The Night Sky May 2010
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
SDO image of the Sun on March 30th Image:NASA/ESA
This is one of the first images of the Sun in the extreme ultraviolet taken by the new Solar Dynamics Observatory (SDO). It will be producing solar images of unprecedented detail with over 1.5 Terrabytes of data being returned to Earth each day! It does rather look as though the Sun is awakening from its deep sleep over the last couple of years!
Highlights of the Month
9th and 10th May: Jupiter and a waning crecent Moon.
Jupiter and the Crescent Moon
Image:Stellarium/IM
9th and 10th May: Jupiter and a Crescent Moon in the pre-dawn sky.
At around 05:00 BST a waning crescent Moon will lie close to Jupiter in the pre-dawn sky. On the 9th it will lie ~6 degrees up to the right of Jupiter whilst on the 10th it will be ~10 degrees away to its left. A first chance to see Jupiter at its new apparition perhaps?
May 16th 10:00 BST: Spot Venus in daytime!
Venus and a crescent Moon on the evening of the 16th.
Image:Stellarium/IM
May 16th: Spot Venus in daylight!
On Sunday 16th May, the Moon passes just below the planet Venus. Its closest approach is at 10:00 BST when the Moon's northern edge is just 0.25 degrees below the planet. At 10 am, the Moon and Venus will lie just 5 degrees south of East at an elevation of ~36 degrees. They lie ~30 degrees away from the Sun, but still be VERY careful when searching for them and keep your binoculars well away form the Sun!! A compass to give you due east as your starting point for scanning the sky would be very useful. The pair, which will lie close to the open cluster M35 in Gemini (1 degree above the Moon) that evening should also make a beautiful target with binoculars as night falls.
May 25th/26th: Schroter's valley on the Moon
Schroter's valley
An interesting valley on the Moon: Schroter's 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 25th) is the bright crater Aristachus, some 41km in diameter. It is a young crater, some 450 million year old and shows some rays projecting from it. It lies close to the 36km diameter crater Herodotus which is close to the starting point for the very interesting "Schroter's Valley". This extends north, then west, for ~97 km and has a width of 6 to 9km. It has a depth of ~1 km. The upper image shows how it appears as seen from Earth in an inverting telescope, whilst the lower is an image looking south taken by the Apollo 15 astronauts.
Schroter's Valley and Aristarchus
28th May 02:00 BST: Sigma Scorpii occulted by the Moon
Sigma Scorpii occulted by the Moon
Image:Stellarium/IM
~2 am BST: Sigma Scorpii is occulted by the Moon.
In the early hours of the morning on the 28th of May the full Moon, seen low in the south, will occult the star Sigma Scorpii. The image shows the situation just before the occultation, but the position of the star relative to the Moon will vary dependent on your location within the UK. It will reappear about 1 hour later.
31st May 02:00 BST: Comet R1 McNaught low on the north-east
Comet McNaught in Andromeda
Image:Stellarium/IM
~2 am BST last few days of May: Comet McNaught.
In the early hours of the morning at the end of May, binocuars should help you spot a comet. During May, Comet McNaught passes low in the north-east below the constellations of, first, Pegasus and then Andromeda. It will be easiest to spot at the very end of the month when it should have reached magnitude 8, so fairly obvious in binoculars. On the 31st, it will lie just below the star Beta Andromedae. This star is on the "star hop" route to M31: starting at the top left star (Alpha Andromedae) of the Square of Pegasus, go left and a touch down to a star and then continue left by the same amount but a touch up to reach Beta Andromedae. Here one normally turns sharp right past one star to get to M31, but instead just drop below Beta Andromedae to find the comet appearing as a "fuzzy" object.
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
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 |
|---|---|---|---|
| May 14th | May 21st | May 28th | May 6th |
Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images
A 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.
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. JPL / Nasa
Jupiter
A Cassini image of Jupiter . Nasa
Jupiter, having passed behind the Sun on the 28th February, has now reappeared in the pre-dawn sky. At the beginning of May it will rise in the east as morning twilight begins and, at magnitude -2.1, could be seen in binoculars given a clear low eastern horizon. During the month it will gradually rise earlier and, by end of the month, will rise about 2:30 BST and brighten to -2.3 magnitude. Best wait a month or so to see it well though. A small telescope will easily pick up Jupiters four Galilean moons as they weave their way around it.
