0.5°Path of CeresFeb 1591317
21 25March 1CANCERfmm
m
moNEA dwarf planet comes to the foreThe Moon takes a bite from the Sun (^)
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If you’re new to tracking
objects in the asteroid belt,
Ceres offers a perfect starting
point. With just binoculars or a
small telescope, you can watch
this dwarf planet shift positions
relative to the background stars
from night to night, an unam-
biguous sign that it belongs to
our solar system.
To find Ceres, start with the
Star Dome map at the center
of this magazine. Locate the
bright stars Castor and Pollux in
Gemini just left of center and
then the constellation Cancer
the Crab closer to the eastern
horizon. The star at the north-
ern end of this pattern is 4th-
magnitude Iota (ι) Cancri, and
it’s the brightest object in the
chart below. From there, head a
few degrees northeast to the
four 5th- and 6th-magnitude
stars labeled Sigma^1 (σ^1 ) to
Sigma^4 (σ^4 ) Cancri. Just south
of them lies a relatively empty
region through which 7th-
magnitude Ceres slowly treks.
On a sheet of paper, sketch
a handful of the brightest stars.
Then, drop a tiny point into this
framework to represent which
object you suspect to be Ceres.
Refer to this page when you
return to the area a night or
two later. You should notice
right away that the dot marking
Ceres has moved.
We’re fortunate to live at a
time when we can connect this
moving mote of light to the
magnificent world being
revealed by the Dawn space-
craft. A few years ago, scientists
could only guess at what lies on
its surface — and no one
expected mountains of salt.
LOCATINGASTEROIDS
Ceres wanders the Crab’s claws
planet. You’ll find the Red
Planet against the backdrop
of Scorpius, 0.4° south of 2nd-
magnitude Beta (β) Scorpii
and 8° northwest of its stellar
look-alike, Antares. Mars’ east-
ward motion carries it into
Ophiuchus on the 8th, when a
fat crescent Moon lies between
it and Jupiter. The following
morning, a slimmer crescent
Moon appears 5° to Mars’
upper left. Astroimagers will
want to be ready February 24,
when the planet passes 15'
north of 9th-magnitude globu-
lar star cluster NGC 6287.
On February 10, Mars
passes 5° due north of Antares.
It’s a perfect morning to com-
pare the brightnesses and col-
ors of the two objects, and
come to understand why
ancient observers named the
star Antares, which literally
means “rival of Mars.”
The gap between Mars and
Earth closes during February,
and the ruddy planet brightens
as a result. It shines at magni-
tude 1.2 on the 1st, magnitude
1.0 on the 15th, and magnitude
0.8 on the 28th.
As Mars approaches Earth,
it also appears to grow larger
when viewed through a tele-
scope. It swells by nearly 20
percent in February, reaching
6.6" across by the end of the
month. Although still too
small to show much detail,
the planet’s diameter will be
nearly four times bigger by the
time it reaches opposition in
late July.
The final member of our
planetary trio rises just before
5 a.m. local time February 1.
Saturn climbs 10° above the
southeastern horizon an hour
before sunup and appears
obvious in the gathering dawn.
It shines at magnitude 0.6,
noticeably brighter than any
of the background stars in its
host constellation, Sagittarius.
It’s only real competition
comes when a slender crescent
Moon appears 2° above it the
morning of February 11.
Viewing conditions
improve noticeably by the end
of February, when Saturn
stands 15° high at the start of
twilight. First, scan the area
with binoculars and enjoy the
rich backdrop of the Milky
Way. Then, grab a telescope
and catch your first good
looks of the planet this year.
Any instrument should show
the planet’s 16"-diameter disk
wrapped in a glorious ring
system that spans 36" and tilts
26° to our line of sight. The
8th-magnitude dot you see
lurking beyond the rings is
Saturn’s largest moon, Titan.
Shortly after the Moon fin-
ishes its trek past the morning
planets, it passes in front of
the Sun. On the afternoon of
February 15, people in most of
Chile, Argentina, and Uruguay
can view a partial solar eclipse.
From the southern tip of
South America, the Moon
covers 35 percent of the
Sun’s diameter at maximum.
Greatest eclipse occurs in
Antarctica, where 60 percent
of the Sun will be hidden
from view. As with any partial
solar eclipse, use a safe solar
filter to view it directly.
Residents of southern South America can watch a partial solar eclipse
February 15, when the Moon obscures up to 35 percent of the Sun.
Ceres puts on a wonderful show in the night sky during February as it
treks across the northern reaches of Cancer the Crab.
Martin Ratcliffe provides plane-
tarium development for Sky-Skan,
Inc., from his home in Wichita,
Kansas. Meteorologist Alister
Ling works for Environment
Canada in Edmonton, Alberta.