Sky Notes April 2015

Sky Notes for April 2015                                                       Geoff Mitchell

The April night sky now  shows the spring constellations but with daylight saving time (BST) and the Sun moving north of the celestial equator , twilight skies mean later observing hours as we head into the summer months.  The bright planet Jupiter is well placed high in the south by early evening.  The spring night sky contains many fine objects to view with both binocular and small telescopes and this month has a few notable events of special interest. The constellations of Leo and Virgo contain a large cluster of Galaxies , the Virgo Super cluster , visible as faint misty patches in moderate sized telescopes – Galaxy hunting season is now `open` . Our own Milky Way galaxy  stretches from the constellation of  Auriga , marked by the bright star Capella overhead  through the constellations of  Perseus  and Cassiopeia and down into the north west . This faint band of stars is best seen on clear dark moonless evenings from darker locations outside the town.

The familiar asterism of the plough in the constellation of Ursa Major, The Great Bear is seen high in the north east with its handle or tail pointing towards the horizon mid evening. Use the right hand pair of stars Dubhe and Merak (The pointers) to find the faint pole star Polaris and the position of North.

Look to the west early evening to see the brilliant planet Venus shining brightly. Telescopes shows Venus has phases (like our Moon). Over the coming months Venus phase reduces as it heads towards greatest elongation in June. Venus currently lies between the seven sisters’ (Pleiades, M45) star cluster and the Hyades star cluster which makes the characteristic `V` shaped asterism in the constellation of Taurus. The Moon passes close to the bright, red foreground star Aldebaren on April 21st. Aldebaren in Arabic Al Dabaran is `The follower ` of the Pleiades across the skies, in old English colloquially known as `the eye of the bull`.  By early evening the familiar winter constellations of Orion (The Hunter) and Taurus are now slipping into the western horizon.

Mercury makes an appearance low in the west after sunset later in April, with a conjunction with Mars on April 22nd. Mercury and Mars with a nice crescent Moon just below  is a challenge on April 19th . Mercury lies close to the Pleiades on April 30th as it heads towards greatest elongation on May 7th.

Jupiter moves from the constellation of Cancer (The Crab) towards Leo and the bright star Regulus and is past opposition but is still well placed for observing / imaging this month. Small telescopes show the four bright moons discovered by Galileo in 1610 and the famous cloud belts. The Great Red Spot is currently more subtle and straw coloured and has been fading recently.  Jupiter’s Galilean moons show shadow transits and go into eclipse behind the planet and with the current favourable orbital plane alignment which occurs every six years some moons can eclipse each other as seen from Earth.  A 21cm aperture or larger telescope is recommended to see the tiny dark shadow disks of the Galilean moons cast onto the cloud tops of Jupiter turbulent atmosphere.

The spring constellation of Leo rises by mid evening, the brightest star Regulus and the `reversed question mark ` shaped star asterism of `The Sickle` makes this an easily recognisable constellation. Leo stretches eastward and is marked at the tail end by the star Denebola.  Leo contains some moderately bright galaxy pairs visible in moderate sized telescopes on moonless evenings.  M65/M66 and NGC 3628 form the famous galaxy triplet, all three galaxies being visible in the same telescopic field of view.

The galaxy rich constellations of Virgo and Coma Berenices can now be seen rising by mid evening. The Virgo cluster of Galaxies has many relatively bright galaxies visible in moderate sized telescopes on moonless clear evenings.

Saturn positioned low in the constellation of Scorpius now rises by late evening in late April, reaching opposition in May. It is however rather low as seen from the UK, but has its ring system wide open, a classic view of this gem of the solar system. Small telescopes will show the rings and the brightest moon Titan. Larger telescopes show up to six or so fainter moons and any white oval features on the planets disk.

The bright star Vega in the constellation of Lyra is seen low above the northern horizon, rising high in the east by the early hours. Lyra is the radiant for the April Lyrids meteor shower, best seen in the early hours but with a rather low zenith hourly rate (ZHR) of just 18 meteors per hour. Lyra heralds the approach of summer skies.

Planets in April

Mercury is better placed low after sunset in our evening skies by the end of the month. Mars and Mercury are at close conjunction, just 1.25° apart on the evening of April 22nd

Venus shines brightly and is positioned low in south west after sunset visible in evening twilight.  Venus is positioned between the Seven Sister’s (Pleiades) and Hyades star clusters around April 10th

Mars is just visible very low in the west early evening in April.  Mars and the Moon are in close on April 19th

Jupiter shines brightly in the south on the border of Leo / Cancer (The Crab) early evening and is at now passed opposition but offers some good views in April (Public open evening planned for April 16th)

Saturn now rises by late evening during April and will be at opposition in May in our evening skies.

Uranus is placed in our daytime skies – best views in autumn skies.

 Neptune is placed in our daytime skies – best seen in autumn skies


Moons phases in April

New Moon         April 18th              Moonless, best time for deep sky observing.

First Quarter     April 25th             Best days to see shadow details in lunar craters (early evening)

Full Moon          April 4th                Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter      April 12th              Moon visible in daytime skies.  Do not look directly at the Sun.

Meteor showers                   April Lyrids, rather low rates, best in early morning April 18th to 25th.

The highlights of the month

Mercury and Mars conjunction April 22nd

April skies, Milky Way visible high overhead on moonless evenings in darker skies.

Jupiter dominates our evening skies, cloud belts and four of Jupiter’s moons visible in a small telescope.

Double cluster, on the Perseus /Cassiopeia border high overhead, nice pair of star clusters.

Pleiades (Seven Sister’s) star cluster (M45) and Venus low in the evening twilight good binocular view..

Beehive cluster (M44) visible to the unaided eye but best seen with binoculars.

Comet 2014 Q2 Lovejoy fades but remains telescopic in the constellation of Cepheus (see notes)

Telescopic triplet of galaxies M65/M66/NGC3628 in the constellation of Leo

Virgo cluster of Galaxies, brighter members of the cluster can be seen with small telescopes or binoculars.

International Dark Skies Week  – LAS Public Open Observatory evening  Thursday April 16th  see website  homepage for details.

More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website