Astronomy

SOUTHERN

SKY

MARTIN GEORGE describes the solar system’s changing landscape

as it appears in Earth’s southern sky.

February 2016: Bright planets on display

As evening twilight fades in

early February, no bright plan-

ets grace the sky and observers

will have to be content with

viewing the glittering summer

stars. By late evening, however,

brilliant Jupiter rises in the

east. Now just a month away

from opposition and peak vis-

ibility, the giant planet gleams

at magnitude –2.4 and domi-

nates the overnight hours.

Jupiter resides among the back-

ground stars of southeastern

Leo, on the right end of the

upside-down creature where it

looks like an extension of the

Lion’s rear leg.

It’s best to wait until the

planet climbs higher in the sky

around midnight or later if you

want to observe it through a

telescope. The gas giant world is

well worth a look because of the

intricate detail in its cloud tops.

Even a small instrument reveals

an alternating series of bright

zones and darker belts that run

parallel to the equator. The

planet spans 44" at midmonth,

almost imperceptibly smaller

than its opposition diameter.

Also watch for night-to-night

changes in the pattern of its

four bright Galilean moons.

Nearly three hours after

Jupiter rises, ruddy Mars pokes

above the horizon. The Red

Planet travels eastward through

the dim constellation Libra the

Scales this month, moving

toward the head of Scorpius

the Scorpion. Mars’ strong

color makes it easy to identify,

but take care not to confuse it

with 1st-magnitude Antares,

Scorpius’ brightest star, which

rises somewhat later. The

planet shines noticeably

brighter than the star, increas-

ing from magnitude 0.8 to 0.3

during February.

Following a year in which

Mars appeared so small that

it showed little if any detail

through a telescope, it is now

starting to become attractive.

The planet’s disk grows from

6.8" to 8.6" across in February

and should reveal a few subtle

surface markings. Also see if

you can detect Mars’ phase,

which reaches a minimum of

90 percent lit this month.

About 90 minutes after

Mars rises, Saturn comes into

view. The ringed planet inhab-

its the constellation Ophiuchus

the Serpent-bearer, the little-

known 13th member of the

zodiac. (A nearly 20°-long slice

of the ecliptic — the Sun’s

apparent path across the sky

that the planets follow closely

— runs through Ophiuchus.)

At magnitude 0.5, Saturn

shines significantly brighter

than anything else in this

constellation.

The planet’s southerly dec-

lination makes it an attractive

target for telescope owners,

particularly once it climbs high

in the east before morning

twilight begins. Saturn’s disk

measures 16" across in mid-

February while the rings span

37" and tilt 26° to our line of

sight. In moments of good see-

ing, the dark Cassini Division

separating the outer A ring

from the brighter B ring should

appear obvious even through

small scopes. Also look for 8th-

magnitude Titan, Saturn’s big-

gest and brightest moon.

The parade of planets con-

tinues as the night wears on.

Brilliant Venus arrives next,

cresting above the eastern hori-

zon a bit more than two hours

before the Sun. Gleaming at

magnitude –3.9, the planet out-

shines every other celestial

object except for the Sun and

Moon. Still, the inner world is

moving away from Earth and

doesn’t look like much through

a telescope. All you’ll see is a

12"-diameter disk that is nearly

90 percent lit.

Mercury has crept away

from the Sun and now joins

Ve nu s i n F e b r u a r y ’s e a r l y

morning sky. Look for the

innermost planet to the lower

right of Venus all month.

Mercury reaches greatest elon-

gation February 7, when it lies

26° west of the Sun. It then

stands 11° high in the east-

southeast an hour before sun-

rise. Coincidentally, the waning

crescent Moon appears just to

the lower left of Mercury that

same morning. Through a tele-

scope, the planet’s disk then

spans 7" and appears slightly

more than half-lit.

The starry sky

As darkness falls on February

evenings, Orion the Hunter

stands tall in our northern

sky. In fact, this is one of the

few constellations that appears

prominent from both north

and south of the equator. If

you ignore the Hunter’s head,

sword, and shield, you can

envision him as an upright

figure even from the Southern

Hemisphere. Picture brilliant

blue-white Rigel and Saiph

as his shoulders or arms with

Bellatrix and ruddy Betelgeuse

as his legs.

Of course, things are not

that way. From our southern

perspective, Orion stands on

his head and his sword points

upward. People often remark

that Orion has a rather small

head for such a large body, but

it holds a lot of interest for

observers. The stars Lambda

(λ), Phi^1 (φ^1 ), and Phi^2 (φ^2 )

Orionis form the Hunter’s head.

They make a small triangle

with Lambda at the bottom.

Magnitude 3.4 Lambda Ori

is the brightest of the three and

has the proper name Meissa,

which comes from an Arabic

term meaning “The Shining

One.” Meissa is a fine double

star whose components shine at

magnitudes 3.6 and 5.5 and are

separated by a reasonably close

4.4". Moderately high magnifi-

cations split them quite easily.

Meissa is also the brightest

member of an open star cluster

known as Collinder 69, from

Swedish astronomer Per

Collinder’s catalog of 471

open clusters published in

1931. It covers about 1° of sky
      and shows up best through
      binoculars or a telescope with
      a wide field of view.
      There is much more to this
      part of the sky, however. A
      huge region of faint nebulosity
      that shows up only on photo-
      graphs surrounds Lambda. The
      so-called Lambda Orionis
      Nebula is a massive cloud of
      star formation that spans about
      10°. American astronomer
      Stewart Sharpless included it as
      number 264 in his second cata-
      log of emission nebulae. If we
      could see this glowing cloud
      with naked eyes, Orion’s head
      would look a lot bigger.