WHEN TO
VIEW THE
PLANETS
EVENING SK Y
Venus (west)
Uranus (west)MORNING SK Y
Mercury (east)
Mars (southeast)
Jupiter (southeast)
Saturn (southeast)42 ASTRONOMY • MARCH 2020
Luna enhances a planetary pageant
The Moon nearly overshadowed Jupiter (far right), Mars, and Saturn (far left) on
March 8, 2018. March 18 sees the same quartet more tightly grouped. RYAN IMPERIO
COMET SEARCH I Cruising through Cassiopeia
OBSERVERS AND IMAGERS
REJOICE: The brightening
Comet PanSTARRS (C/2017 T2) is
getting better every week as it
approaches its peak in early May.
If you prefer to see it during the
evening hours, you will have to
wait until Friday the 13th, when
the Moon’s glare doesn’t spoil
the view until after midnight.
This is the last weekend that
PanSTARRS is posing with the
picturesque Heart and Soul nebu-
lae in Cassiopeia. For electronic
detectors, it will appear as a green
fuzzball on a colorful background,
but for organic eyeballs, the
comet will look like a gray cotton
ball on a misty backdrop. For sub-
urban observers, the dirty snow-
ball is likely a challenge to spot
with even a 10-inch scope, but the
9th-magnitude nebulosity is quite noticeable when using a 4-inch scope under dark, country skies.
Well away from the city, an 8-inch aperture at a power of 200x will expose how the comet’s characteris-
tic shape differs from elliptical galaxies. Giving this a try with smaller instruments is also a great way to
improve your skills. PanSTARRS’ southern flank will be well-defined thanks to the solar wind and radiation
pressure pushing on the comet’s escaping gas and dust, creating a bow wave. The nucleus of the comet is
invisible behind the shroud of dust, but this inner coma may shine like a star within the overall glow. On the
northern side, the ball quickly spreads into the soft nothingness of empty space.This first-time visitor to the inner solar system should glow near 9th magnitude as
it heads northeastward against the backdrop of Cassiopeia.1°CASSIOPEIA¡fIC 1848 IC 1805Path of Comet
PanSTARRS31262116116
March 1NEComet PanSTARRS (C/2017 T2)
daylight time every morning
of March. It’s worth planning
to rise early and check them
out. March mornings host two
planetary conjunctions — one
between Mars and Jupiter set
against the backdrop of east-
ern Sagittarius on March 20,
followed by a second between
Mars and Saturn in western
Capricornus on March 31.
There’s a beautiful prelude
to the first conjunction when
the waning crescent Moon
stands about 2° away from
Jupiter and Mars, with the
planetary duo residing just
1.3° apart in the predawn sky
March 18. Search for Saturn
7° east of these two. By the
morning of March 19, the
Moon has passed to the east
of Saturn and stands 7° east-
southeast of the ringed planet.
The extraordinary plan-
etary show continues on the
morning of March 20, when
Jupiter and Mars are in con-
junction. The pair rises at
about 4 a.m. and climbs 10°
high in the southeast an hour
later. At this point, Mars sits
42' south of Jupiter. Jupiter
shines with a yellowish light at
magnitude –2.1, while Mars’
magnitude 0.9 orange glow
provides a lovely contrast.
Target the duo with a tele-
scope at low power, as both
are visible in the same field ofview. Mars’ diminutive disk
spans just 6", while Jupiter’s
disk measures an impressive
36". At a distance of 139 mil-
lion miles, Mars sits 50 percent
farther from the Sun than
Earth, while Jupiter is much
farther away at 511 millionmiles. Thanks to its small
angular size, you’ll be hard-
pressed to make out many vis-
ible features on the martian
surface. In contrast, Jupiter’s
cloud tops are bursting with
detail. Furthermore, the solar
system’s largest planet is joined
by at least three jovian moons.
Io enters eclipse around
5:30 a.m. EDT on March 20
and will remain hidden after
that. Jupiter’s classic pair of
dark equatorial belts are vis-
ible straddling the equator,
and more subtle dark belts lie
to their north and south. With
luck, you may even glimpse
Jupiter’s Great Red Spot dur-
ing this conjunction with
Mars. Though the Red Planet
and the Great Red Spot share a
similar hue, their colors are
due to different processes.The eastward motion of
Mars carries it between Jupiter
and Saturn through March 31,
when the Red Planet stands 56'
south of the ringed planet.
Saturn and Mars shine with a
similar magnitude: Saturn at
magnitude 0.7 and Mars at
magnitude 0.8. The brighter
Jupiter stands 6° west of this
majestic pair. Sadly, a tele-
scope again reveals a nonde-
script surface on 6"-wide Mars,SKY THIS MONTH — Continued from page 37