The Night Sky October 2012
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
Our best view of the asteroid Vesta
NASA,JPL-Caltech,UCLA.The Dawn spacecraft has just ended a year long mission to the asteroid Vesta and the science team has produced this composite image. Its ancient surface shows the resulting cratering and troughs produced by impacts in the past. With a diameter of 500 km its low surface gravity allows for high cliffs and a mountain that is twice the height of Mt Everest. Vesta is the second most massive object in the asteroid belt after Ceres - which Dawn should reach in 2015.
Highlights of the Month
October 3rd: Venus exceedingly close to Regulus in Leo
Before dawn on the 3rd Venus will lie in Leo, just a few arcminutes below Regulus, Alpha Leonis. The closest approach is at 8 am and, with a driven mount and telescope, it ought to be possible to follow them into daylight. As they near on the preceeding two days the colour difference between them will be enhanced with the blue of Regulus contrasting the touch of yellow of Venus. The eye will, in principle, be able to just separate them at their closest approach, but their combined brightness may make them appear as one particularly as Venus will be ~150 times brighter than Regulus - it will be interesting to see!
October 4th to 7th: Comet C/2011 F1 passes close to the globular cluster M5
This month the comet c/2011 F1 (LINEAR), at magnitude 10, lies in the constellation Serpens and passes within a couple of degrees of the globular cluster M5 - meaning that it should be relatively easy to find. Serpens lies low in the west over to the left of the bright stars Arcturus as shown in the first image.   The detailed plot shows its location through the month but the best time to observe it is around the 4th to the 8th when it lies within 2 degrees up and to the left of the 5.7 magnitude globular cluster M5. With a short focal length refractor and a 2" low power eyepiece both should be visible in the same field of view. You might even see a short tail extending from the comet's coma out to the left.
October 7th: Chi 2 Orionis occulted by the Moon
The +4.6 magnitude star Chi 2 Orionis will be occulted by the Moon in the early hours of the 7th of October. The waning, 21 day onld Moon will be high in the south-east in the contellation Orion. The reappearance from behind the dark limb occurs at about 3:45 am dependant on your location in the UK. (3:46 BST in London, 3:40 in Edinburgh.)
October around 9pm: Spot Brochi's Cluster and the double star Albireo in Cygnus.
October 8th: The Draconid meteor shower
On the night of October 8th the Earth will cross the orbit of the comet Giacobini-Zinner. If its clear, get to a location with a good north-western horizon as darkness falls! The radiant of the shower is, as their name implies, in the constellation Draco, the dragon, which will be at a reasonable elevation in the north-west during the evening. Its probably best to look above the radiant towards Cassiopeia as meteors are best seen at an angle of 45-60 degrees away from it. The Moon, at 3rd quarter, is rising in the East, so should not prove a problem in seeing the fainter meteors.
Find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum
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.
Around new Moon (15th Oct) you may also be able to spot M33, the third largest galaxy after M31 and our own galaxy in our Local Group of galaxies. It is a face on spiral and its surface brightness is pretty low so a dark, transparent sky will be needed to spot it using binoculars (8x40 or, preferably, 10x50). Follow the two stars back from M31 and continue in the same direction sweeping slowly as you go. It looks like a piece of tissue paper stuck on the sky just a bit brighter than the sky background. Good Hunting!
October 18th: Mars near a thin crescent Moon
About one hour after sunset on the 18th, if clear and given a good low western horizon, it should be possible to spot Mars below and to the right of a thin crescent Moon. Not far off, down to the left of Mars is the reddish star Antares on Scorpius. The three will make a nice and colourful grouping. See also if you can see the dark part of the Moon's surface illuminated by reflected light from the Earth (Earthshine). NB: The sky brightness in this image has been reduced from what you might expect to see - binoculars might be needed.
Around October 21st: the Orionid Meteor Shower
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. 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. The Moon at first quarter will be setting in the west so should not cause a problem. 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.
October 6th: Mons Piton and Cassini
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.
A Messier Object imaged with the Faulkes Telescope: M57 in Lyra
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 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 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 15th||October 22nd||October 29th||October 8th|
Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images
A World Record Lunar Image
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 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.
Jupiter rises around 10 pm at the beginning of October and by 8 pm by month's end but will be best seen before dawn some 60 degrees above the horizon in the constellation of Taurus, the Bull. Shining at magnitude -2.5 it starts October lying just ~8 degrees to the upper left of the star Aldebaran, the eye of the Bull. Jupiter has now started its retrograde motion so whilst its magnitude increases to -2.7 it will end the month slightly closer to Aldebaran as it begins to move above the Hyades cluster. Jupiter ends it retrograde motion in the middle of February and then moves eastwards towards the horns so, for several months, it will remain close to the cluster. Over the month its angular diameter increases from 43 to 47 arc seconds so even a small telescope will show plenty of detail with the bright zones and darker bands crossing the disk and up to four Gallilean moons visible.
Saturn passes behind the Sun on the 25th of October so will only be seen just a few degrees above the west south-west horizon about half an hour after sunset during the first week of the month. Binoculars will probably be needed to spot the magnitude +0.7 planet.
Mercury, reaches greatest elongation from the Sun on October the 26th - which is usually the best time to observe it. However, this autumn, it lies well below the ecliptic which make a shallow angle to the horizon at this time of the year so it will only be about 3 degrees above the south-west horizon half an hour after sunset. Binoculars will almost certainly be needed to spot it shining at magnitude -0.1, but I am not convinced that it would be worth the effort.
Mars, moving eastwards from Libra into Scorpius on the 6th, is visible low in the west after sunset whilst its rapid eastwards motion through the heavens keeps it visible throughout the month. It starts the month in Libra shining at magnitude +1.2. This remains constant during the month whilst its angular diameter falls from 4.8 to 4.6 arc seconds so it is unlikly that any surface marking could be seen on its salmon-pink disk. On the 1st of the month, its elevation is will be about 12 degrees as darkness falls some 45 minutes after sunset. On October 10th/11th Mars passes just 2 degrees below the (13.5 arc second separation) double star Beta Scorpii - the uppermost star forming the "tail" of the scorpion. In fact, each of the "two stars" is made up of 3 components so it is actually composed of 6 stars. A telescope should be able to separate one of the pair into two with a separation of 3.9 arc seconds.
See highlight above.
Venus. rises about 3.5 hours before the Sun this month and, with a magnitude close to -4.1 dominates the pre-dawn sky. For the first week of the month it lies within 5 degrees of Regulus in Leo passing it very closely on the 3rd as it moves eastwards entering Virgo on the 23rd. During October, its angular size drops from 16 to 13 arc seconds but, at the same time, the percentage illumination increases from 71 to 80% so the brightness hardly changes - from -4.1 to -4.0 magnitudes.
See highlight above.
Find more planetary images and details about the Solar System: The Solar System
The Evening October Sky
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
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!
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!
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.
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.
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.
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 constellations 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.
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.