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« September 2015

The Night Sky October 2015

For September Night Sky click on link top left.

Compiled by Ian Morison

This page, updated monthly, will let you know some of the things that you can look out for in the night sky.  It lists the phases of the Moon, where you will see the naked-eye planets and describes some of the prominent constellations in the night sky during the month.

An Amateur's Guide to Observing and Imaging the Heavens

written by the author and aimed to bridge the gap between beginner's books on astronomy and the many specialised book on individual topics was published last year by Cambridge University Press.   If you look for it on Amazon Books you will find two excellent short reviews, one is by Stephen James O'Meara, one of the world's top visual observers, and one by Damian Peach, arguably the world's top planetary imager.

'A Journey through the Universe'

was also published by CUP last year giving an up to date review of what we know about our Universe.   Martin Rees has written a very nice review of it.

Image of the Month

Enhanced Colour Image of Pluto imaged by the New Horizons Spacecraft


Enhanced colour image of Pluto

Image: NASA, John Hopkins University/APL, Southwest Research Institute.

Colour data and images of Pluto taken by the New Horizons spacecraft during its flyby in July have been combined to give an enhanced view of an ancient world sporting an unexpectedly young surface.   The enhanced colurs make surface regions of different chemical composition visually distinct.   For example, the light coloured, heart shaped, Tombaugh Regio is clearly seen to be divisible into two regions that are geologically different.   New Horizons will soon be directed to change course so that it can fly past asteroid 2014 MU69 in January 2019.

Highlights of the Month

October - A good month to observe Uranus with a small telescope.

Uranus in Pisces
Image: Stellarium/IM

Uranus comes into opposition - when it is nearest the Earth - on the night of the 11th/12th of October, so will be seen well this month - particularly from around opposition when no moonlight will intrude.   Its magnitude is +5.9 so Uranus should be easily spotted in binoculars lying in the southern part of Pisces to the east of the Circlet asterism and east-southeast of 4th magnitude stars Epsilon Piscium and Delta Piscium as shown on the chart.   It rises to an elevation of ~45 degrees when due south.   Given a telescope of 4 inches it should be possible to see that it has a disk (3.6 arc seconds across) which has a pale green-blue tint.   With an 8 inch telescope and good seeing, perhaps using a green filter it may even be possible to see some detail in the planet's cloud features which appear to be more prominent than usual.   That is an observing challenge!   Four of its satellites, Arial(+14.4), Umbrial(+15), Titania (+13.9) and Oberon (+14.1) can also be seen given a night of good seeing and a telescope of 8 inches diameter or more.

October 3rd - 1 hour before sunrise: Venus, Mars and Jupiter arc across the sky

Three Planets
An arc of three planets
Image: Stellarium/IM

Before dawn on the 3rd of October and looking east one will, if clear, see the planets Venus (top), Mars (middle) and Jupiter (bottom) making an arc across the sky below the body of Leo.   Between Mars and Venus will be seen Regulus, Alpha Leonis.

October 8th, 9th and 10th - one hour before sunrise: the Moon joins the planets.

Crescent Moon
Planets and a thin crescent Moon.
Image: Stellarium/IM

The planets Venus, Mars and Jupiter will be joined by a thin crescent Moon in the eastern sky one hour before sunrise.   Jupiter is closing in on Mars and it might just be possible to spot Mercury lying just above the horizon if you have a very clear view in this direction.

October 11th - 30 minutes before sunrise: Mercury below a thin cresent Moon.

Mercury below a crescent Moon.
Image: Stellarium/IM

Before dawn on the 11th around 30 minutes before sunrise, and given clear skies and a low eastern horizon, you should be able to spot Mercury just two and a half degrees to the lower left of a very thin crescent Moon.

October 17th - 1 hour before sunrise: A conjunction of Jupiter and Mars.

A conjunction of mars and Jupiter
Image: Stellarium/IM

Before dawn, if clear, you should be able to spot Mars (shining at magnitude +1.7) just 24 arc minutes to the left of Jupiter (magnitude -1.8).   Venus, at magnitude -4.4, will then be lying 6 degrees to their upper right.

October 4th: Mons Piton and Cassini

Location of Mons Piton:IM

Mons Piton and the crater Cassini
Best seen just before Third Quarter, Mons Piton is an isolated lunar mountain located in the eastern part of Mare Imbrium, south-east of the crater Plato and west of the crater Cassini.   It has a diameter of 25 km and a height of 2.3 km.   Its height was determined by the length of the shadow it casts.  Cassini is a 57km crater that has been flooded with lava.   The crater floor has then been impacted many times and holds within its borders two significant craters, Cassini A, the larger and Cassini B.

