Skywatch - 2021 - 16

F E BRUA RY | 2021
aran. Another fi st farther, and you've
got the Pleiades in your sights.
Sparkling conglomerations. The
Hyades and the Pleiades are clusters,
specifically open clusters, which are
loose collections of stars numbering
anywhere from a few tens to a few
thousand members. Not only do stars
in open clusters share the same physical spot in space, they also share the
same origin - they're all forged in the
same stellar furnace.
The Pleiades, also known as the
Seven Sisters, is a fun cluster to
explore. Most people can easily distinguish the fi ve brightest stars: Alcyone,
Atlas, Electra, Maia, and Merope.
For a real treat, whip out a pair
of binoculars. Now how many stars
do you see? You should easily be able
to add Taygeta and Celaeno to your
Pleiades tally, plus a few more fainter
cluster members. If you have access
to a telescope, the Seven Sisters oﬀer
a profusion of shimmering gems,
and if your sky is dark enough, you
might even see traces of the nebula
enshrouding them.
The Hyades, the V-shaped open
cluster that forms the face of Taurus,
the Bull, is poorer in numbers than
the Pleiades, with some 200 members

instead of around 3,000. It's the closest open cluster to us, lying at a distance of around 150 light-years. Even
if it appears as if Aldebaran is one of
the 200 Hyades, thanks to its prominent position at the left tip of the V, it's
actually just an unrelated foreground
star that lies much closer to us.
The Charioteer's clusters. Use both
hands side by side, fully extended
thumb to pinky, to trace a line
from the middle star in Orion's Belt
between his shoulder stars, Betelgeuse
and Bellatrix. That'll take you to
Capella, the brightest star in Auriga,
the Charioteer, and the sixth brightest star in the night sky. Auriga is also
home to three open star clusters, M36,
M37, and M38 - all visible in binoculars in a reasonably dark sky. A small
scope will readily reveal them. M36
and M37 are very similar in brightness, while M38 is slightly fainter. Try
putting your star-hopping skills to use
by starting from either Theta Aurigae
or Beta Tauri to locate the clusters.
You might wonder why a star that
looks as if it belongs to Auriga has a
Taurus designation: Beta Tauri was
also known as Gamma Aurigae until
the IAU had its fi nal say on constellation boundaries.

Dusk, Feb 18 -20

Dawn, Feb 27

1 hour after sunset

30 minutes before sunrise

Moon
Feb 20

Pleiades

Moon
Feb 19

Aldebaran

CAPRICORNUS

PLANETS IN
FEBRUARY
Mercury begins the month lost in the
Sun's glare. It emerges at dawn around the
19th, forming a tidy triangle with Jupiter
and Saturn very low in the east-southeast
in bright morning twilight. You'll need binoculars to catch all three planets. Throughout February, Mercury gradually climbs
higher and brightens to magnitude +0.2 by
month's end.
The long-running morning apparition
of Venus comes to an end in early February. After the 7th, it will be difﬁcult to pick
Venus out in twilight. However, if you use
binoculars, you should be able to follow the
planet for several additional weeks.
Now that Jupiter and Saturn have
vacated the scene, Mars has the evening
sky to itself as the lone naked-eye planet.
High in the south at dusk, at mid-month
it shines at magnitude +0.7 in the constellation Aries. At that time, the Martian
disk spans only 7″, which is too small for
surface markings to be readily seen in
most telescopes. On the evening of the
23rd, however, the Red Planet's eastward
motion carries it over the border into
neighboring Taurus.
Fresh from their late-January conjunctions with the Sun, Jupiter and Saturn
emerge as morning objects in February.
But you'll have to wait until the latter half of
the month before they'll be easy naked-eye
sights. At magnitude -2.0, Jupiter is obviously much brighter than nearby Saturn,
which shines at magnitude +0.7. That's
why Jupiter will be easier to spot than
Saturn, even though the ringed planet is
slightly higher.

Mars
Saturn

TA U R U S

Mercury

Moon
Feb 18

Jupiter

10°

Looking South,
almost overhead
p Mars

Looking East-Southeast

remains the only bright planet in the evening sky. From February 18th to the 20th, the Moon, the
Red Planet, orange Aldebaran, and the Pleiades will present a pretty tableau high in the south. Saturn and
Jupiter join Mercury in the morning sky toward the end of the month. You'll have to look low on the eastsoutheastern horizon to glimpse the planetary trio before the rising Sun washes it away.
16 SK Y WATCH 2021

Historical Events
2/3: Johann
Elert Bode
discovers the
globular cluster
M53, 1775

2/7: William
Herschel
discovers
NGC 4027,
1785

Skywatch - 2021

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