The solar system in April 2016
NZDT ends on Sunday April 3 at 3am, clocks should then be set back one hour. Dates and times shown are NZDT (UT + 13 Hours) up to the change and then as 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 April
April 1 NZDT April 30 NZST morning evening morning evening SUN: rise: 7.34am, set: 7.14pm rise: 7.04am, set: 5.30pm Twilights Civil: starts: 7.09am, ends: 7.40pm starts: 6.38am, ends: 5.57pm Nautical: starts: 6.37am, ends: 8.12pm starts: 6.06am, ends: 6.30pm Astro: starts: 6.05am, ends: 8.44pm starts: 5.33am, ends: 7.02pm
April PHASES OF THE MOON (times as shown by GUIDE)
Last quarter: April 1 at 4.17 am (Mar 31, 15:17 UT) New moon: April 7 at 11.24 pm (11:24 UT) First quarter: April 14 at 3.59 pm (03:59 UT) Full moon: April 22 at 5.24 pm (05:24 UT) Last quarter April 30 at 3.29 pm (03:26 UT)
The planets in April
Jupiter will dominate the evening sky particularly early and late in the month when the moon is absent. Mercury is likely to be lost in evening twilight, setting soon after the Sun. Mars and Saturn will be to the east later in the evening, with Mars brightening to magnitude -1.5 during the month. Venus is rather low in the dawn sky.
Mercury is nominally in the evening sky in April but virtually unobservable. On the 1st it sets about 20 minutes later than the Sun, on the 30th about 26 minutes later. At its greatest, mid month, when the planet is at its greatest elongation 20 ° east of the Sun, it sets later.
Venus is a low object in the morning sky in April. On the 1st it will be about 16° up as the Sun rises just north of east. By the end of the month it will be only 8.5° at sunrise, so a low but not impossible object to spot shortly before the Sun appears.
Uranus will be less than a degree to the lower left of Venus on the morning of the 23rd, but with a magnitude of 5.9 it is very doubtful the fainter planet will be visible in binoculars in the twilight.
The moon, as a very thin crescent, will be 7° above Venus on the morning of the 6th, the following morning the moon will be a similar distance below Venus. As a hair line crescent, less than 1% lit, the moon will be very difficult to spot.
Mars brightens during April by a magnitude from -0.5 to -1.5 as its distance from the Earth decreases leading up to its opposition in May. The planet rises at 9.40 pm (NZDT) on the 1st and 6.40 pm (NZST) on the 30th so by then is visible most of the night.
The planet starts April in Scorpius, 6° from Antares. It crosses into Ophiuchus on the 3rd when it will be some 8.5° from Saturn. But on the 17th Mars is stationary and then starts moving back to the west to cross back into Scorpius on the last day of the month. As a result it remains quite close to the similarly coloured Antares all month.
The moon, just past full, is closest to Mars on the 25th, when Mars, Saturn and the moon will form a near equilateral triangle with Mars at the upper apex.
Jupiter, having been at opposition early March, will be a prominent evening object throughout April. It will be in Leo moving slowly to the west towards Regulus, with the star 15° to the left of the planet as seen in the evening sky.
The moon and Jupiter will be closest on June 18, when the 87% lit moon will be about 3° from Jupiter mid evening.
Saturn will rise about 10.15 pm on the 1st, advancing to 7.20 pm on the 30th. It will not set until after sunrise. The planet remains in Ophiuchus heading slowly to the west towards Mars. The two are closest mid month when about 7° apart.
As noted for Mars, the moon will form a triple with the two planets on the evening of the 25th. In fact the moon is closest to Saturn on the morning of the 26th with the two 4° apart shortly before sunrise.
Uranus is at conjunction on the far side of the Sun on April 9, so will not be observable during April. At conjunction Uranus will be 20 arc-minutes south of the Sun's limb. Distance wise it will be 20.0 AU from the Sun and 21 AU (3137 million km) from the Earth.
By the end of April Uranus will rise 90 minutes before the Sun and will be 8° above Venus. The two are closest on the morning of April 23.
Neptune, in the morning sky, starts April some 8° above and a little to the left of Venus. By the end of the month the two will be about 50° apart, due to the rapid motion of the inner planet. Neptune will then rise close to 2 am.
On the morning of April 5, Neptune will be 3.5° to the lower right of the crescent moon.
Pluto at magnitude 14.4 rises just after midnight at the beginning of April and about 9.35 pm on the 30th. The planet remains in Sagittarius. It is stationary on April 18 and is about 1° from the 2.9 magnitude star pi Sgr.
(1) Ceres, magnitude 9.2, starts April in Aquarius just under 7° to the right of Venus in the dawn sky. It crosses into Cetus on the 2nd where it soon falls behind Venus. This in fact means it gets steadily higher in the morning sky and will rise at 4 am by April 30.
(4) Vesta, magnitude 8.4, is in Aries until the 30th when it moves into Taurus. It sets 90 minutes after the Sun on the 1st, less than an hour later on the 30th.
The 5% lit crescent moon will be just over 1° to the right of Vesta on April 9. At 6.30 pm the two will be 8° above the horizon as seen from Wellington. Vesta will be about level with the upper lit cusp of the moon.
Brian Loader New Zealand