Mons Piton
Mons Piton and Cassini

A Messier Object imaged with the Faulkes Telescope: M57 in Lyra

Ring Nebula, M57
The Ring Nebula, M57
Image:Danial Duggan
Faulkes Telescope North.

Planetary Nebula M82, imaged by Daniel Duggan.
This image was taken using the Faulkes Telescope North by Daniel Duggan - for some time a member of the Faulkes telescope team.   Lying at at distance of 2.3 thousand light years in the constellation Lyra, it is the remnant of a star like our Sun.   The core of the star has contracted down to an object about the size of the Earth supported by electron degeneracy pressure and is seen in the centre of the object.   The outer parts of the star were blasted out into space forming the "ring" (or torus) that we see.   Though showing very well in images, the central "star", called a "White Dwarf" is hard to see visually.

Learn more about the Faulkes Telescopes and how schools can use them: Faulkes Telescope"

Observe the International Space Station

The International Space Station
The International Space Station and Jules Verne passing behind the Lovell Telescope on April 1st 2008.
Image by Andrew Greenwood

Use the link below to find when the space station will be visible in the next few days. In general, the space station can be seen either in the hour or so before dawn or the hour or so after sunset - this is because it is dark and yet the Sun is not too far below the horizon so that it can light up the space station. As the orbit only just gets up the the latitude of the UK it will usually be seen to the south, and is only visible for a minute or so at each sighting. Note that as it is in low-earth orbit the sighting details vary quite considerably across the UK. The NASA website linked to below gives details for several cities in the UK. (Across the world too for foreign visitors to this web page.)

Note: I observed the ISS three times recently and was amazed as to how bright it has become.

Find details of sighting possibilities from your location from: Location Index

See where the space station is now: Current Position

The Moon

3rd Quarter Moon
The Moon at 3rd Quarter. Image, by Ian Morison, taken with a 150mm Maksutov-Newtonian and Canon G7.
Just below the crator Plato seen near the top of the image is the mountain "Mons Piton".   It casts a long shadow across the maria from which one can calculate its height - about 6800ft or 2250m.
new moon first quarter full moon last quarter
October 12th October 20th October 27th October 4th

Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images

A World Record Lunar Image

World record Lunar Image
The 9 day old Moon.

To mark International Year of Astronomy, a team of British astronomers have made the largest lunar image in history and gained a place in the Guinness Book of Records! The whole image comprises 87.4 megapixels with a Moon diameter of 9550 pixels. This allows details as small as 1km across to be discerned! The superb quality of the image is shown by the detail below of Plato and the Alpine Valley. Craterlets are seen on the floor of Plato and the rille along the centre of the Alpine valley is clearly visible. The image quality is staggering! The team of Damian Peach, Pete lawrence, Dave Tyler, Bruce Kingsley, Nick Smith, Nick Howes, Trevor Little, David Mason, Mark and Lee Irvine with technical support from Ninian Boyle captured the video sequences from which 288 individual mozaic panes were produced. These were then stitched together to form the lunar image.

Plato and the Alpine valley
Plato and the Alpine Valley.

Please follow the link to the Lunar World Record website and it would be really great if you could donate to Sir Patrick Moore's chosen charity to either download a full resolution image or purchase a print.

The Planets

 A montage of the Solar System
A montage of the Solar System. JPL / Nasa


A Cassini image of Jupiter . Nasa

Jupiter is one of the four pre-dawn planets that we can observe this month along with Mars, Venus and Mercury.   Shining at magnitude -1.7 (increasing to -1.8 during the month) it starts the month as the lowest of the three and will be just 12 degrees above the eastern horizon as dawn breaks.   It rises earlier as the month progresses moving upwards towards Regulus under the body of Leo, the lion, and will meet with Mars on the 17th of the month.   As the Earth moves towards Jupiter, the size of Jupiter's disk increases slightly from 31.4 to 33 arc seconds so early risers should be able to easily observe the equatorial bands in the atmosphere and the four Gallilean moons as they weave their way around it.

See highlights above.


The planet Saturn. Cassini - Nasa

Saturn.  At the start of October, Saturn, shining at magnitude +0.6, can be seen at an elevation of ~7 degrees low in the southwest about 45 minutes after sunset.   As the month progresses it will become increasingly hard to spot in the evening twilight.   It starts the month in eastern Libra setting around 2 hours after the Sun but passes into Scorpius on the 16th and is less than one degree above Beta Scorpii on the 26th of the month.   By month's end it sets one hour after the Sun.   Sadly, the atmosphere will seriously limit our view of its ~15 arc second disk and rings - now open ~24 degrees to the line of sight.   We will really have to wait for a few months until it can be seen in the pre-dawn sky.


