's companion pairs
up with a trio of planets, beginning
this morning with Saturn. The ringed
planet is currently a +0.8-magnitude
spark in the zodiacal constellation
Capricornus. Saturn rises at roughly 4
a.m. local daylight-saving time, followed
20 minutes later by the waning lunar
crescent. The Moon is about 4½° below
Saturn as morning twilight begins to
brighten the sky. Telescope users should
be able to get reasonable views of Saturn
as the planet attains an altitude of 20°
half an hour before sunrise in early
April. The planet's famous rings are
presently tilted open at an angle slightly
greater than 17°.

The Moon visits Jupiter, and this time
the separation between planet and
Moon is slightly wider - nearly 5°.
However, given Jupiter's greater brightness (magnitude -2.1 on this date), this
pairing will be more striking than that
with Saturn for naked-eye observers.
Like Saturn, Jupiter is gradually becoming a more impressive telescopic sight,
as it now rises nearly two hours before
the Sun and climbs to an altitude of
15° half an hour before sunrise. Jupiter
is a rewarding world to inspect with
your scope, not least because of all the
comings and goings of its four brightest
satellites. Turn to page 51 to identify
which moon is which, and to see a listing of events - including several mutual
events in which the moons eclipse and
occult one another. The planet's array
of pastel belts and its Great Red Spot are

also endlessly fascinating, even in modest instruments.

FRIDAY, APRIL 16
Having slipped out of view after its
dawn encounters with Jupiter and
Saturn, the Moon reappears in the
evening sky as a waxing crescent. On
the 16th its journey along the ecliptic
brings it near the third and ﬁnal planet
of our April tour: Mars. On this night,
the Moon sits roughly 5° below the
1.4-magnitude Red Planet. Both objects
are positioned within the conﬁnes of
the Winter Hexagon - a large asterism
comprising the bright stars Aldebaran, Rigel, Sirius, Procyon, Pollux, and
Capella. With the temporary addition of
the Moon and Mars, this is a splendid
naked-eye vista high in the west during
fading evening twilight. If the weather
doesn't cooperate, try again the follow-

TX 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. The blue 10° scale bar is about the
width of your fist at arm's length. For clarity, the Moon is shown three times its actual apparent size.

Dusk, April 15 -17

Dusk, April 21- 22

45 minutes after sunset

1 hour after sunset

Moon
Apr 17

Dusk, April 25
30 minutes after sunset

Aldebaran

Mars
Pleiades

Sickle
10°

Moon
Apr 16

TA U R U S

Moon
Apr 21

LEO

TAURUS

Moon
Apr 22
Regulus
Aldebaran

Looking West,
halfway up

Mercury
Venus

Moon
Apr 15
Pleiades

APRIL 2 021 * SK Y & TELESCOPE

Looking South,
high in the sky

Looking West-Northwest

http://www.skyandtelescope.org

Sky & Telescope - April 2021

Table of Contents for the Digital Edition of Sky & Telescope - April 2021