The Night Sky June 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
Titan seen behind Saturn's Rings
Image: Cassini Imaging Team, ISS,JPL,ESA,NASA
This summer, Saturn's ring plane will point directly at the Sun, and already the rings make quite a small angle to the line of sight from Earth. This beautiful image of cloud-shrouded Titan seen behind the A and F rings of Saturn thus seems appropriate. Appearing just above Titan is the tiny moon Epimetheus which orbits just outside the thin, dark F ring. The prominent dark region seen in the A ring is Encke's Division which is 200 miles (325 km) across. One of the several narrow ringlets is visible within the division in which also lies the orbit of the 16 mile (26 km) diameter moon, Pan.
Highlights of the Month
June10th: A nice line-up of Saturn's brightest satellites.
To see some of Damian Peache's Saturn Images: Damian Peache's website
Saturn is now setting in the south-western sky after nightfall in the constellation of Leo. It lies well below the body of Leo some 8 degrees below the star Theta Leonis. One advantage of the rings lying at such a close angle (~3.5 degrees) to our line of sight is that there is less glare to hide Saturn's satellites. Late on the evening of June 10th, five of Saturn's brightest satellites nicely line up to the east of the planet and, given a transparent night, should make a very nice sight in a telescope of 6 or more inches in diameter. One should easily spot Titan at magnitude 8.4, and Rhea at magnitude 9.8, however, Dione(+10.5)and Tethys(+10.3) will be harder to observe and you may not find Enceladus at +11.8 magnitudes. Use as high a magnification as you can to just encompass Saturn and its satellites as this will make the sky background darker and so make the satellites show up more easily.
June 19th: 03:30 UT - Mars and Venus below a crescent Moon
Venus passes just 2 degrees below Mars around the 19th of June with, on that morning, a thin crescent Moon lying just 7 degrees just up to the right of Mars. One for early risers!
June: 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 just take a look towards the north and you might just spot them!
June4th: Spot Neptune close in the sky to Jupiter.
During June, Jupiter and Neptune are close together in the sky and are at their closest on June 4th when Neptune, at magnitude 7.9, lies up and to the right of Jupiter, at magnitude -2.5. It will make a nice triangle with Jupiter and the 5.1 magnitude star Mu Capricornus down to its lower right. Given a transparent sky it should be easily spotted in 8 x 40 binoculars just half a degree away from Jupiter. It remains close to Mu Capricornus throughout the month but with Jupiter moving relatively further to the left. Could well be worth getting up for!
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 in the last week or so of July 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||first quarter||full moon||last quarter|
|June 24th||June 1st||June 9th||June 17th|
Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images
Saturn is seen as twilight deepens lying in Leo - but somewhat below the main body of the Lion. Its magnitude is +1 - not as bright as usual, with Saturn significantly less bright this year than it sometimes is: the rings are very close to edge on and thus there is less apparent reflecting area. During June they are at an angle of just 3.5 degrees from the line of sight. The rings will be seen (or rather - not seen) edge-on later this year and it will not be until 2016 that they will be at their widest again. A small telescope will easily show its largest moon, Titan, and show some bands around the surface. See also the highlight above
Mercury: reaches what is called "Western Elongation" on the 13th June which is when it lies furthest in angle from the Sun and seen before sunrise. However its elevation will be very low, and binoculars will almost certainly be needed to spot it (NB before the Sun rises!) at magnitude +0.6 given a very low north-eastern horizon.
Mars still remains low in the pre-dawn sky this month but, as it rises increasingly earlier than the Sun as the month progresses, will become easier to spot. It has a magnitude of +1.2. By the end of the month, the angular separation from the Sun has increased to 47 degrees which helps, but as the ecliptic makes a small angle to the horizon, even then Mars will then be just 23 degrees above the horizon as the Sun rises on the last day of June. We will have to wait a month or so until it will be seen easily as the nights get longer! See highlight above.
Venus is now visible in the pre-dawn sky. It will only lie 14 degrees above the horizon as the Sun rises on the first of June, so will be easier to spot later in the month. It is at magnitude -4.2 at mid month, just to the lower right of Mars. An interesting fact about its brightness is that it stays pretty constant at about -4.4 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 and the effective reflecting area of Venus as seen from Earth remains pretty constant. See highlight above.
Find more planetary images and details about the Solar System: The Solar System
The late evening June Sky
This map shows the constellations seen towards the south at about 11pm BST in mid June. High over head towards the north (not shown on the chart) lies Ursa Major. As one moves southwards 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 Scorpio. To the right of Hercules lie the arc of stars making up Corona Borealis and then Bootes with its bright star Arcturus. 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.