The Solar System In October 2017

Dates and times shown are NZDT (UT + 13 hours) unless otherwise stated.

Sunrise, Sunset and Twilight Times in October

Times are for Wellington. They will vary by a few minutes elsewhere in NZ.

                    October  1  NZDT               October 31  NZST
       SUN: rise:   6.53am,  set:  7.28pm    rise:   6.06am,  set:  8.02pm
  Twilights     morning       evening            morning       evening
  Civil:    starts: 6.28am,  ends: 7.54pm    starts: 5.48am,  ends: 8.30pm
  Nautical: starts: 5.55am,  ends: 8.27pm    starts: 5.04am,  ends: 9.07pm
  Astro:    starts: 5.22am,  ends: 9.01pm    starts: 4.25am,  ends: 9.46pm

October Phases of the Moon (times NZST, as shown by GUIDE)

          Full moon:     October  6 at  9.40 am (Oct  5, 18:40 UT)
  Last quarter   October 13 at  1.26 am (Oct 12, 12:26 UT)
  New moon:      October 20 at  8.12 am (Oct 19, 19:12 UT)
  First quarter: October 28 at 11.22 am (Oct 27, 22:22 UT)

The Planets in October 2017

Four of the five naked eye planets will be close to the Sun during October. During the month Mercury reaches superior conjunction and Jupiter is at conjunction on the 27th. On the other hand Uranus is at opposition on the 20th. Saturn is the only naked eye planet readily visible - unless you can spot Uranus at magnitude 5.7.

Mercury is at superior conjunction at the far side of the Sun on October 9, NZ time. At conjunction Mercury will pass just under 1° north of the Sun. The planet will be 210.7 million km, 1.41 AU, from the Earth and 0.41 AU beyond the Sun.

Following conjunction the planet will become an evening object setting after the Sun. By the end of the month Mercury that will be an hour and a quarter later than the Sun. The planet, at magnitude -0.4, could just be visible some 45 minutes after sunset but very low at an altitude of 4.5° in a direction between midway between west and north west.

Venus is a very low morning object during October. On the 1st it rises 50 minutes before the Sun, by the 31st this will have reduced to just over 30 earlier. It will be about 4.5° up and to the east just before sunrise. On the morning of the 6th there is a close conjunction of Venus and Mars. The problem is that Venus will be only some 3° up at the start of civil twilight. If you have a good horizon to the east, Venus, Magnitude -3.9, should then be visible a little north of east. Mars will be only 12 arc minutes away, one-fifth of a degree almost directly above Venus. At magnitude 1.8 it is doubtful if it will be visible by eye, but binoculars should show it up. At Wellington the time of this is 6.20 am NZDT. At Auckland civil twilight starts about 4 minutes later with the planets about 4.5° up. At the other end of NZ, for Invercargill civil twilight starts at 6.38 am, but Venus will then be only 1.5° up.

Mars, now a morning object, rises 45 minutes before the Sun on October 1 and just over 70 minutes before the Sun on the 31st.as its distance from the Sun increases. This will make it a little more visible, but it will be only some 6° up at 5.30 am in Wellington. By then Mars will be 15° from Venus.

Mars starts October in Leo and moves into Virgo on October 12.

Jupiter starts October in the evening sky. On the 1st half an hour after sunset it will be some 11° up almost due west, with Spica 5° away to the lower left of the planet. Better views May be obtained a little while later, but Jupiter will set about 100 minutes after the Sun.

The planet will get steadily lower in the early evening sky during October to eventually get lost in twilight. Jupiter reaches conjunction with the Sun on the 27th, NZ time. At conjunction Jupiter will pass just under 1° north of the Sun. It will then be 963 million km, 6.43 AU, from the Earth and 5.44 AU beyond the Sun. After conjunction Jupiter becomes a morning object but will be too close to the Sun to see during the rest of October.

Saturn is readily visible in the evening sky during October although by the end of the month it will set a few minutes before midnight. The planet is in Ophiuchus moving away from Antares. On the 1st the two will be 13.5° apart, a separation increasing by 2° during the month.

The crescent moon passes Saturn on the evening of October 24. At 10 pm the two will be just over 4° apart with the moon below and to the right of Saturn. The magnitude 2.5 star eta Oph will be a similar distance away directly below the moon.

