Night Sky Notes – May 2016

Night sky notes for May 2016                       Geoff Mitchell

The May night sky shows the summer constellations rising  mid evening and the spring constellations heading into the western twilight  The bright planet Jupiter is now low in the south by early evening and by late May  the Red Planet Mars  and the ringed planet Saturn can be seen late evening low in the southeast .

The late spring night sky contains many fine objects to view for the enthusiast in the midnight hours but also has a few notable events of special interest.   From late May onwards Look to the NW  some 90 minutes  after sunset  or to the NE 90 minutes  before sunrise  i.e. when the Sun just below the horizon during the summer months when extremely high clouds at 80 km altitude known as Noctilucent Cloud (NLC) may be seen. NLC’s show a bluish colour and also show filamentary structure.

The constellation of  Virgo due south as twilight fades contains a large cluster of Galaxies , the Virgo Super cluster , visible as faint misty patches in moderate sized telescopes – the bright late evening skies however makes observing these quite a challenge . Our own Milky Way galaxy stretches from the constellation of Auriga [The Charioteer], marked by the bright star Capella and through the constellations of Perseus and Cassiopeia all now positioned low in the north.  In the south the night sky looks outward to the distant galaxies of the Virgo and Coma cluster.

In the east the summer constellation of Cygnus [The Swan] now rises by late evening. The bright star Vega in the adjacent constellation of Lyra [The Lyre] is seen low above the north east horizon and Altair in the constellation of Aquila low in the east. Vega, Altair and Deneb, in the constellation of Cygnus form the `Summer Triangle` asterism, a useful sign post for the summer skies.  Adjacent to  Lyra the familiar `keystone asterism ` of the constellation  Hercules is noted for the Globular clusters  M13 and M92 the former containing some 750,000 stars, a nice view in a small telescope .

Scorpius [The Scorpion] in part is visible low in the south use binoculars to see the myriad of stars in these rich star clouds, best seen on clear dark moonless evenings from darker locations outside the town. The red star Antares, as the name means `rival to Mars ` currently this can be compared with the planet Mars also in Scorpius and shining brightly (magnitude -1.9m) at opposition (May 22nd ) and closest distance to Earth during this current opposition (0.5 AU .  71 Million km) May 30th. The low elevation of Mars as seen from the UK makes observing detail on Mars more difficult. Mars moves from Scorpius into Libra during the coming weeks as it moves retrograde against the background stars.

Look low in the SE late evening to find a yellowish star to the east of Mars. The yellow star is in fact the ringed planet Saturn which reaches opposition in early June in the constellation of Ophiuchus [The Serpent Bearer].  Although rather low as seen from the UK, its ring system is now 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.  Observe the Seeliger Effect from mid May to mid June around the date of opposition and note any brightening of the ring system due to the ring particles angle of illumination changing causing the apparent brightening.  Also in the constellation of Ophiuchus, periodic comet 252P / Linear is a fading binocular object rising by late evening low in the east.

The familiar asterism of the plough in the constellation of Ursa Major, The Great Bear is seen high overhead with its handle or tail pointing upwards 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.

High in the east the bright orange star Arcturus in the constellation of Bootes [The Herdsman] is the brightest star in the northern hemisphere of the sky.  Between Arcturus and the Keystone asterism in Hercules lies the `U` shaped constellation of Corona Borealis [Northern Crown] . At the time of writing one faint 11th magnitude star T Coronae Borealis ` Blaze Star` is reported to be in outburst, increasing in brightness at 9th magnitude but possibly may increase in a nova in the near future. This reoccurring nova is an eclipsing binary star that periodically sheds material and brightens to 2nd or 3rd magnitude; the last two outbursts were in 1866 and 1946.

On May 9th the planet Mercury transits across the Sun, refer to the LAS web site home page for details.  Do NOT look directly at the Sun with the eye or any form of optical aid; only use safe solar observing methods 


Planets in May 2016

Mercury is in the daytime skies (transit of Mercury May 9th), poorly placed in dawn skies by late May

Venus is in our daytime skies reaching Superior Conjunction on June 6th.

Mars is at opposition on May 22nd and rises late evening shining bright orange at magnitude -2m (See notes)

Jupiter is now in the south west by late evening, past opposition it is still a good view telescopically

Saturn now rises by late evening in Ophiuchus  low in SE – a good time to see this ringed `gem` .

Uranus is not visible in daytime skies – best views in autumn skies.

Neptune is not visible in daytime skies – best seen in autumn skies

Moons phases in May

New Moon         May 6th                 Moonless, best time for deep sky observing.

First Quarter     May 13th               Best days to see shadow details in lunar craters (early evening) **

Full Moon            May 21st              Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter      May 29th               Moon visible in daytime skies.  Do not look directly at the Sun.

Meteor showers:        Eta Aquarids – peak May 5th, range April 24th to May 20th – Favourable ZHR 40/ hour

The highlights of the month

Transit of Mercury – May 9th   Refer to LAS website home page and the SPA video on safe observing methods

Mars at opposition low in UK skies, rising late evening – unmistakable orange in colour and bright (-2m).

Saturn low in south east by late evening  , rings open at 26° DE [tilt] showing Saturn’s North Pole.

Comet 252P / LINEAR visible at 6th magnitude (Binocular) low in east late evening (See notes)

Reoccurring nova ` Blaze Star ` T Coronae Borealis in possible outburst?  (See notes)

Saturn, Mars and blood red star Antares make an easily recognised triangle in the late evening sky

Noctilucent cloud – from late May watch the NW skies 2 hours after sunset (see text)

Thin 1% waxing crescent Moon visible early evening on May 9th , note the dimly lit part visible by Earthshine.

More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website  Artificial satellite and International Space Station visible passes and bright Iridium flares – check the  home page for posting s of details of favourable observing times.