46 JUNE 2020 • SKY & TELESCOPE
JUNE 2020 OBSERVING
Sun, Moon & Planets by Fred Schaaf
quThese 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 st at arm’s length. For clarity, the Moon is shown three times its actual apparent size.A
fter inferior conjunction on June
3rd, Venus makes a fairly steep
climb into morning twilight, appearing
two hours before sunrise by month’s
end. Now rising in the evening, Jupiter
and Saturn move 1° farther apart in
June, but are both brightening and get-
ting bigger as they approach their July
oppositions. As for Mars, it rises after
midnight but fl ames a half-magnitude
brighter during June and grows large
enough for major surface features to be
glimpsed in moderate-sized telescopes.DUSK TO LATE EVENING
Mercury is the only planet visible as
June’s long evening twilight begins to
fade. The innermost planet reaches
a greatest eastern elongation of 24 °Venus Returns
The brightest planet emerges at dawn after a near miss with the Sun.
from the Sun on the 4th. Mercury
then shines at magnitude +0.4 and
its 8 ′′-diameter disk is less than 37%
lit. The fl eet little planet sets more
than 1 hour and 45 minutes after
the Sun during the fi rst week of June.
But Mercury’s altitude and brightness
quickly begin to decrease. On the 12th
it shines at magnitude 1.3 well below
Pollux and Castor, and a few days later
it’s too dim and low to glimpse without
optical aid. Mercury reaches inferior
conjunction on July 1st.
Jupiter and Saturn rise within
about 15 minutes of each other in the
hour before midnight as June begins
but in the hour after sunset at the
end of the month. Both worlds are
slowly retrograding (moving westward)— Jupiter is a few degrees west of the
Capricornus-Sagittarius border, and
Saturn remains in Capricornus until
it crosses into Sagittarius on July 3rd.
The two gas giants begin June only 5°
apart, and the gap between them grows
to 6° by the end of June. They make for
a splendid pair with Jupiter’s blazing
brightness increasing marginally from
magnitude –2.6 to –2.7, and Saturn’s
from magnitude +0.4 to +0.2. Jupiter’s
feature-rich globe grows from 45′′ to
47 ′′, while Saturn’s rings span 40′′ and
are tilted more than 20° from edge-on.PRE-DAWN TO DAWN
Mars rises around 1:45 a.m. daylight-
saving time as June opens, and shortly
after 12:30 a.m. as the month closes.46 JUNE 2020 • SKY & TELESCOPE
To nd out what’s
visible in the sky from
your location, go to
skyandtelescope.org.Dusk, June 5
30 minutes after sunset
CastorProcyonPolluxGEMINIMercuryLooking West10 °Dawn, June 8 – 9
1 hour before sunriseJupiterSaturnMoon
June 8Moon
June 9Looking South-SouthwestDawn, June 17–19
30 minutes before sunriseAldebaranVenusMoon
June 17Moon
June 18Moon
June 19Looking East-NortheastPleiades