Sky & Telescope - July 2020 - 46

JULY 2020 OBSERVING
Sun, Moon & Planets by Fred Schaaf
To find out what's
visible in the sky from
your location, go to
skyandtelescope.org.

A Month of Oppositions
Jupiter, Saturn, Pluto, and Pallas are all at their best in July.

J

uly is one of the most exciting
months for planet watchers this
year. Jupiter and Saturn are paired at
their biggest and brightest all night;
Mars rapidly gains size and brightness
and is visible for the second half of
the night; and Venus burns at its most
brilliant as it passes through the Hyades
and leaps out of morning twilight.

ALL NIGHT

disk diameter peaks at 18.5″ this month
while its rings span 42″, with their tilt
increasing slightly to nearly 22°. In
early July, Jupiter and Saturn transit the
meridian at 2:00 and 2:30 a.m. local
daylight-saving time, respectively, and
about 11:45 p.m. and 12:20 a.m. at
month's end. By late July the two planets set well before sunrise.
Pluto reaches opposition in Sagittarius on July 15th, when it glows dimly
at magnitude 14.3. (For a ﬁnder chart,
turn to page 48.) A fourth notable world
at opposition this month is the asteroid
Pallas. It reaches this milestone on the
12th, when it peaks at magnitude 9.6 in
western Vulpecula.

Jupiter reaches opposition on July 14th,
followed by Saturn on the 20th. The
two mighty gas giants are both retrograding (moving westward with respect
to the background stars) and on the
3rd Saturn edges back into Sagittarius,
where Jupiter currently resides. Since
Jupiter is moving faster than Saturn,
MIDDLE OF NIGHT
the separation between the two planets
TO DAWN
increases from about 6° to more than
Mars dramatically increases in bright7½° during the month.
ness again this month, improving from
Jupiter shines at magnitude -2.7
magnitude -0.5 to -1.1. The apparent
almost all July but brieﬂy peaks at -2.8
diameter of the Red Planet grows from
around opposition. Saturn brightens
11.4″ to 14.5″, making it a bit larger
from magnitude 0.2
to 0.1 for a few weeks
around opposition.
July 3 - 6
Jupiter swells to its
Between 10 and 11 pm
Moon
largest diameter for the
July 3
year (47.6″) and offers a
wealth of detail visible
Moon
even in fairly small
July 4
α Cap
telescopes. Saturn's

than it appears during unfavorable,
aphelic oppositions. Yet Mars still has
three more months to brighten and
enlarge before its perihelic opposition
in October.
At the start of July, Mars rises
around 12:30 a.m. local daylight-saving
time - 1½ hours before Jupiter culminates. At the end of the month, Mars
comes up about 11:15 p.m.
Mars reaches the meridian after
sunrise in early July, but roughly half
an hour before sunrise in late July. On
the 11th, Mars ventures north of the
celestial equator for the ﬁrst time since
last October, making it respectably high
for observers at mid-northern latitudes
when the planet nears the meridian. The campﬁre-colored world drifts
north-eastward from Pisces through a
corner of Cetus in early July, before reentering Pisces at the end of the month.

Dawn, July 4
45 minutes before sunrise

Pleiades
10°

TAURUS
Venus

Jupiter

u 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

J U LY 2 0 2 0 * S K Y & T E L E S C O P E

Saturn

Aldebaran
Moon
July 5

S A G I T TA R I U S

Moon
July 6

Looking Southeast

Looking East
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Sky & Telescope - July 2020

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