The Solar System in October 2015

Dates and times shown are NZDT (UT + 13 Hours) unless otherwise stated. Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.

Sunrise, sunset and twilight times in October

                    October  1  NZST                 October 31  NZDT
                    morning  evening                 morning  evening
       SUN: rise:   6.54am,  set:  7.28pm    rise:   6.07am,  set:  8.02pm
Twilights
  Civil:    starts: 6.29am,  ends: 7.54pm    starts: 5.40am,  ends: 8.30pm
  Nautical: starts: 5.56am,  ends: 8.26pm    starts: 5.04am,  ends: 9.06pm 
  Astro:    starts: 5.23am,  ends: 9.08pm    starts: 4.26am,  ends: 9.45pm

October PHASES OF THE MOON (times as shown by GUIDE)

  Last quarter:  October  5 at 10.06 am (Oct  4, 21:06 UT)
  New moon:      October 13 at  1.06 pm (00:06 UT)
  First quarter: October 21 at  9.31 am (Oct 20, 20:31 UT) 
  Full moon:     October 28 at  1.05 am (Oct 27, 12:05 UT)

Lunar occultations of planets

An occultation of Venus by the moon on the morning of October 9 will be visible from New Zealand. Despite being a day time event, the occultation should be readily visible in binoculars or a small telescope and probably with the unaided eye for those with good vision.

Later in the month, on the evening of October 26, the moon, only one day short of full, will occult Uranus, again visible from most of New Zealand.

More information on these events is given in the section for the planet.

The planets in October

Only Saturn is visible in the evening sky, best viewed following sunset as the sky darkens. Mercury remains too close to the Sun to observe all month, while Venus, Mars and Jupiter have a get together in the dawn morning sky,

Mercury is at inferior conjunction between the Earth and Sun on the morning of October 1 at about 4 am. At conjunction the planet will pass about 2.4° south of the Sun and as seen from the Earth. Mercury will be 0.656 AU, 98 million km from the Earth and 0.347 AU, 52 million km from the Sun.

After conjunction, Mercury becomes a morning object rising before the Sun. At its best, in mid October, the planet will rise 30 minutes before the Sun; by the end of October only 20 minutes earlier. In effect Mercury will not be visible at any time during the month.

Venus, MARS and JUPITER in the morning sky during October.

The three planets will start the month well spread out in the dawn sky.

Venus will be readily visible as a brilliant point of light in the dawn sky throughout October. It rises 2 hours before the Sun on the 1st, reducing to about 105 minutes earlier by the 31st. It will be the furthest of the three from the Sun at the start of October.

Mars rises some 75 minutes before the Sun on the 1st, and 100 minutes earlier on the 31st, so then little different to Venus.

Jupiter rises 1 hour before the Sun on the 1st, almost 2 hours earlier on the 31st. So it starts October as the closest of the 3 planets to the Sun and ends the furthest.

As a result of these changing positions there will be some close passes during the month. On the morning of October 18.Mars and Jupiter will be 24' apart, a little less than the diameter of the full moon. Mars, magnitude 1.7 will be to the lower left of the far brighter Jupiter (-1.8). The planets will be low while the sky is still dark enough to see them. Half an hour before sunrise Mars will be just 9° up as seen from Wellington. At magnitude 1.7 Mars is likely to be difficult to see but Jupiter should be fairly easy to spot, at an azimuth nearly 20° to the north of east. Binoculars will then show Mars if it is not visible to the eye. The elongation of the planets, 40° from the Sun, means the worst of the glare should be to the right of the planets

Eight mornings later, on the 25th, Venus will be 1° above Jupiter. Half an hour before sunrise Jupiter will be some 12° up, so now a little better placed. The brightness of Venus will make locating the pair simple.

Finally the last morning of October will find Mars some 1.7° to the lower right of Venus. This is not their closest approach: that will be on October 3.

The crescent moon will pass Mars and Jupiter on the morning of October 10 when it will be at the apex of a triangle formed by it and the two planets defining its base. The moon, 9% lit, will be just under 3° from each of the planets. The three will be low with the moon a little over 7° up 40 minutes before sunrise.

