The Night Sky July 2013
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
NGC 6302, the Butterfly Nebula
Image: NASA, ESA and the Hubble SM4 ERO Team
NGC 6302, the Butterfly Nebula, is one of the most beautiful planetary nebulae in the heavens. These are the remnants of stars like our own as they end their lives is a massive explosion ejecting much of the stars material into space and leaving an earth sized object, a "white dwarf star", which is the dying ember of the star's core at a temperature of ~250,000 degrees Celsius. NGC 6302 lies about 4,000 light-years away in the constellation Scorpius. Its central star is hidden from view by a dense taurus of dust, but its ultra violet light is exciting hydrogen to emit light at the pink-red H-alpha spectral line.
Highlights of the Month
Early July: A very good time to spot Noctilucent Clouds!
Noctilucent clouds, also known as polar mesospheric clouds, are most commonly seen in the deep twilight towards the north from our latitude. They are the highest clouds in the atmosphere at heights of around 80 km or 50 miles. Normally too faint to be seen, they are visible when illuminated by sunlight from below the northern horizon whilst the lower parts of the atmosphere are in shadow. They are not fully understood and are increaing in frequencey, brightness and extent; some think that this might be due to climate change! So on a clear dark night as light is draining from the north western sky long after sunset take a look towards the north and you might just spot them!
July - Find the globular cluster in Hercules and spot the "Double-double" in Lyra
There are two very nice objects to spot with binoculars in the western sky well after dark this month. Two thirds of the way up the right hand side of the 4 stars that make up the "keystone" in the constellation Hercules is M13, the best globular cluster visible in the northern sky. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name! More details can be found within the "Astronomical A-List" (Link is at upper left.)
July - Use a telescope to view two of the best planetary nebula in the northern sky - The Ring and Dumbell Nebulae in Lyra and Vulpecular respectivly.
When it finally gets dark during July the beautiful region of the sky including Cygnus, Lyra and Aquilla will be high in the south-east. The constellations brightest stars: Vega in Lyra, Deneb in Cygnus and Altair in Aquila making up what is called the summer triangle. Within this region lie two of the brightest planetary nebulae that we can observe in the northern skies. Between Beta and Gamma Lyrae, the pair of bright stars lying below Vega, is the Ring Nebula, M57, seen as a tiny "smoke ring" in a small telescope whilst, below Cygnus in Vulpecula is the Dumbell Nebula, M27. M27 can even be seen with 10 x 50 binoculars given a dark, transparent, sky. Details of both these beautiful objects can be found within the "Astronomical A List" section of our website (link at upper left) or within the author's book "Pocket Guide to Stars and Galaxies" for which the list was initially produced.
July 3rd after sunset - Venus lies within the Beehive cluster in Cancer
About 30 or so minutes after sunset on the 3rd of July and given a low western horizon you should be able to spot Venus lying in front of the Beehive Cluster, M44, in Cancer. Binoculars will probably be needed to pick Venus out against the twilight sky and it may be possible to pick out some of the brighter stars of the cluster. Using higher powers with a telescope will reduce the apparent sky brightness and should allow the cluster stars to be more easily seen. Note: the sky brightness has been reduced in the image.
July 6th before dawn - Mars, Jupiter and a thin crescent Moon
Before dawn on the 6th of July, a thin crescent Moon will join Mars and Jupiter low above the horizon in the East-Northeast. Binoculars will probably be needed to spot Jupiter but please do not use them after the Sun has risen. Note: the sky brightness has been reduced in the image.
July 12th after sunset - A thin crescent Moon joins Venus in the twilight sky below Regulus in Leo.
About 30 or so minutes after sunset around the 12th of July and given a low western horizon you may be able to spot the Moon and Venus lying below the constellation Leo with its brightest star Regulus above and between them. Note: the sky brightness has been reduced in the image.
July 22nd before dawn - Mars and Jupiter under a degree apart.
Before dawn on the 22nd of July, Mars and Jupiter will lie just 47 arc minutes apart making a very close grouping. They remain very close the following morning.
July 22nd after sunset - Venus comes within one and a quarter degrees of Regulus in Leo.
About 45 minutes after sunset on the 22nd of July you may, if clear, be able to spot Venus very close to Regulus low above the western horizon
July 24th after sunset - A line-up of Saturn's moons
As twilight darkens after sunset on the 24th of July it would, if clear, be well worth using a telescope to observe Saturn. That evening the brighter of its moons form a nice line-up in the sky from Iapetus well down to the left of Saturn up to Dione just above. A good imaging opportunity!
