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The Night Sky October 2009

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.

Image of the Month


First-light CMB Image from the Planck Spacecraft
Image: European Space Agency and Axel Mellinger

The Planck Mission has captured its first image of the early universe from its position 1.5 million kilometers outwards from the Sun from Earth.   Now in its stable solar orbiting position it will survey the Cosmic Microwave Background - the radiation left over from the Big Bang - that tells us how the universe was just 400,000 years after its origin.   Planck was lauched on May 14th and was ready to make its "first-light" survey from August 13 to the 27th.  All receiver systems, two of which were built at Jodrell bank Observatory, are performing perfectly and are giving data of higher resolution and sensitivity than ever before.  

The data from the first-light survey has been superimposed on an all sky image of the galaxy photographed by Axel Mellinger, showing a strip of data. Over the next 15 months Planck will make two independant surveys of the whole sky.  The mission promises to provide a wealth of data that will keep astrophysicists and cosmologists busy for many years!


Comparison images between Plank and WMAP
Image: NASA, European Space Agency/Ian Morison

These images are from an identical segment of the WMAP and Planck images. The top image is that made by the WMAP spacecraft and the bottom is from the first light Planck image of a region above and to the left of the galactic centre.   The centre image has been made by the author by overlaying the two images with a transparency of 50%.   The dark area in this image is where there is no Planck data.   The fact that the bright area looks "clean" and the colours are still well saturated shows a very high degree of agreement between the two images - though you will see that (as expected) the Planck image has a significantly higher resolution.   This will allow it to extend the CMB power spectrum to higher spatial frequencies that will give insights into both "inflation" and the relative amounts of normal and non-baryonic (dark) matter in the Universe.

Highlights of the Month

Around new Moon ~18th October: Find Uranus.

Chart showing position of Uranus
Image: Stellarium/IM

Uranus was at opposition on September 17th and is still well placed to observe in the late evening.  With a magnitude of +5.7 it lies just below the circlet of Pisces which itself lies below the square of Pegasus.   The chart show its position mid month as it moves down and to the right towards the star Beta Aquari.   Under very dark skies it would just be visible to the unaided eye, but binoculars will probably be need to see it from our light polluted skies.  

October 10th: A nice line up of the planets in the pre-dawn sky

Venus, Saturn and Mercury line up in the pre-dawn sky.
Image: Stellarium/IM

Around the 10th of October the three planets, Venus, Saturn ad Mercury lie close together in the early morning sky.   By the 16th, they have seperated somewhat bur are joined by the the waning crescent Moon.   If clear, this should make a wonderful skyscape. .

Find M31 - The Andromeda Galaxy

How to find M31
Image: Stellarium/IM

In the late evening, the galaxy M31 in Andromeda is visible in the south-east. The chart provides two ways of finding it:

1) Find the square of Pegasus. Start at the top left star of the square - Alpha Andromedae - and move two stars to the left and up a bit. Then turn 90 degrees to the right, move up to one reasonably bright star and continue a similar distance in the same direction. You should easily spot M31 with binoculars and, if there is a dark sky, you can even see it with your unaided eye. The photons that are falling on your retina left Andromeda well over two million years ago!

2) You can also find M31 by following the "arrow" made by the three rightmost bright stars of Cassiopeia down to the lower right as shown on the chart. Good Hunting!

Early evening 7th October: A gibbous Moon passes below the Pleiades cluster

Moon and M45
Moon and the Pleiades cluster
Image: Stellarium

In the early evening of October 7th, an 85% illuminated waning gibbous will be seen to pass below the Pleiades Cluster, low in the east-north eastern sky.   A nice scene to photograph!

October 16th: See an eclipse of Europa by Ganymede

An eclipe of Jupiter's moon Europa by Ganymede
Image Stellarium/IM

At the present time, the plane of Jupiter's equator and satellites is aligned with the Earth. This means that, at times, one of them will be seen to pass in front of another.   In October, there are two nice events: on the 10th of October at 9:44 pm BST there is an eclipse of Europa by Io and, as shown in the chart, on the 16th October Ganymede will eclipse Europa at 10:10 BST.

