Sky & Telescope - USA (2019-09)

44 SEPTEMBER 2019 • SKY & TELESCOPE

Mercury

Saturn

Uranus

Neptune

10 "

Sep 1 11 21 30

116 30

11630

16

16

Venus

Jupiter

Mars

SEPTEMBER 2019 OBSERVING
Planetary Almanac

The Sun and planets are positioned for mid-September; the colored arrows show the motion of each during the month. The Moon is plotted for evening dates in the Americas when it’s waxing (right

side illuminated) or full, and for morning dates when it’s waning (left side). “Local time of transit” tells when (in Local Mean Time) objects cross the meridian — that is, when they appear due south and

at their highest — at mid-month. Transits occur an hour later on the 1st, and an hour earlier at month’s end.

The table above gives each object’s right ascension and declination (equinox 2000.0) at 0h Universal Time on selected dates,

and its elongation from the Sun in the morning (Mo) or evening (Ev) sky. Next are the visual magnitude and equatorial diameter.

(Saturn’s ring extent is 2.27 times its equatorial diameter.) Last are the percentage of a planet’s disk illuminated by the Sun and

the distance from Earth in astronomical units. (Based on the mean Earth–Sun distance, 1 a.u. is 149,597,871 kilometers, or

92,955,807 international miles.) For other dates, see skyandtelescope.com/almanac.

PLANET VISIBILITY Mercury: hidden in the Sun’s glow all month • Venus: visible at dusk

after the 18th • Mars: hidden in the Sun’s glow all month • Jupiter: visible at dusk, sets mid-evening •

Saturn: visible at dusk, sets after midnight

PLANET DISKS have south up, to match the

view in many telescopes. Blue ticks indicate the

pole currently tilted toward Earth.

PEGASUS

CAPRICORNUS

AQUARIUS

Fomalhaut

Rigel

Betelgeuse

MAJORCANIS

PISCES

Sirius

ORION

Pleiades

CANCER TAURUS

Pollux

Castor

Procyon

GEMINI Vega

HERCULES

CYGNUS

LEO

HYDRA

SCORPIUS

OPHIUCHUS

SAGITTARIUS

AQUILA

ERIDANUS CETUS

ARIES

Arcturus

CORVUS

VIRGO

BOÖTES

LIBRA

Spica

Antares

10 am 8 am 6 am 4 am 2 am Midnight 8 pm 6 pm 4 pm 2 pm

LOCAL TIME OF TRANSIT

+30°

+40°

–10°

–30°

–20°

• 40°

+20°

+10°

+30°

–20°

–10°

–30°

–40°

(^10) RIGHT ASCENSION
h 8 h 6 h 4 h 2 h 0 h 22 h 20 h 18 h 16 h 14 h 12 h
DE
CL
IN
AT
IO
N
EQUATOR
+20°
10 pm
0°
ECLIP
TIC^
Saturn
Uranus
Neptune
Jupiter
2
9
Sept
5
19
25 22
Sept
13 –14
Venus
Mars
Mercury
44 SEPTEMBER 2019 • SKY & TELESCOPE
Date Right Ascension Declination Elongation Magnitude Diameter Illumination Distance
Sun 110 h 38.7m +8° 34′ —–26.8 31 ′ 41 ′′ —1.009
30 12 h 23.1m –2° 30′ —–26.8^31 ′^56 ′′ —1.002
Mercury^110 h 30.1m +11° 19′ 3° Mo –1.8 5.0′′ 99% 1.347
11 11 h 39.6m +3° 35′ 6° Ev –1.2 4.8′′ 98% 1.387
21 12 h 40.7m –4° 08′ 14° Ev – 0.5 5.0′′ 93% 1.356
30 13 h 30.9m –10° 27′ 19° Ev – 0.2 5.2′′ 86% 1.287
Venus 110 h 59.1m +8° 02′ 5° Ev –3.9 9.7′′ 100% 1.719
11 11 h 44.9m +3° 07′ 8° Ev –3.9 9.8′′ 99% 1.706
21 12 h 30.2m –1° 59′ 10° Ev –3.9 9.9′′ 98% 1.687
30 13 h 11. 2m –6° 32′ 13° Ev –3.9 10.0′′ 98% 1.666
Mars^110 h 42.2m +9° 23′ 1° Ev +1.7 3.5′′ 100% 2.675
16 11 h 17.8m +5° 40′ 5° Mo +1.8 3.5′′ 100% 2.664
30 11 h 50.7m +2° 05′ 9° Mo +1.8 3.5′′ 100% 2.641
Jupiter 116 h 54.5m –22° 14′ 97° Ev –2.2 39.0′′ 99% 5.055
30 17 h 07.0m –22° 37′ 72° Ev –2.0 35.9′′ 99% 5.492
Saturn^119 h 00.2m –22° 29′ 126° Ev +0.3 17.6′′ 100% 9.421
30 18 h 59.6m –22° 33′ 97° Ev +0.5 16.9′′ 100% 9.863
Uranus^162 h 14.9m +12 ° 5 9′ 137° Mo +5.7 3.7′′ 100% 19.088
Neptune 16 23 h 13.4m –6° 09′ 174° Ev +7.8 2.4′′ 100% 28.934
September Sun & Planets