The Solar System In September 2016

Dates and times shown are NZST (UT + 12 hours) until the start of NZDT (UT + 13 hours) on Sunday 25 September at 2 am when clocks should be put forward 1 hour.

The southern spring equinox is on September 23 at 2:22 am.

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

Sunrise, sunset and twilight times in September

                            September  1  NZST               September 30  NZDT
                    morning  evening                 morning  evening
       SUN: rise:   6.43am,  set:  5.58pm    rise:   6.54am,  set:  7.27pm
  Civil:    starts: 6.18am,  ends: 6.24pm    starts: 6.29am,  ends: 7.53pm
  Nautical: starts: 5.46am,  ends: 6.56pm    starts: 5.56am,  ends: 8.26pm
  Astro:    starts: 5.14am,  ends: 7.28pm    starts: 5.23am,  ends: 9.00pm

September phases of the moon (times as shown by Guide)

          New moon:      September  1 at  9.03 pm (09:03 UT)
  First quarter: September  9 at 11.49 am (11:49 UT)
  Full moon:     September 17 at  7.05 am (Sep 16, 19:05 UT)
  Last quarter   September 23 at  9.56 pm (09:56 UT)

The planets in September 2016

Mercury, Venus and Jupiter start the month as a close group low to the west after sunset. Mercury will disappear after a few days and Jupiter after a few more days as they move into conjunction with the Sun.

Saturn and Mars remain prominent throughout the evening in the vicinity of Antares.

Mercury Venus and Jupiter

Mercury starts September as an evening object setting an hour and forty-five minutes after the Sun on the 1st. That evening, three-quarters of an hour after sunset, the planet at magnitude 1.4, will be almost due west and some 10° above the horizon. Finding it will be made easier by the presence of Venus 6.5° to its right and a little higher. Jupiter will also be present below Venus and slightly to its left.

Two evenings later the moon will join the group with the thin crescent of the two day old moon between Venus and Jupiter.

Over the next few nights Mercury will rapidly get lower in the evening sky to disappear in the twilight. On the 13th it is at inferior conjunction between the Earth prior to becoming a morning object. Towards the end of September, Mercury will rise about half an hour earlier than the Sun so remaining more or less unobservable.

Jupiter will also continue to get lower in the evening sky to be at conjunction on the far side of the Sun on the 26th. It will then be 5.45AU, 8.15 million km beyond the Sun.

Venus on the other hand will get a little higher in the evening sky, setting just over two and a half hours after the Sun on the 30th.

Mars and SATURN will also be in the evening sky forming a fairly close group with Antares at the beginning of the month. During September Mars will move away from Antares while the much slower moving Saturn will remain about 6° from the star.

Mars starts September in Scorpius, joins Saturn in Ophiuchus on the 3rd but moves on into Sagittarius on the 22nd. The moon, near first quarter, will join the two planets in Ophiuchus on September 9.

Outer Planets

Uranus, at magnitude 5.7, is in Pisces. By the end of September it will rise just over an hour after the Sun sets making it observable late evening.

Neptune is at opposition on September 2 when it will be 4330 million km, almost 29 astronomical units, from the Earth. The planet is in Aquarius at magnitude 7.8.

Pluto at magnitude 14.4 is also in the evening sky during September setting well after midnight. The planet remains in Sagittarius some 1.5° from the magnitude 2.9 star pi Sgr and less than half a degree from the magnitude 3.7 star omega Sgr.

Minor Planets

(1) Ceres is in Cetus during September and brightens from magnitude 8.4 to 7.8 making it the brightest asteroid. It is at its best as a morning object, although it will rise close to 10 pm on the 1st and close to 9 pm on the 30th.

(18) Melpomene is also in Cetus and close to Ceres, the two being less than a degree apart between September 6 and 10. Melpomene starts the month at magnitude 9.0 and ends it at 8.3, similar to Vesta.

(2) Pallas, in the evening sky, starts September at magnitude 9.3 in Equuleus. It moves into Aquarius on the 26th, dimming a little to 9.7 by the end of the month.

(4) Vesta rises close to 4 am on September 1, remaining in Gemini throughout the month. On the morning of the 3rd it will be only 10 arc-minutes from the 4th magnitude star zeta Gem. The asteroid brightens slightly during the month from magnitude 8.5 to 8.3. By the end of September it will rise about 3.40 am NZDT.

(11) Parthenope is another asteroid which brightens during September, from magnitude 9.8 to 9.2 when at opposition at the end of the month. It is also in Cetus although over 20° from Ceres and Melpomene.

