Astronomy - USA (2020-01)

SKY THIS MONTH

Visible to the naked eye

Visible with binoculars

Visible with a telescope

Mid-January, 1 hour after sunset

Looking southwest

CAPRICORNUS

PEGASUS

AQUARIUS

Enif

Venus

Fomalhaut 10°

36 ASTRONOMY • JANUARY 2020

As 2020 opens, Venus

lights up the south-

western sky starting soon after

sunset. It undergoes a rare close

conjunction with Neptune dur-

ing January’s final week, when

the two worlds appear within

the same telescopic field of

view. But Neptune and its outer

solar system sibling, Uranus,

remain relatively easy evening

targets all month. Most of the

other planets inhabit the pre-

dawn sky. Mars rises first and

climbs clear of the southeastern

horizon by the time twilight

begins, while Jupiter and Saturn

reappear in late January.

Let’s begin our tour as the

sky starts to darken. The first

evening of the New Year finds

Venus shining brilliantly above

the southwestern horizon. The

magnitude –4.0 planet stands

16° high an hour after sunset.

A six-day-old waxing crescent

Moon appears high above it in

the south, while the seasonally

challenged stars of the Summer

Triangle dip low in the west

and northwest.

Venus then lies among the

faint background stars of cen-

tral Capricornus. But its steady

eastward motion this month

carries it into the equally

nondescript constellation

Aquarius on January 11. It

nears the Water-bearer’s east-

ern edge late in the month, set-

ting up a remarkable encounter

with Neptune. Venus serves as

a blazing signpost to help you

find the distant planet, par-

ticularly on the evenings of

January 26 and 27.

Here’s how to find the nor-

mally elusive Neptune: As

darkness falls on the 26th, tar-

get Venus with binoculars or a

telescope at low power. Note

the 4th-magnitude star Phi (φ)

Aquarii 1.4° above it. Neptune

lies two-thirds of the way from

Venus to Phi. The outer planet

appears as a faint dot, glowing

at magnitude 7.9. Don’t confuse

it with the slightly brighter star

that stands 0.5° to its right.

Neptune proves easier to

find the following night, when

it passes just 5' north of Venus

— the closest approach between

these two planets since January

1984. The conjunction occurs at
      2 p.m. EST, which places western
      Europe in the best viewing spot.
      By the time night falls across
      North America a few hours
      later, Neptune lies 12' west of
      Venus while Phi stands a nearly
      equal distance to Venus’ east-
      northeast. Although 10x50 bin-
      oculars will separate the three
      objects, Neptune may be a chal-
      lenge to see in Venus’ glare. A
      telescope shows the trio much
      more clearly.
      As if to draw attention to
      this extraordinary conjunction,
      a slender crescent Moon
      appears 7° below the two plan-
      ets. Imagers should take advan-
      tage of the opportunity to
      capture the scene with some
      attractive foreground objects.
      Although the two worlds
      appear near each other in our
      sky, a large expanse of space
      separates them. Venus resides

Venus lights up January evenings (^)
The brilliant inner planet dominates the southwestern sky from shortly after
sunset until it sets in midevening. ALL ILLUSTRATION: ASTRONOMY: ROEN KELLY
JANUARY 2020
Venus meets Neptune
THE SOLAR SYSTEM’S CHANGING LANDSCAPE AS IT APPEARS IN EARTH’S SKY.
BY MARTIN RATCLIFFE AND ALISTER LING
A bright Quadrantid meteor splits the sky
below the Big Dipper in this scene from
the peak of the 2016 shower. ALAN DYER