Around October 21st: the Orionid Meteor Shower

October 21st - around 1- 2 am
Image: Stellarium/im

Though the Orionids are not one of the most spectaculer showers with peak rates around 20 per hour, they are interesting as it is believed that the meteors originate from Comet Halley.   It is worth looking out for them for a week around the 21st as the shower is long lived.   They will best be seen in the hours before dawn when Orion is high in the southern sky.  The star chart shows where they appear to radiate from - called the radiant - at the upper left of Orion, close to the boarder with Gemini.   Its best to look almost vertically where the sky is most transparent.  Pleasingly, the Moon is not long after new, so its light will not interfere.   The Halley meteors are amongst the fastest and enter the upper atmosphere at ~41 km per hour and often leave what are called persistant trains - streaks of ionized gas as the incoming dust particles burn up in the atmosphere.   Halley's Comet actually gives us two meteor showers per year as we intersect its orbit twice as the Earth orbits the Sun.   The other is in May and the shower is called the Eta Aquarid shower.

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 18th October 26th October 4th October 11th

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.

Please follow the link to go to the 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.

Plato and the Alpine valley
Plato and the Alpine Valley.

The Lunar World Record 2009: Lunar World Record

The Planets

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


A Cassini image of Jupiter . Nasa

Jupiter, now lying in Capricornus, is easily visible in the evening sky and is seen in the south-east after twilight. During October, its magnitude drops very slightly; from -2.6 to -2.5.   It has an angular size of 45 arc seconds at the beginning of the month so a small telescope will show much detail on the surface if seeing conditions are good. Sadly, at the present time, Jupiter is close to the lowest part of the ecliptic and never reaches more than ~23 degrees above the horizon even when it will be seen due south, so highest in the sky (at ~20:00 UT in the middle of the month).   On the 26th, Jupiter will lie around 4 degrees below and to the right of a 67% illuminated Moon 2, days after first quarter.   One problem with observing Jupiter with a telescope when it is so low in the sky is refraction in the atmosphere. This shifts the different colours of light in Jupiters image by differing amounts, so giving a blurred image. Using a green filter will help considerably in giving a cleaner image and I have even used a very narrow band OIII filter to observe Jupiter in monochromatic light giving excellent results - but needing a relatively large telescope to collect sufficient light.

See also highlight above


The planet Saturn. Cassini - Nasa

Saturn reappears in the pre-dawn sky during October and will be best seen at months end when, at magnitude +1.1, it will rise at about 04:00 UT, some three hours before the Sun.   The ring system is still almost edge on to us and so will appear pencil-thin - the reason why Saturn is not a bright as it is when the rings are more open.   A small telescope will easily show its brightest satellite, Titan, and one of 8 or more inches aperture several more.

See also highlight above


Messinger image of Mercury Nasa

Mercury: reaches western elongation (when it is at its greatest angular distance from the Sun before dawn) on October 6th.   This is Mercury's most favourable dawn apparition this year as the ecliptic is aligned at a reasonable angle to the horizon in the autumn and so, as the Sun rises, Mercury will be 15 degrees above the horizon - in company with Venus and Saturn!   It will have reached 10 degrees elevation in the east south-east by the start of twilight so do try to spot it.

See also highlight above


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

Mars is becoming more prominent in the morning sky rising at about 22:30 UT in the middle of the month.  It starts the month in the constellation of Gemini but moves into Cancer on the 12th October.  Its magnitude increases slowly from +0.7 to +0.8 whilst its angular size slowly increases from 6.8. arc seconds.  It will be due south, so highest in the sky at ~06:30 UT in mid month.  Under ideal seeing conditions, a telescope might begin to show some of the more prominent features such as Syrtis Major.  We will have to wait a month or so until it will be seen more easily as the nights get longer and it rises earlier in the night!  The Earth will, of course, be overtaking Mars "on the inside track" so we will come closer to it and its angular size will increase so allowing more features on the surface to be seen.


Venus showing some cloud structure

Venus is now drawing closer to the Sun and can be seen low in the east rising a couple of hours before sunrise.  It will be close to the thin crescent Moon on the 16th October. It is now on the far side of the Sun from us so its angular size is only ~10 arc seconds.   Its phase increases from 90 to 95% during the month, but it will become increasingly lost in the Sun's glare.  Its magnitude remains at -3.8 during the month.  An interesting fact about its brightness is that it stays pretty constant at about -4 for most of the time that it is visible even though the apparent phase changes greatly.  When the phase is thin, Venus is nearer to us, when near full much further away so its angular size is far less.   As a result, the effective reflecting area of Venus as seen from Earth remains pretty constant.

See also highlight 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