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« February 2013

Image of the Month

The Trifid Nebula, M20

Subaru Telescope (NAOJ, Hubble Space telescope, ESA,NASA, Martin Pugh; processing by Robert Gendler.

The Trifid Nebula is a star formation region in the constellation of Sagittarius, the Archer, that lies at a distance of about 9,000 light years and spans a distance of about 10 light years.   The three prominent dust lanes that come together in the centre give it its name.   It is the ultra-violet light from a single massive star at its heart that excites the surrounding gas to glow whilst its visible light shows the wonderful detail in the dust lanes.   This beautiful image is the work of Martin Pugh, who provided the colour data, and Robert Gendler who assemble the image using additional imaging data from the HST and Subaru Telescopes.   Wonderful!

Highlights of the Month

March 9th to 20th - after sunset: Comet PanSTARRS

This month we have a chance to spot what may be the brightest comet seen for some time.   Comet PanSTARRS was discovered some two years ago when it lay between the orbits of Saturn and Jupiter - having a brightness of just 19th magnitude.   It is named after the Panoramic Survey Telescope and Rapid Response System.   It reaches perihelion, when closest to the Sun, on March 10th at a distance from the Sun of just 0.3 AU and so inside the orbit of Mercury.   At our latitudes it is likely to be at its best between March 8th to 20th with the 12th to 17th optimum.   Its magnitude is predicted to be -0.2 on March 10th, dimming to +1.3 on the 20th and down to +3.6 by month's end.   The azimuth at which it will be seen moves northwards during the month starting at azimuth 260 on the 9th, 270 on the 13th, 280 on the 18th and at 310 degrees azimuth on the 28th. It will be very low above the horizon so you will need to get to a high observing location with an unobstructed view to the west and north-west.   It should lie just above a thin crescent Moon on the 12th making, if clear, a wonderful imaging opportunity!   Another great imaging opportunity will occur next month on April 4th when, at similar magnitude, it passes close to M31,the Andromeda galaxy

The image at right was taken on the 13th March from Henbury, Cheshire and is a stack of 16 individual images taken with a Nikon D7000 DSLR and 80 mm refractor.   The sky was still quite bright at the time and the comet was only visible in binoculars - but actually looked just like a comet should and was, pleasingly, just where the chart showed.   The sky brightness also limits the length of the tail that can be imaged.

February - Jupiter, still in good view

Jupiter, now moving westwards, still lies in Taurus and so is high in the ecliptic and hence, when due south, is at an elevation of ~60 degrees.   It is looking somewhat different than in the last few years as the north equatorial belt has become quite broad.   The Great Red Spot is currently a pale shade of pink but can be easily seen as a large feature in the South Equatorial Belt.   Jupiter was at opposition on the 3rd of December so, this month, will cross the meridian at sunset and so will be seen in the west during the evening.   After its apparition next year it will be moving towards more southerly parts of the ecliptic so will be at lower elevations when crossing the meridian and will thus be seen through thicker layers of the atmosphere.

The features seen in the Jovian atmosphere have been changing quite significantly over the last few years - for a while the South Equatorial Belt vanished completely but has now returned to its normal wide state.   The diagram on right shows the main Jovian features as imaged by the author at the beginning of December 2012.

The image by Damian Peach was taken with a 14 inch telescope in Barbados where the seeing can be particularly good.   This image won the "Astronomy Photographer of the Year" competition in 2011.

See more of Damian Peach's images: Damian Peaches Website"

March: Look for the Great Red Spot on Jupiter

This list gives some of the best evening times during March to observe the Great Red Spot which should then lie on the central meridian of the planet.

2nd   20:04         26th 20:02

4th   21:43         28th 21:41

9th   20:53         31st 19:12

14th  20:03

16th 21:42        

19th 19:13        

21st 20:52

March 17th - The Moon and Jupiter in Taurus.

After sunset on the 17th, the Moon will join Jupiter in Taurus to join the Hyades and Pleiades clusters.

March 29th Midnight : Saturn with the Moon and Spica

The Moon, near full, joins Saturn and Spica in the southern sky.

March 3rd and 20th: The Alpine Valley

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 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 is a thin rill runs along its length which is quite a challenge to observe.  The dark crater Plato will also be visible nearby.   You may also see the shadow cast by the mountain Mons Piton lying not far away in Mare Imbrium.   This is a very interesting region of the Moon!

M16, the Eagle nebula, imaged with the Faulkes Telescope

The Eagle Nebula, M16, imaged by Daniel Duggan.
This image was taken using the Faulkes Telescope North by Daniel Duggan - for some time a member of the Faulkes telescope team.   It is a region of dust and gas where stars are now forming.   The ultraviolet light from young blue stars is stripping the electrons from hydrogen atoms so this region contains ionized hydrogen and is called an HII region.   As the electrons drop back down through the hydrogen energy levels as the atoms re-form, red light at the H alpha wavelength is emitted.   This "true colour" image is composed of red, green and blue images along with a narrow band H alpha image.   A Hubble image of the central region, called the "Pillars of Creation", has become quite famous but looks green/blue in colour.   This is a false colour image where the H alpha image has been encoded as green!

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

Observe 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.)

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 Early Evening March Sky

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

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 - 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 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.

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

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 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.

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 constellation 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.

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 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.

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Last updated: Thursday 14 March 2013 (07:42)
Page Editor: Ian Morison