OCTOBER 2018 OBSERVING: Planetary Almanac.
Caption: PLANET DISKS have south up, to match the view in many telescopes. Blue ticks indicate the pole currently tilted toward Earth.Caption: The Sun and planets are positioned for mid-October; 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.
PLANET VISIBILITY Mercury: hidden in the Sun's glow
all month * Venus: visible at dusk through the 7th * Mars:
visible at dusk, sets after midnight * Jupiter: visible at
dusk, sets early evening * Saturn: visible at dusk,
sets mid-evening
October Sun & Planets
Date Right Ascension Declination
Sun 1 [12.sup.h] [27.6.sup.m] -2[degrees]59'
31 [14.sup.h] [19.6.sup.m] -13[degrees]56'
Mercury 1 [12.sup.h] [56.8.sup.m] -5[degrees]27'
11 [13.sup.h] [55.6.sup.m] -12[degrees]27'
21 [14.sup.h] [52.4.sup.m] -18[degrees]16'
31 [15.sup.h] [46.9.sup.m] -22[degrees]32'
Venus 1 [14.sup.h] [21.8.sup.m] -21[degrees]19'
11 [14.sup.h] [20.5.sup.m] -21[degrees]52'
21 [14.sup.h] [05.4.sup.m] -20[degrees]13'
31 [13.sup.h] [44.6.sup.m] -16[degrees]34'
Mars 1 [20.sup.h] [36.3.sup.m] -22[degrees]37'
16 [21.sup.h] [03.0.sup.m] -20[degrees]02'
31 [21.sup.h] [34.1.sup.m] -16[degrees]56'
Jupiter 1 [15.sup.h] [18.4.sup.m] -17[degrees]29'
31 [15.sup.h] [43.2.sup.m] -19[degrees]01'
Saturn 1 [18.sup.h] [12.0.sup.m] -22[degrees]46'
31 [18.sup.h] [20.0.sup.m] -22[degrees]47'
Uranus 16 [1.sup.h] [54.8.sup.m] +11[degrees]10'
Neptune 16 [23.sup.h] [02.1.sup.m] -7[degrees]16'
Date Elongation Magnitude Diameter
Sun 1 -- -26.8 31'57"
31 -- -26.8 32'13"
Mercury 1 8[degrees]Ev -0.9 4.8"
11 14[degrees]Ev -0.4 4.9"
21 19[degrees]Ev -0.2 5.3"
31 22[degrees]Ev -0.2 5.9"
Venus 1 33[degrees]Ev -4.8 46.2"
11 24[degrees]Ev -4.6 53.9"
21 11[degrees]Ev -4.2 59.9"
31 9[degrees]Mo -4.2 60.9"
Mars 1 118[degrees]Ev -1.3 15.8"
16 110[degrees]Ev -1.0 13.7"
31 103[degrees]Ev -0.6 12.0"
Jupiter 1 44[degrees]Ev -1.8 32.6"
31 21[degrees]Ev -1.7 31.4"
Saturn 1 85[degrees]Ev +0.5 16.5"
31 57[degrees]Ev +0.6 15.7"
Uranus 16 172[degrees]Mo +5.7 3.7"
Neptune 16 142[degrees]Ev +7.8 2.3"
Date Illumination Distance
Sun 1 -- 1.001
31 -- 0.993
Mercury 1 98% 1.406
11 93% 1.365
21 86% 1.276
31 75% 1.138
Venus 1 17% 0.361
11 8% 0.310
21 2% 0.278
31 1% 0.274
Mars 1 88% 0.592
16 87% 0.682
31 86% 0.781
Jupiter 1 100% 6.046
31 100% 6.285
Saturn 1 100% 10.097
31 100% 10.563
Uranus 16 100% 18.884
Neptune 16 100% 29.153
The table above gives each object's right ascension and declination
(equinox 2000.0) at [0.sup.h] 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.
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| Publication: | Sky & Telescope |
|---|---|
| Date: | Oct 1, 2018 |
| Words: | 712 |
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