Messenger image of Mercury Nasa

Mercury is also a pre-dawn object this month becoming visible (at magnitude +0.3) about the 11th close to a thin crescent Moon - but just 8 degrees above the horizon some 40 minutes before sunrise.   Binoculars may well be needed to spot it.   At this time Mercury will lie 20 degrees below Jupiter.   Mercury reaches greatest elongation west on the 16th but falls back towards the Sun brightening to magnitude -1 as it does so but becoming increasingly difficult to spot.

See highlight above.


Mars showing Syrtis major.
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa

Mars is a pre-dawen object starting the month almost halfway between Venus (above) and Jupiter (below) shining at magnitude +1.8 some 23 degrees above the eastern horizon an hour before sunrise.   On the mornings of the 17th and 18th, Mars, then at magnitude +1.7 is less than half a degree away from magnitude -1.8 Jupiter whose disk will appear almost exactly 8 time wider than Mars.   With Mar's disk still just 4 arc seconds across no details will be seen on its salmon-pink surface (unless, of course, you have access to the Hubble Telescope).

See highlights above.


Venus showing some cloud structure

Venus, shining initially at magnitude -4.7, will dominate the pre-dawn sky this month and will be some 30 degrees above the horizon as dawn breaks at the start of the month.   On the 26th of the month it reaches greatest elongation west some 46 degrees away in angular distance from the Sun.   It rises some four hours before the Sun though its disk may not appear half-lit until several days later.   Venus's apparent diameter shrinks from 33 to 23 arc second during the month but at the same time the percentage of its disk which is illuminated (its phase) increases from 35% to 53%.   As a result, the effective area reflecting the Sun's ligh remains almost constant which is why the magnitude only drops to -4.5 by month's end.

See highlights above.

Radar Image of Venus
Radar image showing surface features

Find more planetary images and details about the Solar System: The Solar System

The Stars

The Evening October Sky

October Sky
The October Sky in the south - mid evening

This map shows the constellations seen towards the south in mid evening. To the south in early evening - moving over to the west as the night progresses is the beautiful region of the Milky Way containing both Cygnus and Lyra. Below is Aquilla. The three bright stars Deneb (in Cygnus), Vega (in Lyra) and Altair (in Aquila) make up the "Summer Triangle". East of Cygnus is the great square of Pegasus - adjacent to Andromeda in which lies M31, the Andromeda Nebula. To the north lies "w" shaped Cassiopeia with Perseus below.

The constellations Lyra and Cygnus

Cygnus and Lyra
Lyra and Cygnus

This month the constellations Lyra and Cygnus are seen almost overhead as darkness falls with their bright stars Vega, in Lyra, and Deneb, in Cygnus, making up the "summer triangle" of bright stars with Altair in the constellation Aquila below. (see sky chart above)


Lyra is dominated by its brightest star Vega, the fifth brightest star in the sky. It is a blue-white star having a magnitude of 0.03, and lies 26 light years away. It weighs three times more than the Sun and is about 50 times brighter. It is thus burning up its nuclear fuel at a greater rate than the Sun and so will shine for a correspondingly shorter time. Vega is much younger than the Sun, perhaps only a few hundred million years old, and is surrounded by a cold,dark disc of dust in which an embryonic solar system is being formed!

There is a lovely double star called Epsilon Lyrae up and to the left of Vega. A pair of binoculars will show them up easily - you might even see them both with your unaided eye. In fact a telescope, provided the atmosphere is calm, shows that each of the two stars that you can see is a double star as well so it is called the double double!

The Double Double
Epsilon Lyra - The Double Double

Between Beta and Gamma Lyra lies a beautiful object called the Ring Nebula. It is the 57th object in the Messier Catalogue and so is also called M57. Such objects are called planetary nebulae as in a telescope they show a disc, rather like a planet. But in fact they are the remnants of stars, similar to our Sun, that have come to the end of their life and have blown off a shell of dust and gas around them. The Ring Nebula looks like a greenish smoke ring in a small telescope, but is not as impressive as it is shown in photographs in which you can also see the faint central "white dwarf" star which is the core of the original star which has collapsed down to about the size of the Earth. Still very hot this shines with a blue-white colour, but is cooling down and will eventually become dark and invisible - a "black dwarf"! Do click on the image below to see the large version - its wonderful!

M57 - The Ring Nebula
M57 - the Ring Nebula
Image: Hubble Space telescope

M56 is an 8th magnitude Globular Cluster visible in binoculars roughly half way between Alberio (the head of the Swan) and Gamma Lyrae. It is 33,000 light years away and has a diameter of about 60 light years. It was first seen by Charles Messier in 1779 and became the 56th entry into his catalogue.

