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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
Twilights
  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

The Solar System in July 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 July

                            July  1  NZST                    July 31  NZST
                    morning  evening                 morning  evening
       SUN: rise:   7.44am,  set:  5.04pm    rise:   7.27am,  set:  5.27pm
Twilights
  Civil:    starts: 7.16am,  ends: 5.33pm    starts: 7.00am,  ends: 5.55pm
  Nautical: starts: 6.42am,  ends: 6.08pm    starts: 6.27am,  ends: 6.28pm
  Astro:    starts: 6.08am,  ends: 6.41pm    starts: 5.54am,  ends: 7.01pm

July phases of the Moon (times as shown by GUIDE)

          New moon:      July  4 at 11.01 pm (11:01 UT)
  First quarter: July 12 at 12.52 pm (00:52 UT)
  Full moon:     July 20 at 10.57 am (July 19, 22:57 UT)
  Last quarter   July 27 at 11.00 am (July 26, 23:00 UT)

The planets in July

All five naked eye planets are visible during some part of the evening by late July. Mercury becomes easily visible in the early evening sky towards the end of the month. Venus will be lower Mercury from the second part of July. Mars remains prominent although fading a little while Jupiter gets lower to the east. Saturn will not be far from Mars.

Mercury is at superior conjunction on July 7, when it will be 47 million km (0.314 AU) beyond the Sun and 199 million km (1.33 AU) from the Earth. Before conjunction Mercury will be too close to the Sun to observe, after conjunction it becomes an evening object setting after the Sun. By the end of July the planet will set nearly 2 hours later than the Sun. On the evenings of the 30th and 31st Mercury will be less than a degree from Regulus with Mercury at magnitude -0.1, 1.5 magnitudes brighter than Regulus. About an hour after sunset the two will be 7° up in a direction half way between west and northwest.

Earlier in July on the 16th, Mercury and Venus will be less than a degree apart. But the two planets will set only 45 minutes after the Sun, making observation difficult. At 5.30 with the Sun only 4° below the horizon, the planets will be a low 4° above it. Venus at magnitude -3.9 May be detectable, Mercury's magnitude being-1.1.

Venus, in the very early evening sky will set less than half an hour after the Sun on the 1st and about 50 minutes after the Sun on the 31st. So it will be a very low object at best.

Venus starts the month in Gemini, moves across Cancer between July 10 and 26 and ends the month in Leo heading towards Regulus.

Mars remains a prominent evening object although loses a little of its brightness during July as the Earth recedes from it. By the end of the month it will still be bright at magnitude -0.8.

The planet will be in Libra moving rather slowly to the east after being stationary at the end of June. By the end of July, Mars will be poised to cross into Scorpius, heading towards its rival Antares.

The moon passes Mars mid month, but the two do not get very close. They are about 10° apart on the nights of July 14 and 15.

Jupiter becomes an early evening object during July, setting just after 9pm on the 31st. It remains in Leo.

The 25% lit crescent moon will be just over 1° from Jupiter on July 9. An occultation of the planet is only visible from the Southern Ocean to the south of Australia and parts of Antarctica beyond.

Saturn is well paced for evening viewing during July, a bright object about 6° from Antares which it will outshine by nearly a magnitude. The colour of the two makes a contrast. The planet is in Ophiuchus moving slowly in a retrograde sense to the west.

The 87% lit moon will be just under 4° from Saturn on the evening of July 16.

Outer planets

Uranus, at magnitude 5.9, is a morning object in Pisces although it will rise just before midnight by the end of July. It is stationary on the 30th , with its position changing only slightly during the month.

Neptune rises near 10 pm at the beginning of the month advancing to 8am by the month's end. The planet, at magnitude 7.9, is in Aquarius and will be about half a degree from the 3.7 magnitude star lambda Aqr. In the mid to late evening Neptune will be to the right of the star early in the month gradually moving up to be at the star's upper right by the end of the month. There are no stars as bright as Neptune between them to cause confusion.

Pluto at magnitude 14.3 is also in evening sky during July. The planet remains in Sagittarius. It moves away from the 2.9 magnitude star pi Sgr during July, starting only 8 arc-minutes from the star on the 1st, the distance increasing to almost a degree by the 31st.

Minor planets

(1) Ceres, is in Cetus during July moving to the east. It brightens slightly through the month, from 9.2 to 8.9.. It rises at 1.30 am on the 1st and close to midnight on the 31st.

(4) Vesta rises 100 minutes before the Sun on July 1 and just after 5 am on the 31st. Starting the month in Taurus, Vesta will be less than half a degree from the magnitude 3 star zeta Tau on the morning of the 14th. On the 21st the asteroid will cross into Orion.

Brian Loader  
New Zealand