OCCULTATION of VENUS, morning of October 9, NZDT

In NZ the occultation takes place well after sunrise. Even so both phases of the occultation will be observable with binoculars or a small telescope. The light intensity of Venus will exceed that of the sunlit edge of the moon making the disappearance against the moon's lit limb observable. For New Zealand the occultations will take place fairly centrally round the moon's limb. The moon will be a 15% lit crescent

It will take about 90 seconds for the moon to cover the full diameter of Venus (30 arc second). But Venus will be only 40% lit, with the moon covering and exposing the unlit half first. Hence from the observer's point of view the occultation will start at about the time given in the table below for the mid event. The lit portion of Venus will be hidden or exposed to view over the following three-quarters of a minute.

The predicted times (NZDT am) for a number of places in NZ are given below, D = Disappearance and R = Reappearance:

Auckland:      D 8:11:59,  R 9:52:32
Hamilton:      D 8:14:35,  R 9:54:33
Palmerston N:  D 8:20:14,  R 9:57:26
Wellington:    D 8:20:34,  R 9:56:01
Nelson:        D 8:17:51,  R 9:52:16
Christchurch:  D 8:21:35,  R 9:52:01
Dunedin:       D 8:23:31,  R 9:48:01
Invercargill   D 8:21:44,  R 9:43:22

Times for other places will of course vary, even in different parts of the same city. Those who have the Occult program should generate their own predictions, otherwise Venus should be easily visible, weather permitting, a few minutes before the disappearance.

The occultation is also visible from the eastern half of Australia where the disappearance occurs in a dark sky and the reappearance around the time of sunrise.

Saturn will be the only naked eye planet in the evening sky. It sets just before midnight on the 1st and soon after 10pm on the 31st. So even it will be low especially by the end of the month when it will set an hour after the end of nautical twilight (Sun 13° below the horizon)..

The planet starts the month in Libra but crosses into Scorpius on the 17th. Saturn will be about 10° below Antares, getting a little closer as the month progresses.

The 10% lit crescent moon will be about 5° below Saturn on the 16th. The following night it will be 9° to the upper right of Saturn.

Outer planets

Uranus is in Pisces during October, being at opposition on October 12. It will then be 19.0 AU, 2840 million km from the Earth and 20 AU, 2992 million km from the Sun. Being at opposition mid October means it is in the dark sky all night throughout the month.

OCCULTATION OF URANUS. On the evening of October 26 an occultation of Uranus by the moon will be visible in NZ for places from just north of Auckland southwards. A grazing occultation occurs just south of Wellsford. The path of the graze is very close to the one for the graze of Uranus on the morning of September 2.

At the October graze the disappearance will be nominally at the unlit limb of the 98.3% sunlit moon, near its north pole. With the moon so near full, the disappearance of Uranus will be very close to the terminator of the sunlit region, especially in the northern half of the North Island.

Times of the disappearance vary from 11:09:17 at Auckland, the planet taking 36.2 seconds to completely disappear, to Hamilton 10:03:36 (21.4 seconds), Wellington 10:52:39 (12.8 seconds), Christchurch 10:46:54 (11.4 seconds), Dunedin 10:41:58 (10.4 seconds) and Invercargill 10:35:59 (10.4 seconds). The times are for the 50% occultation of the planet.

The reappearance takes place some time later ranging from 11:26:26 at Auckland where the planet will be behind the moon for just over 17 minutes to 11:30:54 at Invercargill with Uranus behind the moon for 55 minutes. This will be at the sunlit limb of the moon.

Neptune was at opposition at the beginning of September, so it will be visible all evening throughout October. The planet will continue to be in Aquarius at magnitude 7.8 to 7.9, so is quite easily seen in binoculars. The 77% lit gibbous moon is closest to Neptune on October 23 when the planet will be 6° to the right and rather higher than the moon. The following night the two will be 10.5° apart with Neptune to the moon's upper left.

Pluto continues to be in Sagittarius all October with a magnitude 14.4.

Brighter asteroids:

(1) Ceres is in Sagittarius during October its magnitude ranging from 8.7 to 9.1. Ceres will be moving to the east through Sagittarius towards the constellation's triple boundary point with Microscopium and Capricornus

(4) Vesta is in Cetus throughout October its magnitude ranging from 6.2 to 6.9 during the month. It is at opposition on October 3, when it is brightest. The asteroid will be moving to the west, 9 to 10° from beta Cet, Diphda (magnitude 2.0). On the 17th it will be on the line from beta Cet to iota Cet (3.5), with Vesta a little under 2° from the latter.