M56 - Globular Cluster
M56 - Globular Cluster


Cygnus, the Swan, is sometimes called the "Northern Cross" as it has a distinctive cross shape, but we normally think of it as a flying Swan. Deneb,the arabic word for "tail", is a 1.3 magnitude star which marks the tail of the swan. It is nearly 2000 light years away and appears so bright only because it gives out around 80,000 times as much light as our Sun. In fact if Deneb where as close as the brightest star in the northern sky, Sirius, it would appear as brilliant as the half moon and the sky would never be really dark when it was above the horizon!

The star, Albireo, which marks the head of the Swan is much fainter, but a beautiful sight in a small telescope. This shows that Albireo is made of two stars, amber and blue-green, which provide a wonderful colour contrast. With magnitudes 3.1 and 5.1 they are regarded as the most beautiful double star that can be seen in the sky.

Alberio: Diagram showing the colours and relative brightnesses

Cygnus lies along the line of the Milky Way, the disk of our own Galaxy, and provides a wealth of stars and clusters to observe. Just to the left of the line joining Deneb and Sadr, the star at the centre of the outstretched wings, you may, under very clear dark skys, see a region which is darker than the surroundings. This is called the Cygnus Rift and is caused by the obscuration of light from distant stars by a lane of dust in our local spiral arm. the dust comes from elements such as carbon which have been built up in stars and ejected into space in explosions that give rise to objects such as the planetary nebula M57 described above.

There is a beautiful region of nebulosity up and to the left of Deneb which is visible with binoculars in a very dark and clear sky. Photographs show an outline that looks like North America - hence its name the North America Nebula. Just to its right is a less bright region that looks like a Pelican, with a long beak and dark eye, so not surprisingly this is called the Pelican Nebula. The photograph below shows them well.

The North American Nebula
The North American Nebula

Brocchi's Cluster An easy object to spot with binoculars in Gygnus is "Brocchi's Cluster", often called "The Coathanger",although it appears upside down in the sky! Follow down the neck of the swan to the star Alberio, then sweep down and to its lower left. You should easily spot it against the dark dust lane behind.

The Coathanger
Brocchi's Cluster - The Coathanger

The constellations Pegasus and Andromeda

Pegasus and Andromeda
Pegasus and Andromeda


The Square of Pegasus is in the south during the evening and forms the body of the winged horse. The square is marked by 4 stars of 2nd and 3rd magnitude, with the top left hand one actually forming part of the constellation Andromeda. The sides of the square are almost 15 degrees across, about the width of a clentched fist, but it contains few stars visibe to the naked eye. If you can see 5 then you know that the sky is both dark and transparent! Three stars drop down to the right of the bottom right hand corner of the square marked by Alpha Pegasi, Markab. A brighter star Epsilon Pegasi is then a little up to the right, at 2nd magnitude the brightest star in this part of the sky. A little further up and to the right is the Globular Cluster M15. It is just too faint to be seen with the naked eye, but binoculars show it clearly as a fuzzy patch of light just to the right of a 6th magnitude star.


The stars of Andromeda arc up and to the left of the top left star of the square, Sirra or Alpha Andromedae. The most dramatic object in this constellation is M31, the Andromeda Nebula. It is a great spiral galaxy, similar to, but somewhat larger than, our galaxy and lies about 2.5 million light years from us. It can be seen with the naked eye as a faint elliptical glow as long as the sky is reasonably clear and dark. Move up and to the left two stars from Sirra, these are Pi amd Mu Andromedae. Then move your view through a rightangle to the right of Mu by about one field of view of a pair of binoculars and you should be able to see it easily. M31 contains about twice as many stars as our own galaxy, the Milky Way, and together they are the two largest members of our own Local Group of about 3 dozen galaxies.

M 31 - The Andromeda Nebula
M31 - The Andromeda Nebula

M33 in Triangulum

If, using something like 8 by 40 binoculars, you have seen M31 as described above, it might well be worth searching for M33 in Triangulum. Triangulum is

the small faint constellation just below Andromeda. Start on M31, drop down to Mu Andromedae and keep on going in the same direction by the same distance as you have moved from M31 to Mu Andromedae. Under excellent seeing conditions (ie., very dark and clear skies) you should be able to see what looks like a little piece of tissue paper stuck on the sky or a faint cloud. It appears to have uniform brightness and shows no structure. The shape is irregular in outline - by no means oval in shape and covers an area about twice the size of the Moon. It is said that it is just visible to the unaided eye, so it the most distant object in the Universe that the eye can see. The distance is now thought to be 3.0 Million light years - just greater than that of M31.

M33 in triangulum - David Malin