APRIL 2018

As April begins, the Sun is in the constellation of Pisces, but crosses the border into Aries at around 23h00 the 18th.
The Moon
The Moon is at apogee, the furthest from the Earth, on April 20th at 14h00, and at perigee, its nearest to the Earth, at around 05h00 on the 8th.

Last Quarter Moon is at 07h18 on the 8th in Sagittarius.

April’s New Moon is on the 16th at 01h58, in the constellation of Pisces, passing south of the Sun

On the 22nd at 21h46 the Moon is at First Quarter, in Cancer and is one of the highest FQ moons of the year.

Full Moon is on the 30th at 00h59, and may be seen in Libra. The very bright star-like object 10° to the lower left of the Moon is Jupiter.

Look for Earthshine’s faint illumination of the night hemisphere at the time of the waxing crescent Moon on the 17th to the 21st, and the waning crescent from the 9th to the 15th. A final chance to see the evening cone of the Zodiacal Light occurs on fine evenings during the first half of April, although increasing twilight as the month progresses begins to interfere.
Its appearance is of a cone of pale light of less intensity than that of the Milky Way rising up from the western sky at an angle of 60° towards the south. It is caused by the sun back-lighting the disc of fine particles surrounding the Sun in the inner solar system; all that remains of the accretion disc which formed the planets 4.5 million years ago.

The Planets
Mercury is in inferior conjunction with the Sun on Easter Day, the 1st of April, whereafter it moves into the morning sky. However this is a very poor morning apparition of the planet and it will be difficult to see because of its low altitude and the brightness of Spring’s morning twilight. At no time during the month does it rise more than 40 minutes before the Sun.

Venus, as ‘Hesperus the Evening Star’ dominates the western sky after sunset and by the end of the month sets almost two and a half hours after the Sun. It cannot be mistaken as it is the brightest star-like object in the evening sky until it sets. It lies in the constellation of Aries and the young waxing crescent Moon may be seen approaching Venus on the evening of the 17th, at which time Venus lies 6° above the Moon. This will be a most beautiful sight, especially as Earthshine will enhance the Moon’s appearance.

Throughout April, Mars continues to increase in brightness, rising from +0.3 at the beginning of the month to -0.4 at the month’s end; not quite as bright as Sirius, but certainly brighter than Arcturus. On the 2nd, Mars lies just over 1° (two Moon widths) below Saturn. It is interesting to compare the colours of these two planets as at this time they are of similar brightness. Saturn is of magnitude +1.12, and so is slightly fainter than Mars. However, the colour contrast is very noticeable, Mars shining with an ochre colour and Saturn shining pale cream. The Red Planet rises just after 02h00 on the 1st, but by 01h30 on the 30th. It has become a very bright object in the morning sky in the constellation of Sagittarius, through which the planet moves eastwards. Unfortunately, Mars is very low in the SSE sky as the sky begins to brighten at the onset of dawn. The gibbous waning Moon may be seen near Saturn and Mars on the morning of the 7th, the two planets lying some 5° to the lower left of the Moon. Of academic interest, Mars passes 1.4° south of Pluto on the 26th.

Once Venus has set, Jupiter dominates the evening sky, rising at 22h as April begins, and shortly after sunset on May 1st. The planet lies in the constellation of Libra and far outshines the constellation’s brightest stars Zubenelgenubi and Zubeneschamali, with which Jupiter forms a triangle at this time. The waning gibbous Moon lies near to Jupiter on the evening of the 3rd, the Moon lying 5° to the right of the planet.
Opposition occurs on the 9th May, so this is an excellent time to look for the Galilean moons through well-focused and firmly fixed binoculars as they change position night by night.

Saturn rises shortly after 02h at the beginning of the month and soon after 00h (astronomical midnight) at the month’s end. As mentioned previously it lies in the vicinity of Mars in the constellation of Sagittarius, the two coming into conjunction on the 2nd, with the waning Moon close by on the 7th. The rings are still wide open and we continue to get a good view of their northern ‘surface’. Through a telescope, Titan, the largest of the Saturnian moons shining at magnitude +8, just a little dimmer than Neptune, may be seen at its greatest elongation west of Saturn on the 4th and 20th, and at its eastern elongation on the 12th and 26th. On the 16th it lies south of the planet, and on the 8th and 24th, Titan lies north of Saturn.

Uranus, in the constellation of Pisces, is in conjunction with the Sun on the 18th, and so is not favourably place for observation

Although Neptune, still in Aquarius, rises around 04h mid-month, it too is not favourably placed for observation at this time.

The Virginids, a weak meteor shower, with several radiants in the constellation of Virgo, producing some 5 slow-moving long-pathed meteors, occurs during late March to mid-April. The maximum of this stream is expected overnight on the 11th/12th.

