THE SOLAR SYSTEM IN APRIL 2017
NZ reverts to NZST (UT +12 hours) on April 2 at 3am. Consequently dates and times shown are NZST apart for any on April 1.
SUNRISE, SUNSET and TWILIGHT TIMES in April
Times are for Wellington. They will vary by a few minutes elsewhere in NZ.
April 1 NZDT April 30 NZST
morning evening morning evening
SUN: rise: 7.33am, set: 7.15pm rise: 7.04am, set: 5.31pm
Twilights
Civil: starts: 7.09am, ends: 7.40pm starts: 6.38am, ends: 5.58pm
Nautical: starts: 6.37am, ends: 8.12pm starts: 6.05am, ends: 6.30pm
Astro: starts: 6.04am, ends: 8.44pm starts: 5.33am, ends: 7.02pm
APRIL PHASES OF THE MOON (times NZST, as shown by GUIDE)
First quarter: April 4 at 6.40 am (Apr 3, 6:40 UT)
Full moon: April 11 at 6.08 pm (06:08 UT)
Last quarter April 19 at 4.07 pm (04:07 UT)
New moon: April 27 at 12.16 am (Apr 26, 12:16 UT)
THE PLANETS in APRIL 2017
Jupiter becomes visible all night so is a brilliant object in the evening sky. Saturn will be to the east by late evening. Mars will be low to the west after sunset setting before the end of astronomical twilight. Venus moves up in the morning sky during April, a brilliant object to the east. Mercury is too close to the Sun to observe all month.
MERCURY is virtually unobservable throughout April. It is at inferior conjunction between Earth and Sun at 5pm on the 20th. At conjunction the planet will pass 1.5° north of the Sun as "seen" from the Earth. Mercury will be 86 million km from the Earth and 64.4 million km from the Sun.
On the 1st Mercury, in the evening sky, will set only 30 minutes after the Sun. On the 30th, in the morning sky, it rises about 80 minutes before the Sun but at magnitude 2.6 is not likely to be visible due to twilight.
VENUS is a morning object in April. On the 1st it will rise some 45 minutes before the Sun, by the 30th it will rise more than 3 hours earlier than the Sun.
The planet will not be readily visible on April 1 when it is only 12° from the Sun. Its distance from the Sun increases steadily throughout April, particularly early in the month as Venus moves to the west through the stars, away from the easterly moving Sun. This will make it an easy object within a few days. It will be visible a little to the north of east at first shortly before sunrise.
Venus is in Pisces all month and is stationary on April 13 after which it will start moving to the east but less rapidly than the Sun. The position of the planet relative to the stars will change little during the month
The morning of the 24th will find the crescent moon some 4.5° to the upper right of Venus
MARS will remain a low early evening object during April. On the 1st it sets just over 80 minutes after the Sun, dropping only slightly to 75 minutes later on the 30th. It will be low, with a magnitude 1.5, visible only briefly as the sky darkens following sunset. Mars will set a little before the end of Astronomical twilight so not be an easy object.
During April, the planet moves to the east through Aries and on into Taurus on the 12th. On the 21st and 22nd it will be 3.5° above the Pleiades, by the end of April Mars will be 7° below the similarly coloured star Aldebaran. On the 28th the moon, a very thin crescent less than 5% lit, will be 5° to the upper left of Mars.
JUPITER is at opposition on April 8, NZ time. At opposition Jupiter will be 4.5 AU, 666 million km from the Earth and a further 150 million km from the Sun. The planet will be in Virgo moving in a retrograde sense to the west as the Earth overtakes it. Jupiter starts the month just over 6° from Spica, its slow westerly motion taking it to nearly 9.5° from the star on the 30th.
The full moon will be 6.5° from Jupiter on the evening of April 11, the moon at the apex of an inverted triangle formed by it, Jupiter and Spica.
SATURN will rise close to 11 pm NZDT 1st of April, which becomes 10pm NZST on the 3rd with the time of rise advancing to just after 8 pm by the 30th. Thus it becomes a prominent later evening object to the east at magnitude 0.3 to the east during the month. It will, of course, be readily visible in the morning sky. By the end of April Saturn will be highest and due north about 3.40 am.
Saturn is stationary on the 6th, after which it will start moving to the west, but its position in Sagittarius will change little throughout the month.
The 75% lit waning moon will be 3.5° to the lower right of Saturn on the morning of April 17, with the two closest at about 6 am.
OUTER PLANETS
URANUS is at conjunction with the Sun on April 14. Hence it will be too close to the Sun to observe throughout April.
NEPTUNE, in the morning sky, rises about two and a half hours before the Sun on the 1st and nearly 5 hours earlier on the 30th. The planet is in Aquarius at magnitude 8.
PLUTO, magnitude 14.4, is in the morning sky rising about 12.40 am, NZDT, on the 1st and 9.45 pm on the 30th. It will remain in Sagittarius just under 2.5° from the 2.9 magnitude star pi Sgr.
MINOR PLANETS
(1) CERES is an early evening object, brightening slightly from magnitude 9.1 to 8.9 during the month. It is quite close to Mars moving on a path almost parallel to the major planet which overtakes Ceres during the month. On the 1st they are 4° apart with Ceres above Mars. On the 8th they are at their closest, 3° apart. By the 30th Ceres is will be dropping behind Mars, the two then being 5° apart.
On the 12th both Ceres and Mars move from Aries to Taurus, with Ceres crossing the border shortly before Mars.
(4) VESTA, an evening object in April, is in Gemini. It passes Pollux, magnitude 1.2, early in April, the two being closest on April 7, just over 2° apart. The asteroid moves on into Cancer on the 24th. Vesta dims slightly during the month from magnitude 7.7 to 8.0. It sets about 12.45 am, NZDT, on the 1st and just before 10.30 pm, NZST, on the 30th.
Brian Loader