Brian Loader  
New Zealand

The Solar System in August 2016

Dates and times shown are NZST (UT + 12 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 August

                            August  1  NZST                  August 31  NZST
                    morning  evening                 morning  evening
       SUN: rise:   7.26am,  set:  5.28pm    rise:   6.45am,  set:  5.57pm
  Civil:    starts: 6.59am,  ends: 5.56pm    starts: 6.20am,  ends: 6.23pm
  Nautical: starts: 6.26am,  ends: 6.29pm    starts: 5.48am,  ends: 6.55pm
  Astro:    starts: 5.53am,  ends: 7.01pm    starts: 5.16am,  ends: 7.27pm

August phases of the moon (times as shown by Guide)

          New moon:      August  3 at  8.45 am (Aug  2, 20:45 UT)
  First quarter: August 11 at  6.21 am (Aug 10, 18:21 UT)
  Full moon:     August 18 at  9.27 pm (09:27 UT)
  Last quarter   August 25 at  3.41 pm (03:41 UT)

The Planets in August

August is a month of planetary conjunctions. All the planets are visible at some time in the evening sky.

Mercury, Venus and Jupiter, early evening objects

Towards the end of August a fine grouping of the three planets will be visible in the early evening sky as the sky darkens following sunset. Between August 18 and 22 Mercury will be about 4° to the left of Jupiter. On the 18th Jupiter will be a little higher than Mercury. Over the next few evenings Jupiter will move down and become the lower of the two. Venus will be a few degrees below the pair.

Over the following evenings Venus will close in on Jupiter. On the 27th it will be 42 arc minutes below Jupiter, the following evening Venus is 19 minutes above Jupiter. Mercury, at magnitude 0.9 nearly 3 fainter than Jupiter will 5° to the left of the pair and a little higher.

At their closest just before midday, NZST, on the 28th, the two planets will be about 4 arc minutes apart. In NZ skies they are about 32° up at an azimuth of 52°, ie 52° from north round to east. In a clear sky Venus should be readily visible in binoculars or a small telescope. Having found Venus, Jupiter, about 2 magnitudes fainter, should be visible at least in a small telescope. The pair will be some 22° from the Sun.

On the 29th Venus is at its closest to Mercury. The two will be some 5° apart with Jupiter 1.3° below Venus. The line from Venus to Jupiter is almost at right angle to the line from Venus to Mercury.

The moon passes the three planets early in the month. For NZ it is closest to Venus on the evening of the 4th, when the very thin crescent moon, Venus and Regulus will form a triangle, just over 2° on each side. The moon is 3° above Mercury on the 5th and half a degree from Jupiter on the 6th. The moon occults both Mercury and Jupiter this month, but neither events are visible from NZ.

For good measure Venus is about a degree from Regulus, magnitude 1.4, on August 5 and 6.

Mars, Saturn and Antares

Not to be outdone, Mars and Saturn are also in conjunction towards the end of August. They are at their closest on the 24th, with Mars between Saturn and Antares. Mars, brightest at magnitude -0.4, will be 1.8° from Antares, mag 1.0, with Saturn, mag 0.4, in the opposite direction. The three will be easily seen all evening, they don't set until well after midnight.

Mars, moving quite rapidly, starts August in Libra but crosses into Scorpius on the 2nd. Its path takes it between delta and pi Sco (mags 2.3 and 2.9 respectively) on the 9th and 10th. As it passes between Saturn and Antares in the fourth week of August, Mars will cross a corner of Ophiuchus before returning to Scorpius on the 27th.

Saturn, in Ophiuchus, is stationary on the 13th so its position changes very little during the month.

The moon, a day after first quarter will join the group on the 12th. It is closer to Saturn, the two about 4.5° apart during the evening.

Outer planets

Uranus, at magnitude 5.8, is in Pisces. It rises nearly half an hour before midnight on August 1 and by 10 pm later in the month.

Neptune rises at 8am on the 1st and as the Sun sets on the 31st. (Opposition is on September 2). The planet is at magnitude 7.8.

Pluto at magnitude 14.3 is also in the evening sky during August setting well after midnight. The planet remains in Sagittarius. Late in the month it will be just under half a degree north of the 3.7 magnitude star Omega Sgr.

Minor planets

(1) Ceres is in Cetus during August and brightens from magnitude 8.9 to 8.4. It is essentially a morning object, although it will rise just after 10 pm on the 31st.

(2) Pallas starts August at magnitude 9.4 in Pegasus. It then rises at 8pm. Its retrograde motion takes Pallas into Equuleus on August 21 having been at opposition on August 13 at magnitude 9.2.

(4) Vesta rises close to 5 am on August 1. It is in then the most northerly part of Orion some 15° north of Betelgeuse. By the 7th it will have moved on into Gemini. At the end of August, Vesta will rise just before 4am. Its magnitude is 8.5 to 8.4.

(18) Melpomene starts August in Pisces at magnitude 9.6 it moves to the east into Cetus on the 16th. By the month it will have brightened to magnitude 9.0 and be less than 2° from Ceres when it will rise just after 10 pm

Brian Loader  
New Zealand