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Path of CeresDec. 1 5 1015 2025
301°/e alNGC 1554/5Dec. 31, 1 hour before sunrise
Looking southeastSCORPIUSOPHIUCHUSLIBRAZubenelgenubiMoonMars
AntaresMarfik10°WWW.ASTRONOMY.COM 39
LOCATING ASTEROIDS I
Ceres from the city
WHILE DWARF PLANET 1 CERES quickly crossed the star-
studded face of Taurus the Bull last month, it now begins a stroll
into the populated Milky Way. The space rock is perfect for
binoculars from the suburbs, having just peaked at magnitude 7
on Nov. 29 during opposition.
As bright as Ceres is, it can almost hide in the crowd. Scan the
chart below or print out a larger-scale copy to mark when you
saw it. Use the 6th-magnitude stars as your pattern anchor to
positively identify the right dot.
It was back in 1801 that Giuseppe Piazzi was comparing tele-
scope fields with star charts and picked out this undiscovered
planet. Like him, wait a night or two to confirm its motion against
the background. At month’s end, Ceres has faded a whole magni-
tude, but is easier to spot in the sparser starfield.
Earth now pulls ahead on its inside track, lapping Ceres in 2023.
The paths are not round, however, which will bring the main-belt
asteroid slightly closer to Earth than it’s been since 2005. These
brighter oppositions come in cycles of nine and 14 years.Lost in the crowd (^)
darkness falls. Io’s transit ends
at 9:14 P. M. EST, followed by its
shadow 75 minutes later. Two
days later, Ganymede, Jupiter’s
largest moon, transits on Dec. 7
beginning at 9:03 P. M. EST. The
event continues for more than
3 hours.
Neptune is a binocular
object shining at magnitude 7.8
most of the month and located
in Aquarius the Water-bearer. It
stands high in the southern sky
Dec. 1 and remains visible all
evening until it drops very low
after 11 P. M. local time. The dis-
tant planet lies 3° northeast of
the 4th-magnitude star Phi (φ)
Aquarii on Dec. 1. That night,
Neptune is at its stationary
point; it barely moves all month.
Neptune stands 4.5° north of a
First Quarter Moon on Dec. 10.
At the ice giant’s huge dis-
tance of nearly 30 astronomical
units (where 1 astronomical
unit or AU is the average Earth-
Sun distance) from us, its disk
spans only 2" through a tele-
scope. Use high magnification
on a steady night of seeing to
reveal its bluish-green disk.
Uranus stands high in the
sky against the backdrop of
Aries the Ram every evening
and sets in the early morning
hours. It lies about 11° south-
east of Hamal, the brightest
star in Aries. Uranus shines at
magnitude 5.7, an easy object
for binoculars once you find
the right field of view. The ice
giant stands about 3° northeast
of the gibbous Moon on
Dec. 14.
December is a great time to
view Uranus with a telescope,
given its high altitude after
dark. Uranus spans 4" with a
distinctive greenish-blue hue.
At a distance of 1.7 billion miles
(19 AU), it’s a wonder to behold.
Mars reappears in the morn-
ing sky in Libra and crosses
into Scorpius midmonth, then
moves into Ophiuchus Dec. 25.
That morning, it shines at
magnitude 1.6 less than 5°
north of its noted rival,
Antares, which is the brighter
of the two (magnitude 1.1).
Mars rises nearly two hours
before the Sun, so look for it
low in the southeast as twilight
begins. On the last morning
of the year, a waning crescent
Moon stands within 4° of Mars
and Antares — a beautiful sight
in the predawn sky.
The winter solstice occurs
Dec. 21 at 11 A.M. EST.
A total solar eclipse takes
place Dec. 4 across Earth’s
southern pole. The longest
duration of totality is 1 minute
54 seconds. A number of
cruises are slated to travel to
locations along the eclipse
track. The eclipse begins at sun-
rise in the South Atlantic Ocean
and crosses Coronation Island,
Red-letter day (^)
the largest of the South Orkney
Islands. The eclipse path then
crosses the Weddell Sea and
makes landfall again on the
Ronne Ice Shelf and Berkner
Island. A small partial eclipse
of the Sun will be visible across
southern Africa, Tasmania, and
southern Australia.
GET DAILY UPDATES ON YOUR NIGHT SKY AT
http://www.Astronomy.com/skythisweek.
Martin Ratcliffe is a
planetarium professional with
Evans & Sutherland and enjoys
observing from Wichita, Kansas.
Alister Ling, who lives in
Edmonton, Alberta, is a longtime
watcher of the skies.
To track Ceres through this crowded region, choose several stars as
anchor points to catch the bright spot that moves.
Mars and the Moon give 2021 a grand send-off in Scorpius, where they hang
near the famously red-hued star Antares.