July 17th and 18th: Two Great Lunar Craters
Two great Lunar Craters: Tycho and Copernicus
This is a great night to observe two of the greatest craters on the Moon, Tycho and Copernicus, as the terminator is nearby. Tycho is towards the bottom of Moon in a densely cratered area called the Southern Lunar Highlands. It is a relatively young crater which is about 108 million years old. It is interesting in that it is thought to have been formed by the impact of one of the remnents of an asteroid that gave rise to the asteroid Baptistina. Another asteroid originating from the same breakup may well have caused the Chicxulub crater 65 million years ago. It has a diameter of 85 km and is nearly 5 km deep. At full Moon - seen in the image below - the rays of material that were ejected when it was formed can be see arcing across the surface. Copernicus is about 800 million years old and lies in the eastern Oceanus Procellarum beyond the end of the Apennine Mountains. It is 93 km wide and nearly 4 km deep and is a clasic "terraced" crater. Both can be seen with binoculars.
A Messier Object imaged with the Faulkes Telescope: NGC 1365
Galaxy NGC 1365, imaged by Nik Szymanek.
This image was taken using the Faulkes Telescope by Nik Szymanek - one of the UK's leading astro-photograpers. NGC1365 is also known as the Great Barred Spiral Galaxy and lies at a distance of 56 million light years. It is one of the most perfect barred spirals with a straight bar and two very prominent spiral arms. Closer to the centre there is also a second spiral structure. The galaxy is an excellent "laboratory" for astronomers to study how galaxies form and evolve.
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|
|July 8th||July 16th||July 22th||July 29th|
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, passed behind the Sun on the 19th of June and so, in July, re-emerges into the pre-dawn sky shining at magnitude -1.9 with a disk ~32 arc seconds across. Binoculars will almost certainly be needed to spot it but please cease using them when the Sun rises. On the 6th of July it might just be possible to spot Jupiter down to the lower left of a thin crescent Moon and the planet Mars. During the month it will gradually rise sooner than the Sun making it easier to spot and move closer to Mars when, on the 22nd July they are only 0.8 degrees apart. By month's end Jupiter rises some two hours before the Sun lying between the feet of the heavenly twins, Gemini.
See highlight above.
Saturn, lying in Virgo, is now several months past opposition so will be seen in the south west after sunset. It lies 11 degrees to the left of Spica, Alpha Virginis and will appear slightly brighter with a yellowish hue. Saturn's magnitude falls during the month, from +0.5 to +0.6 magnitudes, whilst its angular size decreases from 17.6 to 17.1 arc seconds. It begins the month just just 0.5 degreees away from the the magnitude +4.2 star, Kappa Virginis. Saturn has just ended its retrogarde motion across the sky and so remains virtually stationary half way between the the stars Spica and Alpha Librae. The rings have now opened out to ~17 degrees from the line of sight and we are now observing the planet's southern hemisphere whilst much of the northern hemisphere will be hidden by the rings. With a small scope one should now be able to spot Cassini's Division within the rings if the "seeing" is good along with Saturn's largest Moon, Titan. Saturn is now lying in the more southerly part of the ecliptic so its elevation does not get that high when seen from our northern latitudes and, sadly, this will get worse for quite a number of years.
See highlight above.
Mars will lie about 7 degrees above the north-eastern horizon half an hour before sunrise as July begins and should be visible in binoculars in the pre-dawn sky - but please cease using them at sunrise! It begins the month with a magnitude of +1.5 which increases very slightly to magnitude +1.6 by month's end. On the morning of the 6th it will lie between the horns of Taurus some 6 degrees to the left of a thin crescent Moon. By the end of July, Mars will rise some 2 hours before the Sun having moved eastwards into Gemini on the 14th of the month. From the 20th to the 24th of July it passes just above Jupiter being only 0.8 degrees distant on the morning of the 22nd.
See highlight above.
Mercury passes between the Earth and the Sun on July 9th (inferior conjunction)and will only become visible in the pre-dawn sky during the last week of the month. However, it brightens rapidly as it comes to greatest western elongation from the Sun on the 29th of July reaching almost zeroth magnitude. On the previous morning, it will lie 7 degrees below Mars.
Venus. As July begins, Venus is 25 degrees east of the Sun at Sunset, but as the plane of the ecliptic is at a shallow angle to the horizon at this time of the year, it will only be 11 degrees above the horizon. Given a really low western horizon at the end of twiligt it will have an elevation of just 5 degrees, but given its magnitude of -3.9 it should be easily visible. During the evening of July 3rd, Venus is within the Beehive star cluster (M44 in Cancer) and the stars, though far fainter might be visible with binoculars at around 10:30 pm. On the 22nd July, it passes just one degree north of Regulus shining at magnitude +1.3 in Leo.
See highlight above.
Find more planetary images and details about the Solar System: The Solar System
The late evening July Sky
This map shows the constellations seen towards the south at about 10pm BST in mid July. The most prominent star, just a little west of South, is Arcturus in Bootes. It is the second (after Sirius) brightest star in the northern sky. High overhead towards the north (not shown on the chart) and up to the right of Arcturus lies Ursa Major with its prominent grouping of the Plough. As one moves southwards to the left of Bootes one first crosses the constellation Hercules with its magnificent globular cluster, M13, and then across the large but not prominent constellation Ophiucus until, low above the southern horizon lie Sagittarius and Scorpius. Those in the south of the UK - and even better in Southern Europe - will spot the bright red star Antares. Rising in the east 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".
