THE SOLAR SYSTEM IN JULY 2018

Dates and times shown are NZST (UT + 12 hours) unless otherwise stated. Times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.

      July  1         NZST          July 31         NZST  
      Mag  Cons    Rise    Set     Mag  Cons    Rise    Set
SUN  -26.7  Gem   7.45am  5.04pm  -26.7  Cnc   7.27am  5.27pm
Merc  -0.1  Cnc   9.10am  6.54pm    2.8  Leo   7.50am  6.48pm
Venus -4.1  Leo  10.10am  8.21pm   -4.3  Leo   9.25am  9.15pm
Mars  -2.2  Cap   7.02pm 10.06am   -2.8  Cap   4.26pm  7.58am
Jup   -2.3  Lib   1.30pm  3.27am   -2.1  Lib  11.33am  1.32am
Sat    0.0  Sgr   4.36pm  7.37am    0.2  Sgr   2.29pm  5.31am
Uran   5.8  Ari   2.18am  1.04pm    5.8  Ari  12.23am 11.07am
Nep    7.9  Aqr  10.27pm 11.20am    7.8  Aqr   8.27pm  9.09am
Pluto 14.4  Sgr   5.43pm  8.37am   14.4  Sgr   3.41pm  6.36am

              July  1  NZST              July 31  NZST
Twilights    morning     evening        morning     evening
Civil:    start 7.16am, end 5.33pm   start 7.01am, end 5.54pm
Nautical: start 6.42am, end 6.08pm   start 6.27am, end 6.28pm
Astro:    start 6.08am, end 6.41pm   start 5.55am, end 7.00pm
      JULY PHASES OF THE MOON, times NZST (& UT)
 
  Last quarter   July  6 at  7.51pm (07:51 UT)
  New moon:      July 13 at  2.48pm (02:48 UT)  solar eclipse
  First quarter: July 20 at  7.52am (Jul 19, 19:52 UT)
  Full Moon:     July 28 at  8.20am (Jul 27, 20:20 UT) eclipse

The moon eclipses the Sun on July 13, but the path of totality is off the Earth to the south. The northern edge of the partial eclipse area touches the north-most point of Stewart Island. From the most southerly point of the island a mere 1.4% of the Sun's disk is covered. A partial eclipses is also visible from the southern half of Victoria and Tasmania with the latter getting the best view.

The moon is totally eclipsed at the full moon of July 28. The initial stages of the eclipse are visible from New Zealand with the moon low to the west. It sets at about the time totality starts. Australia, especially the west, will get a better view

See also www.rasnz.org.nz/in-the-sky/eclipses-2018


PLANETS in July 2018

All five of the naked eye planets are readily visible during at least some part of the evening during July. After Venus, Mars will be the brightest especially at the end of the month.

MERCURY is at its annual evening best during July when it is easiest to see after sunset. At the start of July it will set 100 minutes after the Sun. With a magnitude -0.1 it should be readily visible by about 6pm. At that time the planet will have an altitude 7° as seen from Wellington. Venus will act as a marker, some 17° away to Mercury's upper right.

Mercury is at its greatest elongation, 26° east of the Sun, on the 12th when it sets about two and a quarter hours after the Sun. By then it will have dimmed slightly but still be at a respectable magnitude 0.4 and 11° above the horizon at 6.15pm, the end of nautical twilight. Its position relative to Venus will be little changed.

VENUS itself is a brilliant early evening object to the northwest. It sets 200 minutes after the Sun on the 1st and nearly 4 hours later on the 31st. The planet is in Leo and moves past Regulus during July. The two are closest on the 10th when they are only 1° apart. That night Regulus will be to the upper left of Venus. The changing position of Venus relative to the star will be obvious from night to night.

MARS is going to put on a brilliant display during July. It starts the month at magnitude 2.1, virtually as bright as Jupiter. Mars will then be best seen mid to late evening. It is at opposition on the 27th at magnitude -2.8, easily outshining Jupiter, presently at magnitude 2.1. The red planet is closest to the Earth on the last day of the month at the same magnitude. At its closest it will be 57.6 million km, 0.385 AU, from the Earth and have an angular diameter 24.3 arc-second.

This is the best opposition of Mars since August 2003. Unfortunately opposition will coincide with the full moon, which will be about 9° from the planet on the 27th and 28th. By the 31st the moon will have moved away from Mars.

JUPITER is in Libra during July. It is stationary on July 11 when the planet will be about 2° from the binocular double alpha Lib. After the 11th, Jupiter will start moving to the east back towards the double star. At the end of the month they will be about 1.5° apart.

The moon, almost two-thirds lit, will be some 5° below Jupiter on the 21st.

SATURN is near some of the brighter stars of Sagittarius. The near full moon is 2.5° from the planet on the 25th.

URANUS remains a morning object in Aires. By the end of July it rises shortly after midnight.

NEPTUNE, in Aquarius, rises about 10.30 pm at the beginning of July and two hours earlier by the 31st.

PLUTO, still in Sagittarius sets early evening by the end of July.

BRIGHTEST ASTEROIDS in JULY, magnitude, constellation, time of transit
                JULY 1                JULY 31   
             Mag  Cons   transit    Mag  Cons   transit
(1)  Ceres   8.8   Leo    4.10pm    8.9   Leo    2.59pm
(3)  Juno    9.8   Psc    7.41am    9.4   Cet    6.36am
(4)  Vesta   5.6   Oph   11.25pm    6.4   Oph    9.11pm

CERES is in Leo moving away from gamma Leo which it passed at the end of June. Venus, also in Leo, overtakes the asteroid on a parallel track during July. The two are closest in the 16th when Ceres will be 7° to the lower right of Venus as seen early evening

JUNO is a morning object which should be visible in binoculars by the end of July. It is less than 3° from Uranus early on the 5th.

VESTA starts the month some 10° from Saturn a distance increasing to 13° during the month. The nearly full moon is 3° from the asteroid on the 24th.

Brian Loader

 

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