(15) Eunomia is in Pegasus during October its magnitude varying from 8.0 to 8.3 as the Earth moves away from the asteroid following its end of October opposition. The asteroid moves in an arc through Pegasus more or less centered on gamma Peg (2.8), 8.4° away.

(29) Amphitrite starts October at magnitude 9.3 in Aries. It is at opposition on the 23rd at magnitude 8.7 and crosses into Pisces 4 nights later. By the end of October its magnitude will be back to 8.9. During October, Amphitrite will be moving to the west about 3° from beta Ari (2.6). On the 23rd, gamma Ari (4.6) will be close to midway between beta and Amphitrite.

(471) Papagena will be at opposition in Cetus on October 21 with a magnitude 9.5. It will then be 1.5° from tau Cet (3.5) The two are closest on the 17th with Papagena 1.26° to the lower left of the star.

Brian Loader

The solar system in September 2015

Dates and times are NZST (UT + 12 hours) unless otherwise specified up to September 26. From September 27 they are NZDT (UT + 13 Hours). NZDT commences on Sunday September 27 at 2am when clocks should be put forward one hour.

Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.

The southern spring equinox is on September 23, with the Sun on the celestial equator at 8:21 pm

Sunrise, sunset and twilight times in September

                     September  1  NZST                 September 30  NZDT
                    morning  evening                 morning  evening
       SUN: rise:   6.44am,  set:  5.58pm    rise:   6.55am,  set:  7.27pm
Twilights
  Civil:    starts: 6.19am,  ends: 6.24pm    starts: 6.30am,  ends: 7.53pm
  Nautical: starts: 5.47am,  ends: 6.56pm    starts: 5.58am,  ends: 8.25pm 
  Astro:    starts: 5.15am,  ends: 7.28pm    starts: 5.24am,  ends: 8.59pm

September PHASES OF THE MOON (times as shown by GUIDE)

  Last quarter:  September  5 at  9.54 pm (09:54 UT)
  New moon:      September 13 at  6.41 pm (06:41 UT)
  First quarter: September 21 at  8.59 pm (08:59 UT) 
  Full moon:     September 28 at  3.51 pm (02:51 UT)

Eclipses

A partial eclipse of the Sun on September 13 will be visible from southern parts of Africa, the southern half of the Malagasy Republic, the South Indian Ocean and Antarctica. No part of the eclipse is visible from Australia of New Zealand. This is an annular eclipse but the path of annularity misses the Earth.

A total eclipse of the moon on September 28 is also not visible from Australasia. The total phase of the eclipse, lasing some 82 minutes, is best seen from countries either side of the Atlantic Ocean.

The planets in September

Mercury will be well placed for evening viewing during the earlier part of the month. Venus, Mars and Jupiter are all morning objects rising a little before the Sun. Saturn, in the evening sky, will set before midnight. An occultation of Uranus by the moon on the morning of September 2 will be visible from most of NZ.

Mercury is an easy early evening object during the first half of September, setting 2 hours or more after the Sun. On the 1st, 50 minutes after sunset the planet, magnitude 0.2, will be some 15° above the horizon to the west. On the 4th Mercury is at its greatest elongation 27° east of the Sun. For nearly two weeks after that its evening altitude slowly declines as its easterly motion through the stars slow. Then on the 17th the planet is stationary before starting to move back to the west, following a path through the stars close to the one it took in the first part of September.

The return means the distance of Mercury from the Sun rapidly declines in the latter part of September as does its evening altitude so that it slips out of view. Mercury is at inferior conjunction between the Earth and Sun at the very end of the month. The actual conjunction is at about 4 am on the morning of October 1.

Venus was at inferior conjunction mid August, so September find it moving up into the morning sky. It rises nearly 100 minutes before the Sun on September 1. On the 5th Venus is stationary, after which it will start moving east towards the Sun. But the Sun itself will be moving to the east through the stars a little more rapidly. As a result the time Venus rises before the Sun will continue to slowly increase, up to almost 2 hours earlier on the 30th.

Venus starts the month in Cancer. Its easterly motion takes it into Leo on the 24th. Before that on the morning of the 10th the 11% lit crescent moon with be 7° to the left of Venus.