See Highlight above.
Saturn
The planet Saturn. Cassini - Nasa
Saturn may now be easily seen in the south after sunset lying in Virgo down to the lower left of the constellation Leo. It can then be seen for much of the night with a magnitude +0.8 rising (which means getting fainter) to +1 during the month. The angular size of the disc stays around 18.5 arc seconds with the rings extending to ~40 arc seconds. The ring system is still close to edge-on and so will still appear very thin - the reason why Saturn is not a bright as it is when the rings are more open. Due to difference between the orbital inclinations of Saturn and the Earth, the tilt is actually reducing at the moment, starting the month at an angle of ~2 degrees. This will reduce to only 1.7 degrees in late May before the rings finally begin to open out again from the end of June onwards. For the first time in 15 years we are now begining to see the northern face of the rings. A small telescope will easily show its brightest satellite, Titan at magnitude 7.8, and one of 8 inches or more aperture several more.
Mercury
Messenger image of Mercury Nasa
Mercury passed in front of the Sun on April 28th and will appear in the morning twilight sky during the latter part of May reaching its greatest elongation from the Sun on the 26th. However, the ecliptic is at a very shallow angle to the horizon and so Mercury will only lie about 5 degrees above the horizon half an hour before sunrise. You might just be able to pick it out with binoculars given a very low eastern horizon.
Mars
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa
Mars remains visible (at magnitude +0.7 changing to +1.1 during the month) in the south-west after sunset. It is now moving ~1/2 degree a day eastwards from Cancer into Leo. Its angular size angular size drops from 7.3 to 6 arc seconds during the month so details on the surface will be very hard to spot. On the 31st May, it will lie just 3.5 degrees to the right of Regulus.
Venus
Venus showing some cloud structure
Venus is now prominent in the evening sky after sunset in the west north-west. At magnitude -3.9, it will be easily spotted - the brightest object in the night sky after the Moon. With an angular size of 11.4 arc seconds as May begins and increasing to nearly 13 arc seconds by month's end, it will appear in a telescope as a well illuminated disc like that in the accompanying image. It was this observation by Galileo that showed that Venus must orbit the Sun - should it, as in the Ptolomaic system, be moving in an epicycle between the Sun and the Earth, it could never show a fully illuminated disk! It is an interesting fact that Venus's brightness remains pretty constant at ~ -3.8 to -4 all the time that it is visible. As it nears the Earth, it become a thin crescent, but the fact that it is then much nearer to us means that the effective reflecting area remains virtually constant in apparent size.
See highlight above.
Radar image showing surface features
Find more planetary images and details about the Solar System: The Solar System
The Stars
The evening May Sky
The May Sky in the south - after sunset.
This map shows the constellations seen in the south after sunset.
The constellation Gemini is now setting towards the south-west and Leo holds pride (sic) of place in the south with its bright star Regulus. Between Gemini and Leo lies Cancer - which is well worth observing with binoculars to see the Beehive Cluster at its heart. Just into Leo, close to the boundary with Cancer, is the planet Saturn. Below Gemini is the tiny constellation Canis Minor whose only bright star is Procyon. Rising in the south-east is the constellation Virgo whose brightest star is Spica. Though Virgo has few bright stars it is in the direction of of a great cluster of galaxies - the Virgo Cluster - which lies at the centre of the supercluster of which our local group of galaxies is an outlying member. High overhead in the north is the constellation Ursa Major which also contains many interesting objects.
