Night Sky notes for July 2016 Geoff Mitchell
The summer solstice (June 21st) has now passed; the Earth reaches Aphelion (furthest point of its orbit around the Sun on July 4th at a distance of 152 million km (95 million miles) and the evening twilight noticeably fades earlier throughout the month. The July night sky shows the summer constellations prominently in the south east from late evening and the late spring constellations disappear into the western twilight. The bright planet Jupiter is now low in the evening twilight, Jupiter set less than two hours after the Sun by month end.- It is a thought that the NASA Juno spacecraft is due to reach Jupiter this month . Venus begins its slow return to evening twilight skies over the coming months. A close conjunction of Venus and Mercury on July 16th may be visible briefly, low in west in evening twilight [Only look for Venus once the Sun has set]. Mars shines brightly just past its recent perihelic opposition low in the south in the constellation Libra, with Saturn to the east in the constellation of Scorpius. This favours more southern observers as all the planets are low in UK skies. On the evening of Sunday July 17th a local public open planet observing evening is planned as part of the Bradgers Hill s weekend events (refer to the home page for more information) .
The summer night sky contains many fine objects to view for the enthusiast in the late evening hours but also has a few notable events of special interest. Look to the NW from around 90 minutes to 120 minutes after sunset or similarly to the NE hours before sunrise, when the Sun just below the horizon during the summer months . In the right conditions 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.
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 east the summer constellation of Cygnus [The Swan] now seen as evening twilight fades. 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 late evening 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 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 ( see notes ) to spot some of these. Dwarf planet Pluto is located just above `the handle of the teapot asterism`.
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. 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.
Current Astronomical News
Too far south for UK observers a 12th magnitude (telescopic) nova in the constellation of Scorpius has recently been reported. Also Comet C/2013 X1 (Panstarrs), located to the south of Scorpius although not visible from UK latitudes, is currently reported at 6.5m (binocular) in dawn skies from the tropics.
Planets in July 2016
Mercury returns low in the evening twilight from early July but is poorly placed Mercury and Venus are just 0.5° separation at conjunction on July 16th may be visible 30 min after sunset.
Venus is positioned low in the west after sunset visible in evening twilight.
Mars is now positioned in low in the south as twilight fades. Now past opposition Mars continues to shrink in apparent diameter as the distance from Earth increases. Now in the Martian summer season, some dust storm observations are reported in the Elysium region of Mars.
Jupiter heads into the evening twilight and is past its best for observation, cloud belt and Galilean moons visible using a small telescope.
Saturn now just past opposition, low in the south in Scorpius – a good time to see this ringed `gem`.
Uranus is placed in our– best views in autumn skies.
Neptune is placed in our midnight skies – best views in autumn skies.
Moons phases in July 2016
New Moon July 4th Moonless, best time for deep sky observing.
First Quarter July 12th Best days to see shadow details in lunar craters (early evening)
Full Moon July 19th Best days to see bright ray craters like Copernicus / Tycho.
Last Quarter July 26th Moon visible in daytime skies. Do not look directly at the Sun.
Meteor shower s Southern δ Aquarids, maxima around 28th July, favourable ZHR 20 / hour
Capricornids, several maxima in July, bright yellow / blue meteors, low rates.
The highlights of the month.
Mercury and Venus close together very low in the west in the evening twilight July 16th/17th look 30 minutes after sunset – you will need a good western horizon to see these two. Venus is better seen later in the year.
Mars shines brightly low in the south as twilight fades, unmistakably orange in colour.
Saturn low in south, rings wide open at 28° DE [tilt] showing Saturn’s North Pole.
Scutum, Sagittarius and Scorpius visible low in the south as twilight fades. Good star fields seen on moonless evenings. Also note the deep red colour of star Antares ` the rival of Mars` in Scorpius and globular cluster M4
Noctilucent cloud – watch the NW skies from 90 to 120 minutes after sunset to see these electric blue clouds.
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 posting s of details of favourable observing times.
Waxing crescent Moon visibility . Caution. Do NOT look at the Sun directly with or without optical aid.
A very thin, 2.6% waxing crescent 1½ day old moon is visible after sunset from around 21.30 to moonset 21.47
BST on July 5th. Note the dimly lit part visible by Earthshine is readily seen with binoculars or small telescope. Only look for the crescent Moon after the sun has completely set.