Explore Astronomy

Astronomy Picture of the Day
« February 2018

The Night Sky March 2018

Compiled by Ian Morison

See highlight above.

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.


The author's: Astronomy Digest

which, over time, will provide useful and, I hope, interesting articles for all amateur astronomers.   A further aim is to update and add new material to link with the books recently published by Cambridge University Press and which are described on the home page of the digest.  It now includes over 40 illustrated articles.

Image of the Month

NGC 7331

The galaxy NGC 7331
Image HST- NASA/ESA.D.Milisavljevic (Purdue University)

This is a Hubble Telescope image of the spiral galaxy NGC 7331 which lies some 50 million light years away in the constellation Pegasus.   Though bright, it was not included in the Messier Catalogue.   The spiral arms show both giant clusters of massive blue stars as well as many active star formation regions highlighted by the reddish glow of Hydrogen Alpha emission.   The bright central region, which harbours a supermassive black hole, glows in the yellowish light of older, cooler stars .

Highlights of the Month

March 2nd to 4th after sunset: Venus and Mercury within 1.3 degrees of each other.

Venus and Mars together in the twilight sky..
After sunset on these three evenings and given a clear sky and a low western horizon, you should be able to spot Venus and Mercury.   Their closest is on the 3rd when they are just 1.1 degrees apart.   Binoculars might be needed to penetrate the skys residual brightness, but please do not use them until after the Sun has set. [Note: The sky brightness has been reduced in the chart.]

March 10th/11th before dawn: Saturn, Mars and a waning Moon.

Saturn amd Mars Mars below a waning Moon
If clear before dawn on the 10th and 11th, looking just east of south, one should see a waning crescent Moon lying to the upper left of Mars on the 10th and Saturn on the 11th.

March 19th after sunset: Venus, Mercury and a very thin crescent Moon

Venus, Mercury and a very thin crescent Moon.

Looking west after sunset on the 19th and given a very low western horizon, one might be able to spot Venus near Mercury which is close to maximum elongation from the Sun.   A very thin crescent Moon, just two days after new, will be seen up to their left.   Binoculars may well be needed, but please do not use them before the Sun has set.   A tough observing challenge!   [Note: the sky brightness has been reduced in the chart.]

March 23rd evening: The Moon in the Hyades Cluster


In the evening of the 23rd of the month, the Moon, coming towards first quarter, will lie within the Hyades cluster.   After it has set from the UK it will occult Aldabaran which is a red giant star lying between our solar system and the cluster.

March 8th and 24th: 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 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!

The Alpine Valley
The Alpine valley and the crater Plato

M16, the Eagle nebula, imaged with the Faulkes Telescope

Messier 16 - The Eagle Nebula
Image: Daniel Duggan
Faulkes Telescope North.

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

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
March 17th March 24th March 2nd March 9th

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


A Cassini image of Jupiter . Nasa

Jupiter rises just before midnight at the beginning of the month and about one hour earlier by month's end.   Initially it has a 39 arc second disk, shining at a magnitude of -2.2 but, as the month progresses, its apparent diameter increases to 42.5 arc seconds and it brightens to magnitude -2.4.   Jupiter will transit before dawn and so will enable the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Gallilean moons visible in a small telescope.   Sadly, Jupiter, lying in Libra during the month, is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian.   Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.


The planet Saturn. Cassini - Nasa

Saturn, at the start of its new apparition, rises at around 3 am at the start of the month and just after 2 am at its end.   With an angular size of ~16.3 arc seconds it climbs higher before dawn and so becomes easier to spot as the month progresses.  Its brightness increases from +0.6 to +0.5 magnitudes during the month.   The rings were at their widest a few months ago and are still, at 26 degrees to the line of sight, well open.   Saturn, lying in Sagittarius, is just 3 degrees above the topmost star of the 'teapot'.   Sadly, even when at opposition later in the year it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian.   Atmospheric dispersion will thus greatly hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

See highlight above.


Messenger image of Mercury Nasa

Mercury gives us its best evening apparation this month when it reaches its peak height above the western horizon on March 15th when, at greatest elongation, it lies some 18 degrees east of the Sun.   However, by this time its magnitude has dropped from -1.3 at the beginning of March to -0.4 magnitudes.   Its magnitude continues to fall, dropping to +0.9 by 20th and soon after will be lost in the Sun's glare.   Mercury flirts with Venus during the month as detailed in the highlights.

See highlights above.


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

Mars starts the month in Ophiuchus but, moving quickly, moves into Sagittarius on the 12th as it approaches Saturn.   Now a morning object, it rises at around 2 am at the start of the month.   During the month, Mars has a magnitude which increases from +0.8 to +0.3 and an angular size of just 7, increasing to 8.5, arc seconds so it will be hard to spot details on its salmon-pink surface.   It will only reach an elevation of ~14 degrees before dawn at the start of the month and just 12 degrees by month's end.

See highlight above.


Venus showing some cloud structure

Venus, seen low in the west after sunset, shines at magnitude -3.9 all month with an angular size of ~10.3 arc seconds.   Venus rises a little higher in the sky as March progresses, initially setting around one hour after the Sun but increasing to an hour and a half by month's end.   It has two near conjunctions with Mercury as described in the highlights above.

Radar Image of Venus
Radar image showing surface features

See highlights above.

The Stars

The Early Evening March Sky

March-early evening
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 - 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


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 c