Sky Notes for September 2015 Geoff Mitchell
The September night sky is perhaps offers some of the best observing conditions. With the autumn equinox for northern hemisphere observers on September 23rd the mix of summer and autumn contains many fine objects to view with both binocular and small telescopes. Also this month there is a Total Lunar Eclipse early morning of September 28th.
The constellations of Cygnus, Lyra and Aquila can be seen high overhead and into the south ; these are noted for the bright stars of Deneb, Vega and Altair respectively forming the `Summer Triangle ` asterism.
The Milky Way stretches from Perseus rising in the north east, through the `W` shaped constellation of Cassiopeia in the north east , along the cross shaped constellation of Cygnus. This faint band of stars best seen on moonless evenings continues down through the obscure constellation of Scutum and on in the direction of the centre of the Milky Way (not visible from the UK) low on the horizon.
In September, Mars and the red star Antares now appear very low in the south west early evening. Look at the faint band of light of the Milky Way stretching high overhead and low into the south. Use binoculars to reveal the rich star clouds that show a myriad of stars and some of the dark rifts, regions of the Milky Way spiral arm obscured by dust clouds on clear moonless evenings
Auriga has the bright star Capella and can be seen low in the north east early evening, Capella is circumpolar from UK latitudes and so is always visible. In the east the constellation of Pegasus, noted for its `Square ` shape and the adjacent constellation of Andromeda noted for The Andromeda Galaxy (M31) , visible to the unaided eye as a faint fuzzy patch on moonless evening can now be seen mid evening . The Square of Pegasus is a useful sign post constellation and also is a good test for sky conditions, (how many faint stars you see within the square is indicates just how good your seeing conditions are). Follow the two end stars (Scheat and Markab) down to find the star Fomalhaut in the constellation of Pisces Australis (The Southern Fishes), visible very low on the southern horizon late evening at the end of the month .
In the North West Ursa Major, The Plough or The Great Bear is seen low with its handle or tail parallel to the horizon late evening? Use the right hand pair of stars Dubhe and Merak (The pointers ) to find the faint pole star Polaris and hence the position of North . Follow the curve of Ursa Major’s tail to the orange star Arcturus in the constellation Bootes (The Herdsman) low in the west. To the east of Bootes find the `horse shoe ` shaped constellation of Corona Borealis (Northern Crown) and the `Keystone asterism ` in the constellation of Hercules also noted for the globular cluster M13 containing around 750,000 stars, a good view with modest telescopes.
Saturn is only just visible now low in the western twilight and is not well placed. However Uranus in the constellation of Pisces and Neptune in the constellation of Aquarius are now both evening objects that can be located using binoculars and a suitable finder chart. A good starting point is to locate the Square of Pegasus and the ring of stars below the Square known as the `Circlet` in the constellation of Pisces (The Fishes), then star hop using the finder chart. Uranus and Neptune are notable due to the blue and green colour, Telescopes show a tiny disc rather than the sharp pinpoints of stars in the field of view.
In the east mid evening the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus heralds the forthcoming autumn skies of a new observing season.
Harvest moon is at perigee (closest distance to Earth) at 03 hrs BST September 28th with Lunar Eclipse first contact 03:11 BST, mid eclipse (totality) 04:23 BST and last contact 05:27 – See the Moon turn copper red during totality a wonderful sight viewed with binoculars and a good subject for Astrophotographers .
The lunar eclipse will be visible from Europe and many parts of the world , so there may be images posted on web sites like www.spaceweather.com as well as the LAS web site – clear skies permitting.
Planets in September 2015
Mercury returns low in evening twilight during early September greatest elongation Sept 4th but the planet is poorly placed low in the west.
Venus shines brightly low in eastern skies at dawn but is not well placed in twilight.
Mars is just visible in the west early evening and is located close to the red star Antares in Scorpius.
Jupiter shines very low in the east in the constellation of Cancer (The Crab) pre dawn in September.
Saturn is poorly placed low in the west.
Uranus rises late evening in the constellation of Pisces. (Binocular / Telescope required).
Neptune in Aquarius rises early evening (Binocular / Telescope required). The constellation of Aquarius is positioned low in the south east by mid evening
Moons Phases in September
New Moon Sept 13th Moonless, best time for deep sky observing and Comets .
First Quarter Sept 21st Best days to see shadow details in lunar craters (early evening)
** Full Moon Sept 28th Best days to see bright ray craters like Copernicus / Tycho.
Last Quarter Sept 5th Moon visible in daytime skies. Do not look directly at the Sun.
** September Full Moon is also a `Perigee Moon ` , the Moon being near to its closest point in its orbit coincident with the Full Moon and the Total Lunar Eclipse of the Harvest Moon.
Equinox occurs on September 23rd at 23:45 BST
Piscids, range September to October, maxima September 9th and 21st – rather low rates.
The Highlights of the Month .
September skies, Milky Way visible high over head on moonless evenings in darker skies
**Look at the Moon illusion effect at moonrise around Full Moon September 27th and the Total Lunar Eclipse in the early hours of September 28th – Totality , mid eclipse 04:23 BST (03:11 BST to 05:27 BST)
Uranus and Neptune, binocular objects to find using suitable finder charts
M31 the Andromeda Galaxy is visible on moonless evenings, best seen in binoculars.
Double cluster, on the Perseus /Cassiopeia border, nice pair of star clusters
Albireo, the star Beta Cygnii is a nice blue/ yellow double star seen telescopically
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