Printer Friendly

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.
COPYRIGHT 2018 All rights reserved. This copyrighted material is duplicated by arrangement with Gale and may not be redistributed in any form without written permission from Sky & Telescope Media, LLC.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2018 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Publication:Sky & Telescope
Date:Oct 1, 2018
Words:712
Previous Article:Harvest the Stars.
Next Article:The Sea Goat in the Skies: The ancient constellation Capricornus bears an interesting history.
Topics:

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters