Explore Astronomy

Astronomy Picture of the Day

« May 2013
July 2013 »


The Night Sky June 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

Kepler's Supernova

Chandra X-ray Image of Kepler's supernova

X-ray: NASA/CXC/NCSU/M.Burkey et al. Optical: DSS


This X-ray image, taken by the orbiting Chandra X-ray observatory, shows the remnant of the supernova seen in 1604 and studied by Johannes Kepler after whom it is named.   It is now thought to have been a Type 1a supernova whose progenitor was a white dwarf star that exploded when it acreted too much material from a companion red giant star and passed the Chandrasekhar limit.   Electron degeneracy pressure could then no longer hold out against gravity and the star collapsed and exploded.   It is the most recent supernova seen to occur in out Milky Way galaxy.

Highlights of the Month

June - Find the globular cluster in Hercules and spot the "Double-double" in Lyra

M13
Use binoculars to find the globular cluster M13 in Hercules and the "Double-double" in Lyra
Image: Stellarium/IM

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 the globular cluster, M13, the best 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!

June 1st - Mercury, Venus and Jupiter form a straight line in the twilight sky.

Three Planets
Mercury, Venus and Jupiter together in the western sky after sunset
Image: Stellarium/IM

About 30 minutes after sunset on the 1st June, Venus and Mercury will lie above the planet Jupiter - perhaps seen for the last time before being lost in the Sun's glare.   You will need a very low western horizon to spot them and binoculars may well be needed to see Mercury but please do not use them until after the Sun has set.

NB: The sky brightness in the chart has been reduced and the planets will not appear so obviously to your eyes!

June 5th to 7th - Spot the asteroid Ceres as it passes just below the star Pollux in Gemini

Ceres
Ceres just one degree below Pollux in Gemini
Image: Stellarium/IM

About one hour after sunset around the 6th of June, seek out the star Pollux - the left "head" of the twins.   The asteroid Ceres, shining at magnitude 8.8 will lie within one degree below with only one other object of this magnitude - a star of magnitude 8.4 - nearby.   It should be easily seen with a pair of binoculars.   Try to observe its movement from the 5th to the 7th. (Clear skies permitting!)

June 10th - A close grouping of Mercury, Venus and a very thin crescent Moon

Planets and the Moon
Mercury, Venus and a this crescent Moon together in the western sky after sunset
Image: Stellarium/IM

About 30 minutes after sunset on the 10th June, Venus and Mercury will be joined by a very thin crescent Moon.   You will need a very low western horizon to spot them and binoculars may well be needed to see Mercury but please do not use them until after the Sun has set.

NB: The sky brightness in the chart has been reduced and the planets will not appear so obviously to your eyes!

June 18th - A Gibbous Moon and Saturn in Virgo

Saturn
Saturn, the Moon and Spica
Image: Stellarium/IM

On the night of the 18th June, the gibous Moon will lie just below Spica, Alpha Virginis, with Saturn visible over to the left.

June 16th/17th: The Alpine Valley

Alpine Valley
Alpine Valley region

An interesting valley on the Moon: The Alpine Valley
These are two good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb (on the 16th) is the Appenine mountain chain that marks the edge of Mare Imbrium.  Towards the upper end you should see the cleft across them called the Alpine valley.   It is about 7 miles wide and 79 miles long.   As shown in the image a thin rill runs along its length which is quite a challenge to observe.  Over the next two nights the dark crater Plato and the young crater Copernicus will come into view.   This is a very interesting region of the Moon!

The Alpine Valley
The Alpine valley and the crater Plato



A Messier Object imaged with the Faulkes Telescope: Messier 27 - The Dumbell Nebula

M27 - The Dumbell Nebula
The Dumbell Nebula
Image:Nik Szymanik
Faulkes Telescope North.

