Sky & Telescope - USA (2020-01)

46 JANUARY 2020 • SKY & TELESCOPE

JANUARY 2020 OBSERVING

Sun, Moon & Planets by Fred Schaaf

qThese scenes are drawn for near the middle of North America (latitude 40° north, longitude 90°

west); European observers should move each Moon symbol a quarter of the way toward the one

for the previous date. In the Far E ast, move the Moon halfway. The blue 10° scale bar is about the

width of your fi st at arm’s length. For clarity, the Moon is shown three times its actual apparent size.

T

he year 2020 shapes up to be truly

spectacular for the planets.

Jupiter and Saturn will pull close

together in May, separate, and then

come back together in December to have

their tightest conjunction in centuries.

Also in 2020, Venus passes through

the Pleiades near the apex of an out-

standing evening apparition for observ-

ers at mid-northern latitudes. After

that, brilliant Venus moves over into

the morning sky for an almost equally

excellent dawn display.

Finally, Mars in 2020 glides close

past Jupiter and Saturn in March and in

the fall will appear almost as bright and

big in our sky as it was at the perihelic

opposition of 2018. But this time Mars

is 30° farther north and therefore much

Planetary Prelude

The fi rst month of this year provides a foretaste of some of the amazing sights to come.

sharper in telescopes for observers at

mid-northern latitudes.

Which planetary sights can you view

in this fi rst month of 2020? As Janu-

ary progresses, Venus comes into sight

higher and higher in the southwest at

nightfall. Mercury pokes into visibility

very low in the early evening twilight

near month’s end. But after Venus sets

around mid-evening no bright planet is

visible until several hours before sun-

rise, when Mars rises in Libra, Scorpius,

or Ophiuchus. The last two bright plan-

ets follow Mars up at dawn but are only

just emerging from the solar glare as

January progresses: Jupiter around the

second week of the month and Saturn,

just barely for lucky binocular observ-

ers, at month’s end.

DUSK TO MID-EVENING

Venus has a dramatic increase in

sunset altitude for observers at mid-

northern latitudes this month. If you

can already spot the planet’s intense

spark as the Sun drops below the hori-

zon, you’ll fi nd it about 25° above the

southwestern horizon on January 1st

and about 34° high on the 31st. The

interval between sunset and Venus-set

increases from 2¾ hours to almost 3½

hours during January. You should be

able to tell in your eyepiece that the

planet has a gibbous phase that shrinks

from 82% to 74% lit and a disk that

enlarges from 13′′ to 15′′ during the

course of January.

Venus spends the month track-

ing past Delta (δ) Capricorni (Deneb

• 
  

To fi nd out what’s

visible in the sky

from your location,

go to skypub.com/

almanac.

Dusk, Jan 3

45 minutes after sunset

CAPRICORNUS

Venus

Looking Southwest

10 °

b

`

_

Dawn, Jan 4

45 minutes before sunrise

Antares

Mars

Looking Southeast

SCORPIUS

α Lib

β

Dusk, Jan 6 – 8

1 hour after sunset

Aldebaran

Betelgeuse

ORION

TAURUS

Moon

Jan 6

Moon

Jan 8

Pleiades

Looking East, halfway up

Moon

Jan 7