The constellation Ursa Major
The stars of the Plough, shown linked by the thicker lines in the chart above, form one of the most recognised star patterns in the sky. Also called the Big Dipper, after the soup ladles used by farmer's wives in America to serve soup to the farm workers at lunchtime, it forms part of the Great Bear constellation - not quite so easy to make out! The stars Merak and Dubhe form the pointers which will lead you to the Pole Star, and hence find North. The stars Alcor and Mizar form a naked eye double which repays observation in a small telescope as Mizar is then shown to be an easily resolved double star. A fainter reddish star forms a triangle with Alcor and Mizar.
Ursa Major contains many interesting "deep sky" objects. The brightest, listed in Messier's Catalogue, are shown on the chart, but there are many fainter galaxies in the region too. In the upper right of the constellation are a pair of interacting galaxies M81 and M82 shown in the image below. M82 is undergoing a major burst of star formation and hence called a "starburst galaxy". They can be seen together using a low power eyepiece on a small telescope.
Another, and very beautiful, galaxy is M101 which looks rather like a pinwheel firework, hence its other name the Pinwheel Galaxy. It was discovered in1781 and was a late entry to Messier's calalogue of nebulous objects. It is a type Sc spiral galaxy seen face on which is at a distance of about 24 million light years. Type Sc galaxies have a relativly small nucleus and open spiral arms. With an overall diameter of 170,000 light it is one of the largest spirals known (the Milky Way has a diameter of ~ 130,000 light years).
Though just outside the constellation boundary, M51 lies close to Alkaid, the leftmost star of the Plough. Also called the Whirlpool Galaxy it is being deformed by the passage of the smaller galaxy on the left. This is now gravitationally captured by M51 and the two will eventually merge. M51 lies at a distance of about 37 million light years and was the first galaxy in which spiral arms were seen. It was discovered by Charles Messier in 1773 and the spiral structure was observed by Lord Rosse in 1845 using the 72" reflector at Birr Castle in Ireland - for many years the largest telescope in the world.
Lying close to Merak is the planetary nebula M97 which is usually called the Owl Nebula due to its resemblance to an owl's face with two large eyes. It was first called this by Lord Rosse who drew it in 1848 - as shown in the image below right. Planetary nebulae ar the remnants of stars similar in size to our Sun. When all possible nuclear fusion processes are complete, the central core collpses down into a "white dwarf" star and the the outer parts of the star are blown off to form the surrounding nebula.
The constellation Hercules
Between the constellation Bootes and the bright star Vega in Lyra lies the constellation Hercules.The Red Giant star Alpha Herculis or Ras Algethi, its arabic name, is one of the largest stars known, with a diameter of around 500 times that of our Sun. In common with most giant stars it varies its size, changing in brightness as it does so from 3rd to 4th magnitude. Lying along one side of the "keystone" lies one of the wonders of the skies, the great globular cluster, M13. Just visible to the unaided eye on a dark clear night, it is easily seen through binoculars as a small ball of cotten wool about 1/3 the diameter of the full Moon. The brightness increases towards the centre where the concentration of stars is greatest. It is a most beautiful sight in a small telescope. It contains around 300,000 stars in a region of space 100 light years across, and is the brightest globular cluster that can be seen in the northern hemisphere.
The constellation Virgo
Virgo, in the south-east after sunset this month, is not one of the most prominent constellations, containing only one bright star, Spica, but is one of the largest and is very rewarding for those with "rich field" telescopes capable of seeing the many galaxies that lie within its boundaries. Spica is, in fact, an exceedingly close double star with the two B type stars orbiting each other every 4 days. Their total luminosity is 2000 times that of our Sun. In the upper right hand quadrant of Virgo lies the centre of the Virgo Cluster of galaxies. There are 13 galaxies in the Messier catalogue in this region, all of which can be seen with a small telescope. The brightest is the giant elliptical galaxy, M87, with a jet extending from its centre where there is almost certainly a massive black hole into which dust and gas are falling. This releases great amounts of energy which powers particles to reach speeds close to the speed of light forming the jet we see. M87 is also called VIRGO A as it is a very strong radio source.
Below Porrima and to the right of Spica lies M104, an 8th magnitude spiral galaxy about 30 million light years away from us. Its spiral arms are edge on to us so in a small telescope it appears as an elliptical galaxy. It is also known as the Sombrero Galaxy as it looks like a wide brimmed hat in long exposure photographs.
The constellations Lyra and Cygnus
This month the constellations Lyra and Cygnus are rising in the East 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.
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!
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.