The constellation Gemini
Gemini
Gemini - The Twins - lies up and to the left of Orion and is in the south-west during early evenings this month. It contains two bright stars Castor and Pollux of 1.9 and 1.1 magnitudes respectivly. Castor is a close double having a separation of ~ 3.6 arc seconds making it a fine test of the quality of a small telescope - providing the atmospheric seeing is good! In fact the Castor system has 6 stars - each of the two seen in the telescope is a double star, and there is a third, 9th magnitude, companion star 73 arcseconds away which is alos a double star! Pollux is a red giant star of spectral class K0. The planet Pluto was discovered close to delta Geminorum by Clyde Tombaugh in 1930. The variable star shown to the lower right of delta Geminorum is a Cepheid variable, changing its brightness from 3.6 to 4.2 magnitudes with a period of 10.15 days
M35 and NGC 2158
This wonderful image was taken by Fritz Benedict and David Chappell using a 30" telescope at McDonal Observatory. Randy Whited combined the three colour CCD images to make the picture
M35 is an open star cluster comprising several hundred stars around a hundred of which are brighter than magnitude 13 and so will be seen under dark skies with a relativly small telescope. It is easily spotted with binoculars close to the "foot" of the upper right twin. A small telescope at low power using a wide field eyepiece will show it at its best. Those using larger telescopes - say 8 to 10 inches - will spot a smaller compact cluster NGC 2158 close by. NGC 2158 is four times more distant that M35 and ten times older, so the hotter blue stars will have reached the end of their lives leaving only the longer-lived yellow stars like our Sun to dominate its light.
The Eskimo Nebula, NGC2392, Hubble Space Telescope
To the lower right of the constellation lies the Planetary Nebula NGC2392. As the Hubble Space Telescope image shows, it resembles a head surrounded by the fur collar of a parka hood - hence its other name The Eskimo Nebula. The white dwarf remnant is seen at the centre of the "head". The Nebula was discovered by William Herschel in 1787. It lies about 5000 light years away from us.
The constellation Leo
Leo
The constellation Leo is now in the south-eastern sky in the evening. One of the few constellations that genuinely resembles its name, it looks likes one of the Lions in Trafalger Square, with its manem and head forming an arc (called the Sickle) to the upper right, with Regulus in the position of its right knee. Regulus is a blue-white star, five times bigger than the sun at a distance of 90 light years. It shines at magnitude 1.4. Algieba, which forms the base of the neck, is the second brightest star in Leo at magnitude 1.9. With a telescope it resolves into one of the most magnificent double stars in the sky - a pair of golden yellow stars! They orbit their common centre of gravity every 600 years. This lovely pair of orange giants are 170 light years away.
Leo also hosts two pairs of Messier galaxies which lie beneath its belly. The first pair lie about 9 degrees to the west of Regulus and comprise M95 (to the east) and M96. They are almost exactly at the same declination as Regulus so, using an equatorial mount, centre on Regulus, lock the declination axis and sweep towards the west 9 degrees. They are both close to 9th magnitude and may bee seen together with a telescope at low power or individually at higher powers. M65 is a type Sa spiral lying at a distance of 35 millin klight years and M66, considerably bigger than M65, is of type Sb. Type Sa spirals have large nuclei and very tightly wound spiral arms whilst as one moves through type Sb to Sc, the nucleus becomes smaller and the arms more open.
The galaxies M65 and M66
M65 - Type Sa spiral, 9.3 magnitude M66 - Type Sb spiral, 8.9 magnitude
The second pair of galaxies, M95 and M96, lie a further 7 degrees to the west between the stars Upsilon and Iota Leonis. M95 is a barred spiral of type SBb. It lies at a distance of 38 million light years and is magnitude 9.7. M96, a type Sa galaxy, is slightly further away at 41 million light years, but a little brighter with a magnitude of 9.2. Both are members of the Leo I group of galaxies and are visible together with a telescope at low power.
The galaxies M95 and M96
M95 - Type SBb spiral, 9.7 magnitude M96 - Type Sa spiral, 9.2 magnitude
There is a further ~9th magnitude galaxy in Leo which, surprisingly, is in neither the Messier or Caldwell catalogues. It lies a little below lambda Leonis and was discovered by William Herschel. No 2903 in the New General Catalogue, it is a beautiful type Sb galaxy which is seen at somewhat of an oblique angle. It lies at a distance of 20.5 million light years.
The 8.9th magnitude, type Sb, Galaxy NGC2903
The constellation Virgo
Virgo
Virgo, rising in the east in late evening 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 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
