Night Sky Notes – July 2019

Night Sky notes for July 2019                         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. In July there are two highlights to observe, planet Saturn at opposition 9th July and the Partial Lunar Eclipse on July 16th.  Shortly after sunset on July 16th look low on the south eastern horizon to see the Full Moon rising in eclipse at 9.09pm with the top half covered by the Earth’s umbra shadow, mid eclipse occurs at 10:30pm when the Earth’s umbra shadow covers up to 65% of the Moon. The partial phase of the eclipse ends by midnight. Note the pale yellow appearance due to Moon passing through the Earth’s outer Penumbra shadow, the normal bright appearance of the Full Moon is restored by 01:19am on 17th July.

On the evening of Friday July 13th a local public open observing evening at Stopsley Common for telescopic observing of Jupiter, Saturn and The Moon is planned. Particular interest in the Moon this month with the 50th Anniversary of the Apollo 11 Moon Landings in July.  Luton Astronomical Society is supporting the Bradgers Hill s wildlife group event (Please refer to the home page for more information).

Jupiter shines brightly low in the south in the constellation of Ophiuchus, telescopes show the planets characteristic banding of the equatorial cloud belts and the four bright Galilean moons Io, Europa, Ganymede and Callisto changing position night to night. Larger telescopes show detail of the Great Red Spot a pale pink / straw coloured feature in the South Equatorial Belt – Current Interest is heightened by  the interaction of the feature with surrounding white ovals.  Below Jupiter and to the right find the blood red star Antares in Scorpius.

Saturn is found low in the southern aspect in the constellation of Sagittarius. This favours more southern observers as all the planets are low in UK skies. Saturn’s 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.

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 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 southern aspect late evening to find the distinctive `T` shaped asterism of stars of the `head` of Scorpius . Although rather low as seen from the UK, 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.

Planets in July 2019

Mercury heads into the daytime skies from early July with inferior conjunction on July 21st.

Venus is now located in our daytime skies and so is not visible this month.

Mars is now extremely low in evening twilight – not observable this month.

Jupiter is located low in the south and is past opposition, cloud belt and Galilean moons visible using a small telescope.

Saturn reaches  opposition on July 9th , low in the south in Sagittarius – 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.

Dwarf planet Pluto reaches opposition on July 14th near the Teaspoon asterism in Sagittarius,

Moons phases in July 2019

New Moon         July 2ndth              Moonless, best time for deep sky observing.

(Total solar eclipse visible from South America)

 

First Quarter     July 9th                 Best days to see shadow details in lunar craters (early evening)

Full Moon            July 16th              Best days to see bright ray craters like Copernicus / Tycho.

(Partial Lunar Eclipse visible from UK, moon rises in eclipse.)

 

Last Quarter      July 25th                Moon visible in daytime skies.  Do not look directly at the Sun.

Meteor shower s                             Southern δ Aquarids, maxima around 28th July, poor, moonlight interferes.

Capricornids, several maxima in July, bright yellow / blue meteors, low rates.

 

The highlights of the month.

Partial Lunar Eclipse, moon rising in eclipse July 16th ( see notes  )

Jupiter is low in the southern aspect – telescopes show the equatorial cloud belts and four Galilean moons.

Saturn is low in southern aspect; rings almost wide open at 26° DE [tilt] showing Saturn’s North Pole.

Scutum, Sagittarius and Scorpius are 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 www.lutonastrolink.org.uk

Waxing  crescent Moon visibility    . Caution.  Do NOT look at the Sun directly with or without optical aid.  A very thin, 1.4% waxing crescent Moon is visible after sunset from around 21:30 BST to moonset 22:10 BST on July 3rd   .  Only look for the crescent Moon after the sun has completely set.

Sky looking south at 11pm British Summer Time (BST), Late July 2018

In the south the ringed planet Saturn currently is located in Sagittarius, just above the Teapot asterism

Low In the south the constellation of Sagittarius (noted by the famous Teapot asterism) rises late evening. This area of sky is rich in star fields of the Milky Way and has many fine clusters but is only observable in our evening skies during the summer months. Looking  at Virgo we look outside our own Milky Way galaxy towards the external galaxies of the Virgo Cluster , look  to Sagittarius  to into the spiral arm of our own galaxy, the centre of our own galaxy is however too far south to see from the UK

To the west of Sagittarius is the constellation of Scorpius. From the UK we only see the head; the rest of the constellation is visible from more southerly locations. Catch a glimpse in July of the red star Antares (The rival of Mars) on the stem of the `T` asterism low in the south/ southwest.

Two planets, Jupiter and Saturn are visible low in our southern aspect in July. Saturn reaches opposition early in the month.

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.

 

 

Sky looking east at 11pm BST mid July 2019

In July, the summer constellations of Lyra and Cygnus are rising by mid evening, the Milky Way may be visible on moonless evenings from a dark site.  Stretching from low in the south east to low in the north west, this misty band is best seen with binoculars, follow the star fields from Altair, down through Scutum and into Sagittarius is stunning in a dark sky. If you are on holiday and visiting a dark sky site, remember to take a pair of binoculars with you.

Partial Lunar Eclipse (July 16th) – Use binoculars to give a good view of the lunar eclipse.

The partially eclipsed Moon rises about 9:15pm, mid eclipse 10:30pm (around 65% of the moon is covered by the Earth shadow (Umbra), the eclipse ends about midnight.

Simulated view of Moonrise on July 16th 2019 (Stellarium)

 

 

 

 

 

Sky looking north at 11 pm BST late July 2019

The Plough stands with its handle pointing upward follow the pointer’s Dubhe and Merek to find the polestar Polaris. The `W` shaped constellation of Cassiopeia is near to its lowest point in the north late evening.  The Milky Way follows the galactic equator and stretches from east through the constellations of Cygnus, Cassiopeia, Perseus and down into the northern horizon.  The bright star Capella is positioned almost due north and is circumpolar i.e. does not set from our latitude.

 

Sky looking west at 11 pm BST Late July 2019

Low in the west late evening the bright orange star Arcturus and the white star Spica can be found by following the handle of `The Plough` asterism in an extended arc .

More detailed finder charts and newsletters are available to LAS members on the member’s page.