Conditions are very favourable for the The Lyrids this year. This meteor shower peaks overnight on the 21st/22nd, when up to 10 meteors an hour may be seen radiating from the vicinity of the bright star Vega in the constellation of Lyra. The best time to look for them is during the two hours before dawn starts to brighten the sky in the early morning on the 22nd, and stray Lyrids may be seen for several days before and after this date.
The Lyrid meteor shower is associated with Thatcher’s Comet discovered in 1861.

Constellations visible in the south around midnight, mid-month, are as follows: The eastern part of Hydra, Corvus the Crow, Virgo, Boötes and Coma Berenices. The Plough, in the constellation of Ursa Major, is still near the zenith.
All times are GMT 1° is one finger width at arm’s length.

 APRIL EVENTS SUMMARY (Using Coelix Software)

The phenomena of the month : April 2018
Times are given in standard time for SCARBOROUGH (0° 25' 5" W, 54° 16' 30" N, zone UT).

Date Hour Description of the phenomenon
yyyy mm dd hh:mm

2018 04 01 00:00 EASTER DAY
2018 04 01 17:38 Maximum of the variable star eta Aquilae
2018 04 01 17:54 INFERIOR CONJUNCTION of Mercury with the Sun (geoc. dist. centre to centre = 2.8°)
2018 04 01 23:35 Close encounter between Mars and M 22 (topocentric dist. centre to centre = 0.4°)
2018 04 02 13:12 Close encounter between Mars and Saturn (topocentric dist. centre to centre = 1.3°)
2018 04 02 18:31 Maximum of the variable star delta Cephei
2018 04 03 08:04 Minimum of the variable star Algol (beta Persei)
2018 04 04 01:07 Beginning of occultation of 44-eta Lib (magn. = 5.41)
2018 04 04 02:13 End of occultation of 44-eta Lib (magn. = 5.41)
2018 04 06 04:53 Minimum of the variable star Algol (beta Persei)
2018 04 08 03:18 Maximum of the variable star delta Cephei
2018 04 08 03:25 End of occultation of 41-pi Sgr (magn. = 2.88)
2018 04 08 05:32 Moon at apogee (geocentric dist. = 404144 km)
2018 04 08 07:18 LAST QUARTER OF THE MOON
2018 04 08 12:41 Minimum of the variable star beta Lyrae
2018 04 08 21:53 Maximum of the variable star eta Aquilae
2018 04 09 01:42 Minimum of the variable star Algol (beta Persei)
2018 04 10 03:31 Maximum of the variable star zeta Gemini
2018 04 11 22:31 Minimum of the variable star Algol (beta Persei)
2018 04 13 12:05 Maximum of the variable star delta Cephei
2018 04 14 19:20 Minimum of the variable star Algol (beta Persei)
2018 04 16 01:57 NEW MOON
2018 04 16 02:06 Maximum of the variable star eta Aquilae
2018 04 17 16:09 Minimum of the variable star Algol (beta Persei)
2018 04 18 00:00 Saturn at its aphelion (distance to the Sun = 10.06568 AU)
2018 04 18 14:01 CONJUNCTION between Uranus and the Sun (geoc. dist. centre to centre = 0.5°)
2018 04 18 20:53 Maximum of the variable star delta Cephei
2018 04 20 07:08 Maximum of the variable star zeta Gemini
2018 04 20 08:03 Opposition of the asteroid 187 Lamberta with the Sun (dist. to the Sun = 2.073 AU; magn. = 10.1)
2018 04 20 12:58 Minimum of the variable star Algol (beta Persei)
2018 04 20 14:44 Moon at perigee (geocentric dist. = 368714 km)
2018 04 21 11:15 Minimum of the variable star beta Lyrae
2018 04 22 13:44 Meteor shower : Lyrids (18 meteors/hour at zenith; duration = 9.0 days)
2018 04 22 21:46 FIRST QUARTER OF THE MOON
2018 04 23 06:20 Maximum of the variable star eta Aquilae
2018 04 23 09:48 Minimum of the variable star Algol (beta Persei)
2018 04 23 11:00 Mercury at its aphelion (distance to the Sun = 0.46670 AU)
2018 04 24 05:40 Maximum of the variable star delta Cephei
2018 04 24 20:35 Close encounter between the Moon and Regulus (topocentric dist. centre to centre = 0.5°)
2018 04 26 06:02 Close encounter between Mars and Pluto (topocentric dist. centre to centre = 1.4°)
2018 04 26 06:37 Minimum of the variable star Algol (beta Persei)
2018 04 29 03:26 Minimum of the variable star Algol (beta Persei)
2018 04 29 14:27 Maximum of the variable star delta Cephei
2018 04 29 18:00 GREATEST WESTERN ELONGATION of Mercury (26.9°)
2018 04 30 00:58 FULL MOON
2018 04 30 10:33 Maximum of the variable star eta Aquilae
2018 04 30 10:45 Maximum of the variable star zeta Gemini