1°cPath of
Comet PANSTARRS151413121110June 9SAGITTARIUS
M70M54NEComet PANSTARRS (C/2016 M1)15"
June 8, 1:05 A.M. EDTJupiterGanymedeS CallistoWIoGanymede emerges into sunlight42 ASTRONOMY • JUNE 2018
COMETSEARCH
Several periodic comets are slat-
ed to cross our summer and fall
skies. The best of the lot should
be Comet 46P/Wirtanen, which
may be visible to the naked eye
in late fall and early winter.
But plan to set your sights on
Comet PANSTARRS (C/2016 M1)
this month. The 10th-magnitude
object passes through the bot-
tom of Sagittarius’ Teapot aster-
ism in June’s second week. On
the 9th and 10th, it slides about
40' from the 8th-magnitude
globular star cluster M54. A few
nights later, it passes twice as far
from the similarly bright globu-
lar M70. The waning crescentMoon doesn’t rise until 3 A.M.
local daylight time on the 9th
and about a half-hour later each
succeeding night, so it won’t
hinder your quest.
You’ll want to observe
between 2 and 3 A.M., when
Sagittarius climbs highest in the
south. And you’ll probably need
a 6-inch or larger telescope and a
dark observing site to see it. The
light from PANSTARRS likely will
spread out enough to render it
invisible at low power. Crank the
magnification up to 100x or so to
pull it out of the background.
And if conditions allow, don’t
hesitate to add more power.Masquerading among the globulars
EVENING SKY MIDNIGHT MORNING SKY
Mercury (northwest) Mars (southeast) Mars (south)
Venus (west) Jupiter (southwest) Saturn (southwest)
Jupiter (south) Saturn (southeast) Uranus (east)
Saturn (southeast) Neptune (southeast)
WHEN TO VIEW THE PLANETS
— Continued from page 37
in early May, and it spends June
moving slowly westward rela-
tive to the background stars. It
begins the month 0.9° north-
northeast of Zubenelgenubi
(Alpha [α] Librae) and ends the
month 2° northwest of this 3rd-
magnitude star.
Although Jupiter’s diameter
shrinks from 44" to 41" during
June, that’s big enough to show
nice detail through any tele-
scope. Begin observing in early
evening when the gas giant
stands high in the south and
its light passes through less of
Earth’s atmosphere.
The first features to appear
are two dark belts that sand-
wich a brighter zone coinciding
with the gas giant’s equator.
Details along the belts’ turbu-
lent northern and southern
boundaries pop into view dur-
ing moments of good seeing.
night. It also shines brightest at
opposition, cresting at magni-
tude 0.0.
Saturn lies among the back-
ground stars of Sagittarius.
Binoculars reveal several out-
standing deep-sky objects in
its vicinity. On June 1, the
planet stands 1.9° northwest of
the 5th-magnitude globularThe planet’s four Galilean
moons also show up clearly
through small scopes. Be
ready to observe an intriguing
event the night of June 7/8.
Ganymede lies in Jupiter’s
shadow in early evening but
gradually returns to view
between Io and Callisto. At
12:40 a.m. EDT, Io and
Callisto appear 25" apart
southeast of the planet. If
you watch the space between
these moons, you’ll see
Ganymede emerge into sun-
light starting at 12:43 a.m. It
returns to full visibility by
1:02 a.m.
Saturn rises shortly after
10 p.m. local daylight time in
early June, but your best views
will come around the time it
reaches opposition June 27. It
then lies opposite the Sun in
our sky and remains visible allstar cluster M22 and 3.2°
south of the similarly bright
open cluster M25. The
Lagoon and Trifid nebulae
(M8 and M20, respectively)
lie 7° west of Saturn. By
month’s end, Saturn’s west-
ward motion brings it about
halfway between M25 and
M8. Unfortunately, a FullSagittarius’ Teapot hosts two 8th-magnitude globular clusters, M54 and
M70, that provide an enticing backdrop for this Oort Cloud visitor.The solar system’s largest moon materializes out of the darkness between
Io and Callisto when it exits Jupiter’s shadow the night of June 7/8.