Outer Planets

Uranus is at opposition on the night of October 19/20 NZ time. The actual opposition is close to the time of the new moon. Uranus will be at its brightest, magnitude 5.7, and so May be visible to the naked eye from a dark sky site. Good eyesight will be needed. At least there will be no moon.

Uranus, in Pisces, will be 6° to the upper right of the magnitude 3.6 star eta Psc and 1.7° to the upper left of omicron, magnitude 4.3. At 10pm on the 19th, Uranus will be 23° up at azimuth 52° that is a little east of northeast. Uranus will transit just after 1am when it will be due north and at its highest, 39° up.

Neptune is also in the evening sky at magnitude 7.8 in Aquarius. On the night of October 3/4 the moon will occult Neptune for viewers in New Zealand. Times range from 12:16 at Invercargill to 12:42 at Auckland The moon will be near full, 94% lit, but the event should be visible with a modest telescope given Neptune's 7.8 magnitude.

The occultation will occur just a little north of centre on the moon unlit limb. The event will not be instantaneous, the disk of Neptune taking some 6.2 seconds to disappear completely.

Pluto, magnitude 14.4, remains in Sagittarius. It will be about a degree from the 2.9 magnitude star pi Sgr. As seen at 10 pm the planet will be almost directly above the star.

Minor Planets

(1) Ceres is a morning object in Cancer. It starts October at magnitude 8.8 and brightens slightly during the month to magnitude 8.6.

(2) Pallas is in Eridanus most of October but moves into Fornax on the 28th. During the month it brightens a little from magnitude 8.5 to 8.2. ON October 1 it rises close to 9 pm and set 14 hours later. By the end of October it rises at 6 pm and remains in the sky at Wellington for close to 15.5 hours.

(4) Vesta is in Virgo during October, magnitude 7.8 to 7.9. On the 1st it is only 5.2° from the Sun and virtually at conjunction. After the 1st it becomes a nominal morning object, but by the 31st will rise only 15 minutes before the Sun.

(7) Iris is in Aries throughout October, brightening from magnitude 7.7 to 6.9 during the month, making it the brightest asteroid all month. Iris's path in Aries takes it past the brightest star in the constellation, Hamal magnitude 2.00. On the 23rd Iris will be 1.4° to the upper right of the star as seen about 11 pm. Five nights later Iris will be at opposition, 127 million km, 0.85 AU from the Earth

Brian Loader  
New Zealand

The Solar System In September 2017

NZDT starts at 2am on the morning of September 24 when clocks should be advanced by 1 hour, bringing NZ time to UT + 13 hours. Dates and times shown are NZST (UT + 12 hours) until September 23 and then NZDT for the rest of the month, unless otherwise stated. The southern spring equinox is on September 23, NZ time, with the Sun crossing the celestial equator at about 8am.

Sunrise, Sunset and Twilight Times in September

Times are for Wellington. They will vary by a few minutes elsewhere in NZ.

                    September  1  NZST               September 30  NZDT
       SUN: rise:   6.43am,  set:  5.58pm    rise:   6.54am,  set:  7.27pm
  Twilights     morning       evening            morning       evening
  Civil:    starts: 6.18am,  ends: 6.24pm    starts: 6.29am,  ends: 7.53pm
  Nautical: starts: 5.46am,  ends: 6.56pm    starts: 5.57am,  ends: 8.26pm
  Astro:    starts: 5.15am,  ends: 7.28pm    starts: 5.23am,  ends: 8.59pm

September Phases of the Moon times (NZST/NZDT), as shown by GUIDE

          Full moon:     September  6 at  7.03 pm (07:03 UT)
  Last quarter   September 13 at  6.25 pm (06:25 UT)
  New moon:      September 20 at  5.30 pm (05:30 UT)
  First quarter: September 28 at  3.54 pm (02:54 UT)

The Planets in September 2017

The three terrestrial planets, Mercury, Venus and Mars, are all morning objects rising shortly before the Sun. Venus should be observable, especially early in the month. Mercury and Mars are not likely to be observable at any time.

Mercury rise 38 minutes before the Sun on September 1. The planet is at its greatest elongation 18° west of the Sun on the 12th but still rises only 39 minutes before the Sun. At the end of September, Mercury rises only 6 minutes before the Sun.

