Night Sky Notes – March 2018

Night Sky notes for March 2018        Geoff Mitchell

The March night sky now heralds the spring constellations as we head towards the vernal equinox on March 20th.  The bright planet Jupiter is well placed high in the south east by mid evening.  The spring night sky contains many fine objects to view with both binocular and small telescopes and this month has a few notable events of special interest.

The Milky Way stretches from the constellation of  Auriga , marked by the bright star Capella in the east up into Perseus  and through the `W` shaped constellation of Cassiopeia high overhead and down along the cross shaped constellation of Cygnus  low in the west . This faint band of stars best seen on dark moonless evenings

In the north Ursa Major, The Plough or The Great Bear is seen low with its handle or tail pointing to the horizon mid evening. Use the right hand pair of stars Dubhe and Merak (The pointers) to find the faint pole star Polaris and the position of North.

Look to the west early evening to see the brilliant planet Venus shining brightly. Telescopes shows Venus has phases (like our Moon). Over the coming months Venus phase reduces as greatest elongation approaches (August 2018) .During early March  Mercury also is placed close to Venus in evening twilight , conjunction March 4th has Mercury just 1.4° N of Venus.  An alignment of a 1.5%, thin waxing crescent Moon with Venus and Mercury is visible in evening twilight on March 18th.

Also in the south west, the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus .The Hyades star cluster makes the characteristic `V` shaped asterism in the constellation of Taurus and is noted for the bright, red foreground star Aldebaren in Arabic Al Dabaran is `The follower ` of the Pleiades across the skies, in old English colloquially known as `the eye of the bull`..

By early evening the familiar winter constellations of Orion (The Hunter) is now slipping into the western skies making way for the spring constellations rising in the east.

The constellation of Gemini is easily recognised by the two bright stars Castor and Pollux and the  characteristic rectangular shape  of stars . The western end of the constellation is embedded within the rich star fields of the Milky Way. M35 an open cluster seen as a misty patch in binoculars is a very nice sight when viewed telescopically.

The spring constellation of Leo rises by mid evening, the brightest star Regulus and the `reversed question mark ` shaped star asterism of `The Sickle` makes this an easily recognisable constellation. Leo stretches eastward and is marked at the tail end by the star Denebola.  Leo contains some moderately bright galaxy pairs visible in moderate sized telescopes on moonless evenings.  M65/M66 and NGC 3628 form the famous galaxy triplet, all three galaxies being visible in the same telescopic field of view.

Mid way between Castor and Pollux (Gemini) and Regulus (Leo) lies the obscure constellation of Cancer (the Crab) , with faint stars in the shape of an inverted `Y`  the most striking feature is the splendid open cluster M44  ( The Beehive  Cluster ) or Praesepe  . The cluster is visible to the unaided eye as twice the apparent size of the Moon misty patch, is a magnificent sight when viewed with binoculars  or low magnification telescope. To the south of M44 lies another nice open cluster M67.

This is a prelude to the galaxy rich spring skies visible in the coming months as the constellations of Virgo and Coma Berenices can now be seen rising by late evening. The Virgo cluster of Galaxies has many relatively bright galaxies visible in moderate sized telescopes on moonless clear evenings   March 20th (the equinox)  has equal day and night,  the Sun now crosses north of the celestial equator , Spring  in the northern hemisphere has begun.  Note that UK clocks change to BST (add 1 hour) on Sunday March 25th.

Comet 2016 R2 PanSTARRS is a faint 12.5m magnitude object in Perseus enroute for perihelion passage in May 2018, but at over 2AU from the Sun, the comet with a 20,800 year period will require a large telescope to see it.

Planets in March 2018

Mercury is at low in evening twilight, greatest elongation E on March 17th, Conjunction with Venus March 4th.

Venus shines brightly and is positioned low in south west after sunset visible in evening twilight.  Venus the crescent Moon and Mercury are a nice view on March 18th at 6:30 pm.

Mars is an early morning object low in dawn twilight with Saturn in the constellation of Sagittarius.

