Sky Notes June 2015

Sky Notes for June 2015                                   Geoff Mitchell

As we approach the summer solstice on June 21st observing is now limited to late evening. The June 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 west by early evening and joins Venus for a close planetary conjunction by 30th June. The brilliant planet Venus shining brightly setting some three hours after the Sun. Telescopes shows Venus has phases (like our Moon). Currently Venus is approaching 50% (Dichotomy) at greatest elongation on June 6th and then increasing in apparent size to 30 arc sec (38% phase ) by late June and reducing in phase to a thin crescent in July as the planet moves towards inferior conjunction in August.

The summer 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. Look to the NW around 2 hours after sunset or to the NE 2 hours 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 east the summer constellation of Cygnus [The Swan] now rises in evening twilight. The Milky Way can be seen as a faint band of stars stretching low in the east down through constellations of Aquila [The Eagle], Scutum [The Shield] and towards Sagittarius [The Archer] and Scorpius [The Scorpion] in midnight skies, 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. Sagittarius is best seen in June / July, the constellation is known for the `Teapot` asterism of stars has rich star fields and some fine star clusters located above the spout of the Teapot asterism; however you do need a good southern horizon and finder chart to spot some of these. Pluto is located just above `the handle of the teapot asterism` and it is a thought to note that NASA’s New Horizon space probe is due to flyby Pluto in the coming months . Similarly another Dwarf planet Ceres, a binocular object magnitude 7.8 located in the pre dawn constellation of Capricornus [The Sea Goat] currently has the NASA DAWN space probe orbiting it. Asteroid (No 2) Pallas is located in our late evening sky in the constellation of Hercules and reaches opposition on June 3rd, magnitude 8.9 m. Hercules is noted for the Globular cluster M13 containing some 750,000 stars, a nice view in a small telescope.
The bright star Vega in the 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.

Look low in the SE late evening to find a yellowish star and the distinctive `T` shaped asterism of stars of the `head` of Scorpius , the yellow star is in fact the ringed planet Saturn which reached opposition on May 23rd. 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. Look below the `T` head of Scorpius to see the `blood red`
coloured star Antares. Antares name means `The rival of Mars`, a red super giant star, with a mass of some 20 solar masses. It has a diameter that, on the scale of our solar system, would be greater than the orbit of Mars.

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 south the bright orange star Arcturus in the constellation of Bootes [The Herdsman] is the brightest star in the northern hemisphere of the sky.

Planets in June
Mercury returns low in the dawn skies reaching greatest elongation on June 24th.
Venus shines brightly and is positioned low in the west after sunset visible in evening twilight. Venus is positioned close to the open star cluster M44 (Beehive cluster) on June 13th
Mars is lost to daytime skies, reaching conjunction in mid June.
Jupiter is now in twilight, watch Jupiter and Venus close in late June and see the close conjunction on June 30th.
Saturn now rises by late evening in Scorpius low in SE evening skies- a good time to see this ringed `gem` .
Uranus is placed in our pre dawn skies – best views in autumn skies.
Neptune is placed in our pre dawn skies – best seen in autumn skies

Moons phases in June
New Moon June 16th Moonless, best time for deep sky observing.
First Quarter June 24th Best days to see shadow details in lunar craters (early evening) **
Full Moon June 2nd Best days to see bright ray craters like Copernicus / Tycho.
Last Quarter June 9th Moon visible in daytime skies. Do not look directly at the Sun.

Meteor showers Ophiuchids – weak meteor shower best for southern hemisphere observers

The Highlights of the Month
Venus dominates the evening twilight, showing characteristic phase (50%) greatest elongation (E) June 6th.

Jupiter and Venus closing to give a close planetary conjunction in the same telescopic [1°] field of view June 30th

Saturn low in south east, rings open at 24° DE [tilt] showing Saturn’s North Pole.

4 day old Moon, in evening twilight June 20th very low in NW with Regulus, Jupiter and Venus above

Beehive star cluster (M44) and Venus low in the evening twilight June 13th

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

More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website http://www.lutonastrolink.org.uk

Artificial satellite and International Space Station visible passes and bright Iridium flares – check the home page for postings of details of favourable observing times.

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