Venus starts off a little better than Mercury, rising nearly an hour and a half before the Sun. Half an hour before sunrise it will be some 9° up so easily visible as a low brilliant object. It will be well round to the north from east, The planet gets closer to the Sun as September progresses, so that by the 30th it will rise 50 minutes before the Sun. As a result, Venus will be then very low shortly before the Sun rises, and not as far to the north of east as at the beginning of the month.

Mars rises 23 minutes before the Sun on September 1. By the end of the month it will rise about 40 minutes earlier than the Sun and be 3.5° to the lower right of Venus. At magnitude 1.8 Mars and only a degree or two up half an hour before sunrise it is not going to be observable.

In the middle of the month the three terrestrial planets will form quite a tight group in Leo fairly close to Regulus. On the 18th they are joined by the Moon. In a period of just under 24 hours, the Moon will occult Venus, Regulus, Mars and Mercury as seen from some part of the Earth. The Venus event is visible, as a day time event, from all of Australia and New Zealand. At Wellington the time of disappearance is about 1:27 pm and the reappearance at 2:40 pm. The moon will be only a 6% lit crescent about 28° from the Sun. Binoculars are likely to show up the event, but the very thin crescent moon May be difficult to find.

Jupiter is visible in the early evening during September. It sets three and a half hours later than the Sun on the 1st, about 100 minutes later on the 30th so by then will be a low object to the west following sunset. Jupiter is in Virgo, close to Spica. At their closest on the 12th, the 1st magnitude star will be 3° to the left of the planet.

On the 22nd, the crescent moon will join the pair, when it will be just over 4° to the lower right of Jupiter. By then it would be best to be looking by 7pm or soon after. An hour later the three will be very low.

Saturn at least is visible all evening during September, although it will set about 1.40 am (NZDT) on the 30th. Saturn will be in Ophiuchus. Its encounter with the moon will be on the 27th, the moon being a day short of first quarter, about 5° to the right of Saturn mid evening.

Outer Planets

Uranus rises just before 10pm (NZST) on the 1st and close to 9 pm (NZDT) on the 30th. The planet is in Pisces at magnitude 5.7 throughout the month.

Neptune rises close to the time of sunset on September 1. By the 30th it will rise just after 5pm (NZDT) over 2 hours before the Sun sets. So it will then be well placed for viewing in the evening sky. The planet is in Aquarius at magnitude 7.8.

Pluto, magnitude 14.4, remains in Sagittarius. It will be just under a degree from the 2.9 magnitude star pi Sgr.

Minor Planets

(1) Ceres, a morning object starts the month at magnitude 9.0 in Gemini. On the 18th it will cross into Cancer brightening slightly during the month to magnitude 8.8.

(2) Pallas is in Eridanus rising at 10.20 pm on the 1st. During September it brightens from magnitude 9.0 to 8.5.

(4) Vesta is in Leo at first and then Virgo during September. As an evening object it will set too soon after the Sun for observation.

(7) Iris is in Aries throughout September, brightening from magnitude 8.5 to 7.7 during the month. It rises at 11:12 pm on the 1st and 10.33 pm on the 30th. It is quite close to Hamal, alpha Ari magnitude 2.0. Their separation is 2.1° on the 1st, increasing to 3.7° on the 24th after which Iris starts moving back towards Hamal.

(89) Julia is in Pegasus all month. It is at opposition at the beginning of September. For a few nights it will reach magnitude 9.0. On the 2nd it will form a near equilateral triangle with the stars zeta Peg (mag 3.4) and xi Peg (mag 4.2). Julia?s motion will take it past zeta, the two being 8 arc-minutes apart on the 8th. By the end of September Julia will have faded to magnitude 9.4.

Near Earth Object (3122) FLORENCE rapidly fades in early September as its distance from the Earth increases. On the 1st it will be at mag 8.9, 7 million km from the Earth and moving at about 24 arc-minutes per hour. The next two nights finds it in Delphinus, magnitudes 9.1 and 9.3 respectively. It is in Vulpecula at magnitude 9.6 on the 4th and in Cygnus at 9.9 on the 5th. By then Florence will be 8.4 million km away with an apparent speed 17 arc minutes per hour.

Brian Loader  
New Zealand