Night sky notes for April 2018 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 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 bright planet Jupiter is rises low in the east by late evening. The bright planet Venus is visible in the western twilight below the Seven Sisters star cluster (M45) by late April , setting some two hours after the Sun.
Galaxy hunting season is now `open` the constellations of Leo and Virgo contain a number of Galaxies. The brighter member galaxies of the Virgo Super cluster, are visible as small, faint misty patches in moderate sized telescopes on moonless clear evenings from a dark observing site. Use the star Vindemiatrix as a starting point, to view the chain of brighter galaxies including M87 which are visible as tiny `smudges`.
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 ( Use the pointers) to find the faint pole star Polaris and the position of North.
The spring constellation of Leo rises early 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.
Jupiter currently in the constellation of Libra reaches opposition in early May but is low in the east as seen from the UK , 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 galaxy rich constellations of Virgo and Coma Berenices can now be seen rising by mid evening and well placed due south by late evening . Some of the brighter galaxies may be seen as faint misty patches telescopically. Markarian’s chain of galaxies stretching from the bright star Vindemiatrix towards the star Denebola in Leo, contains the brighter galaxies M59, M60, M86 and M87 (See notes).
Saturn positioned low in the constellation of Sagittarius now rises in the early hours in late April, but will be an evening object at opposition in early June. 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 red planet Mars is also located in the constellation of Sagittarius and so rises in the early hours during April. Mars will be low in UK skies at opposition late July in our evening skies.
Low in the north east 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.
Comet 2016 R2 Panstarrs now heads towards perihelion in May and is a faint telescopic (11.5 magnitude) object located in the constellation of Auriga during the month of April.
Planets in April 2018
Mercury is at inferior conjunction on April 1st, greatest elongation April 29th (dawn) – poorly placed in UK skies.
Venus is well placed in the dusk skies, setting some two hours after the Sun. Visible low in the west, early evening.
Mars is visible low in the east early morning in April showing a small (10 arc second) disk telescopically
Jupiter shines brightly low in the east in Libra late evening reaching opposition in May see www.lutonastrolink.org.uk for details of forthcoming observing evenings)
Saturn now rises by after midnight during April but will be at opposition in early June 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 16th Moonless, best time for deep sky observing and comet observing.
First Quarter April 22nd Best days to see shadow details in lunar craters (early evening)
Full Moon April 30th Best days to see bright ray craters like Copernicus / Tycho.
Last Quarter April 8th Moon visible in daytime skies. Do not look directly at the Sun.
Meteor shower s April Lyrids, rather low rates, best in early morning April 18th to 25th.
The highlights of the month.
Venus in twilight evening skies during April – Venus and the Pleiades star cluster – late April .
April skies, Milky Way visible high overhead on moonless evenings in darker skies.
Jupiter returns to our late 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 Hyades cluster in Taurus
Beehive cluster (M44) visible to the unaided eye but best seen with binoculars.
Comet 41P close approach April 1st (see notes) visible in binoculars / telescope in dark skies
Comet 2015 V2 (Johnson), binocular / telescopic in Hercules low in the east late evening (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 2018 – Refer to LAS website home page for details.
4.1% waxing crescent Moon is visible low in the west after sunset , Earthshine faintly illuminates (April 17th 9pm).
More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website www.lutonastrolink.org.uk
Sky looking south at 10pm British Summer Time (BST), mid April 2018
Gemini is placed high in the south west with Castor leading Pollux across the sky. To the south the constellation of Leo noted by the bright star Regulus and the `Sickle` asterism of stars and outstretched body resembles a crouching lion , with the star Denebola at the tail end. Between Pollux and Regulus, binoculars show the nice `Beehive` star cluster in the constellation of Cancer.
Telescopes show galaxies such as the three edge on spiral M65, M66 and NGC 3628 the famous Leo Triplet.
The Virgo cluster has many faint galaxies , the brightest member galaxies can be seen as faint `smudges` using binoculars from a dark observing site on clear moonless evenings.
Sky looking east at 10pm BST mid April 2018
The spring constellations now appear in the eastern sky by mid evening. The orange star Arcturus is found by following the curve of stars in the handle of the Plough down. The constellation of Bootes, resembles a `kite` or `Club ` in shape. The star Izar is a beautiful orange/ blue double star visible in small telescopes. To the east of Bootes find the `horseshoe` shaped constellation of Corona Borealis (Northern Crown) and the `Keystone` Asterism in the constellation of Hercules. Hercules also has M13 the famous Globular Cluster, visible to the unaided eye as a misty patch; telescopes show the true wonder of this cluster with over 750,000 stars. Likewise another nice globular is M92 in Hercules.
The bright white star Spica in the constellation of Virgo is easily found. Virgo has the super cluster of Galaxies, some of the brighter member galaxies can be seen as misty patches or ovals using modest telescopes . Finder charts see notes, more detailed finder charts are available on the LAS Member’s page (LAS Newsletter No 144) .
Jupiter is now visible from late evening in late April
Sky looking north at 10pm BST mid April 2018
The Plough stands on its handle follow the pointer’s Dubhe and Merek to find the polestar Polaris
The `W` shaped constellation of Cassiopeia is found on the opposite side of the polestar to the Plough. Low in the northeast the bright star Vega in the constellation of Lyra skirts the horizon, rising by early morning. Lyra is associated with the radiant of the April Lyrids meteor shower. Rates of these meteors, derived from Comet C/1861 Thatcher are rather low, range April 16th to 25th.
Sky looking west at 10pm BST mid April 2018
Venus shines brightly low in the west , setting some two hours after the Sun
Highlights of the month
Virgo cluster of Galaxies. located in `the bowl ` of Virgo between bright stars Vindemiatrix in Virgo and Denebola in Leo , the brightest member galaxies shown are bright enough to see as faint misty patches with a small telescope or binoculars . Virgo is a `Y` shaped constellation with the bright white star Spica at the base.