The Night Sky March 2008
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
Mercury as photographed by the Messenger spacecraft
Image: Messenger, NASA JHU APL, CIW
For the first time in very many years, a spacecraft, called Messenger, has flown by Mercury when the image above was taken. I make no apologies for having a second image of Mercury in as many months as this is the best image of Mercury that has ever been taken! Later, Messenger will return and finally go into orbit so enabling detailed images of the surface to be taken. In the full resolution image details as small as 10 km in diameter can be seen. This colour image has been made from inages taken through infra-red, red and violet filters.
Highlights of the Month
March: Saturn in the evening sky
Saturn imaged from Earth with an 11 inch telescope.
Image copyright: Damian Peach
To see more of Damian Peache's Images: Damian Peache's website
Saturn is now high in the eastern sky during the evening lying in the constellation of Leo just below and to the left of Leo's brightest star Regulus. As March begins, Saturn lies some 4 degrees from Regulus and, by 20:00 UT, is nearly 30 degrees above the horizon in the east south-east. Saturn reached opposition on February 24th so it is high in the south around midnightand thus in an ideal position to observe in the late evening. It starts the month at magnitude +0.2 with an angular size of ~20 arc seconds and these fall to +0.4 and 19.6 as the month progresses. Saturn is not as bright this year as it sometimes is: the rings are closing (just ~ 8 degrees tilt to us and subtending only 5 arc seconds) and thus there is less apparent reflecting area. The rings will be seen (or rather - not seen) edge on in 2009 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.
Observe a White Dwarf
Eridanus
This is a good month to try to observe a White Dwarf star - the end state of a star like our own Sun. They are about the size of the Earth, but are very hot so can still appear reasonably bright. Omicron-2 is an orange star of magnitude 4.4 in the constellation Eridanus that lies to the right of Rigel. You will be able to pick this up with a pair of binoculars. However if you can use a small telescope with medium power you should spot a faint white 9th magnitude companion - a white dwarf. White dwarfs are very dense and a teaspoon full might weigh as much as a ton! Near the White Dwarf is an 11th magnitude "Red Dwarf" that might be spotted as well.
Observe the Open Cluster M41
Canis Major showing the position of M41
Open Cluster M41
As Sirius is high in the sky during the early evening this month, it is easy to find a nice open cluster - the 41st enty in the Messier Catalogue. It only contains about 100 stars, but some of these are bright "red giant" stars which appear orange to our eyes and make a very nice contrast with the others. It can easily be picked out with binoculars and makes a very nice sight in a small telescope. M41 lies at a distance of about 2300 light years and is around 200 million years old.
Observe the International Space Station
The International Space Station
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.)
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 | first quarter | full moon | last quarter |
|---|---|---|---|
| Mar 7th | Mar 14 th | Mar 21th | Mar 29th |
Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images
The Planets
A montage of the Solar System. JPL / Nasa
Jupiter
A Cassini image of Jupiter . Nasa
Jupiter may now be glimpsed in the pre-dawn sky. At the beginning of the month it is 60 degrees from the Sun, lying in the Constellation of Sagittarius where it remains during the month. At the beginning of March, Jupiter rises at about 05:00 UT, two hours before the Sun, and by month's end it rises at 03:00 UT, some 3 hours before the Sun. However, it is now at the lowest point of the ecliptic in the sky and will only rise to about 11 degrees elevation before sunrise. Thus sadly, this year our views of Jupiter from northern latitudes will be rather poor. Its magnitude is ~-2 throughout March and its angular size increases from 34.4 to 37.3 arc seconds through the month. Despite the low elevation, even a small telescope will show the Galilean Moons as they weave their way around it.
Saturn
The planet Saturn. Cassini - Nasa
Saturn see highlight above.
Mercury
Mariner 10 composite image of Mercury. Nasa
Mercury is at greatest elongation from the Sun on March 3rd - usually the best time to observe it. But,sadly, the angle of the ecliptic to the horizon is very shallow this month so, as the Sun rises, Mercury is only 6 degrees above the horizon and will be very difficult to spot! It will be a touch up and to right of Venus which is just 2 degrees away on the 3rd. Venus and Mercury stay close throughout the month, but its not really the best time to see either!
Mars
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa
Mars and our Earth are now seperating quite quickly so that both the brightness and angular size of Mars fall quite rapidly this month - the magnitude from +0.2 to + 0.8 and the angular size from 9.1 to 7 arc seconds. It starts the month in the constellation Taurus, high in the south after nightfall, but moves into Gemini on the 5th March. On 10th of March it will lie just 2 degrees up and to the right of the open cluster M35 in Gemini.
Venus
Venus showing some cloud structure
Venus is visible very low in the pre-dawn sky this month in close consort with Mercury. However its low elevation will make it hard to spot. As the month progresses, the angular size drops from 11.3 arc seconds to 10.4 arc seconds, but the illuminated area of the surface increases. These two factors which affect its brightness roughly cancel out and the brightness stays throughout the month at -3.8 magnitudes. Venus but may be glimpsed before dawn low in the south-east provided that you have a very low eastern horizon. As it is never that high above the horizon, dispersion in the atmosphere tends to colour its image and it will be seen best in a telescope when a filter is used to observe it at one colour of light such as by the use of a green filter. A narrow band filter, such as an O III filter, will give even cleaner images.
Radar image showing surface features
Find more planetary images and details about the Solar System: The Solar System
The Stars
The Early Evening March Sky
The March Sky in the south - early evening.
This map shows the constellations seen in the south during the early evening. The brilliant constellation of Orion is seen in the south. Moving up and to the right - following the line of the three stars of Orion's belt - brings one to Taurus; the head of the bull being outlined by the V-shaped cluster called the Hyades with its eye delineated by the orange red star Aldebaran. Further up to the right lies the Pleaides Cluster. Towards the zenith from Taurus lies the constellation Auriga, whose brightest star Capella will be nearly overhead. To the upper left of Orion lie the heavenly twins, or Gemini, their heads indicated by the two bright stars Castor and Pollux. Down to the lower left of Orion lies the brightest star in the northern sky, Sirius, in the consteallation Canis Major. Up and to the left of Sirius is Procyon in Canis Minor. Rising in the East is the constellation of Leo, the Lion, with the planet Saturn up and to the right of Regulus its brightest star. Continuing in this direction towards Gemini is the faint constellation of Cancer with its open cluster Praesepe (also called the Beehive Cluster),the 44th object in Messier's catalogue. On a dark night it is a nice object to observe with binoculars. There is also information about the constellation Ursa Major,seen in the north, in the constellation details below.
The Late Evening March Sky
The March Sky in the south - late evening.
This map shows the constellations seen in the south around midnight.
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. It is well worth observing with binoculars to see the Beehive Cluster at its heart. 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.
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 main 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