Mars is also a morning object, but rather lower than Venus. It rises just under an hour before the Sun on the 1st and 70 minutes before the Sun on the 30th. Mars will be at magnitude 1.8 all month.

Like Venus, Mars starts the month in Cancer, moving on into Leo on the 6th. In Leo it will move towards Regulus, alpha Leo, and is closest to the magnitude 1.4 star on the morning of September 25, when the two will be about 50 arc-minutes apart. Mars, at magnitude 1.8 will be slightly fainter than Regulus and to the lower left of the star.

The moon, a 6% lit waning crescent, will be just under 4° above Mars on the morning of the 11th, one day after it passes Venus.

Jupiter is the third planet in the morning sky that rises shortly before sunrise. It is in Leo all month, moving away from Regulus. It was at conjunction with the Sun on August 26, so will rise only 3 minutes earlier than the Sun at the beginning of September. By the end of the month this will have increased to nearly an hour before the Sun, but the planet will be only 5° above the horizon twenty minutes before sunrise making it a difficult object to see.

Saturn will be the only naked eye planet left in the evening sky once Mercury has slipped out of it. It sets at 12.40 am at the beginning of September and 11.56 pm (NZDT) on the 30th. Hence it will be readily visible in the earlier part of the evening. It will be in Libra about 12° below Antares all month, Saturn moving slightly closer to Antares as the month progresses.

The moon a 29% broad crescent will be some 3.5° to the right of Saturn on September 19.

Outer planets

Uranus remains in Pisces during September. It rises around 9.14 pm on the 1st and 8.15 pm (NDST) on the 30th. The planet will be at magnitude 5.7 so readily seen in binoculars.

OCCULTATION OF URANUS. On the morning of September 2 an occultation of Uranus by the moon will be visible in NZ for places just north of Auckland southwards. A grazing occultation occurs just south of Wellsford. The disappearance will be at the bright limb of the of the 88% lit moon so difficult to observe. The reappearance at the unlit limb will be a lot easier to see using a small telescope.

Unlike stellar occultations, the occultation of Uranus will not be instantaneous due to the angular diameter of the planet. In the South Island the reappearance will take about 6 seconds, but this time will increase further north, nearer the graze path, to almost 20 seconds at Auckland.

The time of the reappearance is near 5 am; for most places a little before, but for Wellington and places near the east coast of the North Island Uranus will reappear shortly after 5am. Users of Occult will be able to generate accurate times for their position.

A second lunar occultation of Uranus occurs on September 29. It is only visible from the south of South Africa, the ocean areas to the south and parts of Antarctica.

Neptune is at opposition on the 1st. It then rises 15 minutes before sunset and sets a few minutes after sunrise. By the end of the month Neptune sets an hour before sunrise. The planet remains in Aquarius at magnitude 7.8, so is quite easily seen in binoculars. The near full moon is closest to Neptune on September 26.

Pluto continues to be in Sagittarius all September with a magnitude 14.3 to 14.4.

Brighter asteroids:

(1) Ceres is in Sagittarius during September fading a little from magnitude 8.2 to 8.7 during the month. The dwarf planet will be slow moving in Sagittarius, being stationary on the 15th. It will then be about 3.5° from the M55 globular cluster.

(4) Vesta is in Cetus throughout September brightening from magnitude 6.7 to 6.3 during the month. The asteroid rises at 8.16 pm on the 1st. By the end of September it will rise about 40 minutes before sunset and set nearly an hour after sunrise.

(9) Metis is in Aquarius, starting the month at magnitude 9.2. It will then rise at the time of sunset but not set until well after sunrise. The asteroid is at opposition on September 6. By the end of the month it will have dimmed slightly to magnitude 9.6

(15) Eunomia starts September in Andromeda with a magnitude 8.4. It moves into Pegasus on the 22nd. Opposition is at the end of September when Eunomia will have brightened to 7.9. It will then be the second brightest asteroid in the sky. , having crossed into Pegasus on the 22nd.

(29) Amphitrite starts September at magnitude 9.9. It is in Aries and stationary on the 7th. By the 30th it will have brightened to magnitude 9.3 and be just under 5° from the star beta Ari.

Brian Loader  
New Zealand