Jupiter shines brightly low in dawn twilight, low in the constellation of Libra.

Saturn is low in UK skies in 2018 in the constellation of Sagittarius however the rings are well presented.

Uranus is poorly placed in evening twilight.

Neptune is positioned in our daytime skies – best seen in autumn skies

Moons phases in March 2018

New Moon         Mar 17th                              Moonless, best time for deep sky observing. (Solar eclipse)

First Quarter      Mar 24th                             Best days to see shadow details in lunar craters (early evening)

Full Moon            Mar 2nd /Mar 31st              Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter      Mar 9th                                Moon visible in daytime skies.  Do not look directly at the Sun.

There are two Full Moons in calendar March, the first is the Buck Moon the second Full Moon is therefore a blue moon (nothing to do with colour).  Experience the Moon Illusion at moonrise /moonset, against foreground objects such as trees or buildings, the moon looks rather large (an optical illusion)

Spring Equinox   March 20th 16:16 UT, Sun crosses back north of celestial equator.

Meteor shower s      Virginids show some slow meteors with long trails, peaking during April

The highlights of the month

Venus and Mercury close conjunction March 4th, evening twilight.  (Unaided eye / binocular)

1.5% Waxing crescent Moon with Venus and Mercury aligned low in evening twilight March 18th

March skies, Milky Way visible high overhead on moonless evenings in darker skies.

Double cluster, on the Perseus /Cassiopeia border high overhead, nice pair of star clusters.

Pleiades (Seven Sister’s) star cluster (M45) now low in south west, best seen with binoculars.

Beehive cluster (M44) visible to the unaided eye but best seen with binoculars.

Telescopic triplet of galaxies M65/M66/NGC3628 in the constellation of Leo.

The moon occults the star Aldebaran at 23:38 on March 22nd as the moon sets at midnight.

Moon visibility

The first chance to see the crescent moon is on March 18th after sunset (Moonset 7:15 pm)


More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website

Sky looking south at 8pm, mid March 2018

Mar - South


Orion is placed in the south west, draw a line through the belt stars, down to the bright star Sirius (which can appear to twinkle at low elevation) . Also known as The Dog Star, Sirius is in the constellation Canis Major (Greater Dog), whist the star Procyon is in the constellation Canis Minor (Lesser Dog).  Extend a line though Orion’s belt upwards to find the red star Aldebaren in the constellation of Taurus and the Seven Sister’s star cluster.

Gemini is placed high in the south with Castor leading Pollux across the sky. To the south east the constellation of Leo noted by the bright star Regulus and the `Sickle` asterism of stars and outstretched body resembles a crouching lion , with the star Denebola at the tail end. Between Pollux and Regulus, Jupiter shines brightly and binoculars show the nice `Beehive` star cluster M44 in the constellation of Cancer.

Sky looking east at 8pm mid March 2018

Mar - East

The spring constellations now appear in the eastern sky by mid evening. The orange star Arcturus is found by following the curve of stars in the handle of the Plough down. The constellation of Bootes, resembles a `kite` or `Club ` in shape.  Izar is a beautiful orange/ blue double star visible in small telescopes.


Sky looking north at 8pm mid March 2018

Mar - North

The Plough stands on its handle follow the pointer’s Dubhe and Merek to find the polestar Polaris

The `W` shaped constellation of Cassiopeia looks more like an `M` and is on the opposite side of the                 polestar to the Plough.

Sky looking west at 8pm mid March 2018

Mar - West

Venus shines brightly low in the west shortly after Sunset. Later in the evening Pegasus and Andromeda stand vertically sink towards the western horizon.  In March the ecliptic is inclined steeply around the time of the equinox.

Highlights of the month.

Close conjunction of Venus and Mercury – evening twilight  March 3rd /4th  (After sunset )

Mar - Venus

Crescent Moon , Venus and Mercury  align in evening twilight (March 18th ) 6:30pm

Mar - Moon

Scale   5° is approximate field of view of a pair of 10x 50 binoculars