The Dumbell Nebula, imaged by Nik Szymanek.
This image was taken using the Faulkes Telescope North by Nik Szymanek - one of the UK's leading astro-photograpers.   M27 is a planetary nebula, the result of a "nova" expolsion at the end of the life of a star like our Sun.   The core at the centre of the star collapes under gravity until it is about the size of the Earth when "electron degeneracy pressure", resulting from the fact that electrons do not like being squashed too close together, prevents further collapse.   This is called a "white dwarf".   As the dying ember of a nuclear fusion reactor, they are exceedingly hot, but will gradually cool over time.   The outer parts of the star are expelled at high speed into space resulting in the (in this case) spherical nebula surrounding the white dwarf.   The field of the view of the CCD array on the Faulkes Telesocpe is a little too small to encompass the whole nebula.   Once, with a 16 inch telescope under perfect conditions, I visually observed M27 and its central part appeared a vivid iridescent green - the only time I have ever seen colour in a deep sky object!

Learn more about the Faulkes Telescopes and how schools can use them: Faulkes Telescope"



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
June 8th June 16th June 23th June 30th

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.

Plato and the Alpine valley
Plato and the Alpine Valley.

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.



The Planets

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

Jupiter

Jupiter
A Cassini image of Jupiter . Nasa

Jupiter, seen in a very close grouping with Venus and Mercury towards the end of last month and shining at magnitude -1.8, dissapears into the Sun's glare by the second week of June and passes behind the Sun on the 19th to re-emerge into the pre-dawn sky towards the end of next month.

See highlight above.


Saturn

Saturn
The planet Saturn. Cassini - Nasa

Saturn, lying in Virgo, lies just to the west of south as darkness falls.   It is down to the lower left of the first magnitude star Spica, Alpha Virginis and will appear slightly brighter with a yellowish hue.   Saturn's magnitude falls during the month, from +0.3 to +0.5 magnitudes, whilst its angular size decreases from 18.5 to 17.8 arc seconds.   It is closing on the magnitude +4.2 star Kappa Virginis and will be just 0.5 degrees away by month's end.   The good news is that the rings have now opened out to ~17 degrees from the line of sight and will be at their best for 6 years!   (The observed tilt has actually reduced during the last couple of months.)   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

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

Mars passed behind the Sun on April 18th and will appear in the pre-dawn sky this month, rising about 30 minutes before the Sun on the first of June shining at magnitude +1.4.   A telescope would be needed to spot it then but, by the end of the month, it will lie about 7 degrees above the eastern horizon at this time and should be visible in binoculars - but cease using them at sunrise!




Mercury

Mercury.
Messenger image of Mercury Nasa

Mercury.   Following its tight grouping with Jupiter and Venus on the 26th of last month, it will be seen forming a line with them as June begins and, with a magnitude of -0.4, will be the faintest of the three but the highest in the sky.   Mercury reaches greatest eastern elongation (when it is furthest in angle from the Sun) on the 12th June with an angular separation of 24 degrees and will then be best seen about 30 minutes after sunset.   This is the best evening apparition for Mercury this year.   A telescope will show it as an 8 arc-second, slightly, gibbous disc.   On the 18th, it will lie just 2.1 degrees to the left of Venus and will be 1.9 degrees away to its lower left the following night having faded during the month to magnitude +1.2.   By then, binoculars may well be needed to spot it having first found Venus, but do not use them until after the Sun has set.


See highlight above.


Venus

Venus
Venus showing some cloud structure

Venus begins June shining at magnitude -3.8 about 8 degrees above the western horizon half an hour after sunset.   In contrast to many of its apparitions when it is seen high in the sky, the fact that the plane of the ecliptic is at a shallow angle to the horizon in mid-summer means that it will never rise that high in the sky.   It will reach its maximum elevation (~10 degrees) around the 20th-25th of the month.   Now on the far side of the Sun, its 10 arc second disc is almost fully illuminated with a phase of 96% at the start of the month only dropping to 91% by month's end.


See 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 late evening June Sky

May 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
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
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
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
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.

Owl Nebula Owl Nebula
M97 - The Owl Planetary Nebula Lord Rosse's 1848 drawing of the Owl Nebula

The constellation Hercules

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.

Globular Cluster M13
The Globular Cluster M13 in Hercules. Image by Yuugi Kitahara

The constellation Virgo

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.

M87 MERLIN images
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.

The Sombrero Galaxy
M104 - The Sombrero Galaxy

The constellations Lyra and Cygnus

Cygnus and Lyra
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!

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

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
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
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