56 ASTRONOMY • AUGUST 2020
Catch the two greatest telescopic
planets at opposition this month
and you’ll see beautiful planetary
worlds! BY STEPHEN JAMES O’MEARA
OBSERVE
Jupiter and Saturn at
his month promises
planetary observ-
ers their best views of Jupiter
and Saturn for the year as
both worlds reach opposition
within a week of one another.
Earth first moves directly
between Jupiter and the Sun
on July 14, then between
Saturn and the Sun on the
20th. Come opposition, thegas giants will be at their clos-
est and brightest for the year.
But opposition is more than a
moment in time; it is a chance
to seek out those brief win-
dows when the atmosphere
allows us to see fine details
— the most these planets can
display each year.
What’s more, we are pre-
sented on December 21 with
a rare opportunity to compare
and contrast Jupiter and
Saturn, our solar system’s two
largest planets, when they
approach within 6' of one
another in the sky. So, begin
familiarizing yourself with the
appearance of these worlds
through your telescopes, forwho knows how many per-
sonal or scientific discoveries
you’ll make! It is the very
nature of these two dynamic
gas giants to offer up surprises.
Because Jupiter reaches
opposition first, let’s look at
some of the unusual phenom-
ena that you can attempt to see
on the king of planets with the
naked eye and a telescope.Naked-eye sightings
of Jupiter
Shortly after opposition,
Jupiter enters the pre-sunset
sky, making it a perfect target
for daytime naked-eye sight-
ings. At opposition, Jupiter
will shine at magnitude –2.8,This Hubble Space Telescope image of
Saturn at opposition in October 1999
shows the planet’s rings tilted –20°. Look
carefully for the thread of shadow adjacent
to the planet’s ball. Also look for another
thread of shadow of the ring on the
planet’s southern hemisphere.
NASA AND THE HUBBLE HERITAGE TEAM (STSCI/AURA);
ACKNOWLEDGMENT: R.G. FRENCH
(WELLESLEY COLLEGE), J. CUZZI
(NASA/AMES), L. DONES
(SWRI), AND J. LISSAUER
(NASA/AMES)