The Night Sky June 2007
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
Cats Eye Planetary Nebula -click on image to download a full resolution version
Image:Hubble Space Telescope - NASA,ESA,HEIC and the Hubble Heritage Team
This beautiful planetary nebula represents a brief phase in the life of a star like our Sun. The central star has blown off concentric shells of material in succesive outbursts. The gas is excited by ultra violet light form the dying star which will become a white dwarf in the course of time. The Cats Eye nebula lies at a distance of about 3000 light years and spans some half a light year across. Our Sun will pass through this dynamic phase in its life some 5 billion years in the future.
The Moon
The passage of the Moon through the Earth's shadow March 2007: Cape Newwise 200 mm telescope and Nikon D80 camera.
Ian Morison, Jodrell Bank Observatory
| new | first quarter | full moon | last quarter |
|---|---|---|---|
| June 15th | June 22nd | June 1st | June 08th |
Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images
Highlights of the Month
June: Jupiter at Opposition
Jupiter - showing the Red Spot and the shadow of one of its Moons.
Image by Damian Peache using a 9.25 Celestron Schmidt Cassegrain Telescope.
To see more of Damian Peache's Images: Damian Peache's website
On the 5th/6th of June Jupiter is in line with the Earth and Sun and will thus be seen due south (and highest in the sky) around midnight UT. As it is opposite the position of the Sun in the sky it is said to be at opposition. A natural consequence of this is that it will then be closest to the Earth and so subtends its maximum angular size of 45.8 arc seconds. It shines with a magnitude of -2.6 up and to the right of the red star Antares in Scorpius. However Jupiter les in the constellation Ophiuchus, part of which dips down between Scorpius and Sagittarius. Sadly, this is almost at the most southerly point of the ecliptic (the path of the Sun, and near to which the planets are found) so Jupiter will not be high in the sky for observers at our northern latitudes - about 16 degrees elevation from central England, but only ~11 degrees from northern Scotland. This means that it will be seen through quite a substantial atmosphere and so our views will not be as good as when Jupiter is higher in the sky. There is a second problem in that the atmosphere acts somewhat like a prism with the blue image of Jupiter appearing about 4 arc seconds above the red image. This will both add "false colour" to the image and blur it as well. One should thus use colour filters to observe it at a particular part of the spectrum. Different colours can help bring out different aspects of the surface. Light blue will darken the red spot and make the equatorial bands more prominent, whilst a light yellow filter can help bring out detail in the polar regions. The refractive aspects of the atmosphere will make it difficult to photograph Jupiter with a Toucam or other colour webcam. The best results will come if red, green and blue images are obtained separately using colour filters. Even better results will be obtained with narrow band filters such as OIII for Green and H-Alpha for the red.
A small telescope (or even binoculars resting on a wall to steady them) will allow you to observe the 4 bright Galilean Moons, Io, Europa, Ganymede and Callisto, discovered by Galilo Galilei in 1610. Sometimes the Moons cast a shadow on the surface which can be seen as a black dot in moderate sized telescopes. A telescope will enable you to easily see the equatorial belts - clouds at differing altitudes - and you may also spot the great red spot, though it is not quite so prominent now as it can sometimes be.
June 18th: The Crescent Moon and Venus
Venus and the Crescent Moon
During the day on the 18th June, the Moon will occult (move in front of) the planet Venus. As dusk falls, it will have moved to the south of Venus and will be just 3 degrees to its upper left. If clear, this could make a nice image using a short focal length refractor as the Astronomica 80ED reviewed on this website.
The Planets
A montage of the Solar System. JPL / Nasa
Jupiter
A Cassini image of Jupiter . Nasa
Jupiter- see highlight above.
Saturn
The planet Saturn. Cassini - Nasa
Saturn lies in the constellation Leo, but very close to the boundary with Cancer, about 11 degrees to the right of Leo's brightest star Regulus. It is now in the south-western sky as night falls but will soon be lost in twilight. Its magnitude is ~ +0.5 (reducing to +0.6 during the month) and its globe subtends an angle of ~17 arc seconds. On the 18th of June Saturn, the crescent Moon and Venus will subtend 8 degrees across the sky in a nice grouping.
The rings are closing and are now about 13 degrees from edge-on, so Saturn is shining less brightly than during the previous few years whilst the rings have been more open. Saturn is still, however, a beautiful sight in a small telescope. A 4 to 6 inch telescope will also easily show Saturn's largest moon, Titan, and an 8 inch three or four more.
The image was taken as the Cassini spacecraft neared Saturn at the start of its exploration of the planet and its moons - particularly Titan.
Mercury
Mariner 10 composite image of Mercury. Nasa
Mercury During the first week of June there is a chance to see elusive Mercury above the north-western horizon after sunset. Binoculars will help pick it out. Try to get to a location with a low western horizon and be there by sunset so you can see the point on the horizon where the Sun has set. Mercury should be found perhaps 30 minutes later up and to the south (left) of where the Sun set. It will down and to the right of the planet Venus which, on the second of June forms a line with the stars Pollux and Castor in Gemini.
Note that the blank region in the image above is simply because this part of Mercury's surface has not yet been imaged in detail.
Mars
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa
Mars, in Pisces, has risen to about 20 degrees elevation above the south-eastern horizon as morning twilight begins. Its disk is just 6 arc seconds across and it shines at magnitude +0.8. We really need to wait a few months before we see it well as it will not be well placed until August. Mars will reach opposition in December - a highlight of the winter months
Venus
Venus showing some cloud structure
Venus dominates the western sky after sunset, setting a few hours after the Sun. With a magnitude of -4.3 it can hardly be missed! It stands about as high above the horizon as we can ever see it. It reaches its greatest eastern elongation on June 9th when its disc will be half illuminated (like the Moon at first quarter). As the months progress from then, Venus will go through its crescent phases and the angular size will increase. This has the interesting consequence that the "apparent reflecting area" stays almost constant and hence the magnitude stays very close to -4 for quite a few months. It was the fact that Venus could show almost full phases that showed Galileo that Venus at times must lie beyond the Sun and hence the Copernican theory of ther Solar system must be correct. See also the highlight above.
Radar image showing surface features
Find more planetary images and details about the Solar System: The Solar System
The Stars
The late evening June Sky
The June Sky in the south - late evening.
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
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.
M81 and M82
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).
M101 - The Ursa Major Pinwheel Galaxy
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.
M51 - The Whirlpool Galaxy
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.
M97 - The Owl Planetary Nebula Lord Rosse's 1848 drawing of the Owl Nebula
The constellation Hercules
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 Globular Cluster M13 in Hercules. Image by Yuugi Kitahara
The constellation Virgo
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.
The Giant Elliptical Galaxy M87 HST image showing the jet
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.
M104 - The Sombrero Galaxy
The constellations Lyra and Cygnus
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
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!
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
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
Cygnus
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.
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.
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.
Brocchi's Cluster - The Coathanger
