Astronomy

Astronomy
Astronomy Guide to the Night Sky – April 2018

Astronomy Guide with the Newbury Astronomical Society

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The chart above shows the night sky looking south at about 21:00 BST on 15th April.  West is to the right and east to the left.  The point in the sky directly overhead is known as the Zenith and is shown at the upper centre of the chart.  The curved brown line across the sky at the bottom is the Ecliptic or Zodiac.  This is the imaginary line along which the Sun, Moon and planets appear to move across the sky.  The constellations through which the ecliptic passes are known as the constellations of the ‘Zodiac’.

Constellations through which the ecliptic passes this month are: Aries (the Ram), Taurus (the Bull), Gemini (the Twins), Cancer (the Crab), Leo (the Lion) and Virgo (the Virgin) just appearing over the eastern horizon.

The Milky Way (our Galaxy) appears to rise up from the southern horizon.  It continues up through the constellations of Monoceros, Orion, Gemini, Auriga, Perseus and into Cassiopeia (just off the top right of the chart).

This time of year (Spring) is sometimes referred to as the season if the galaxies because it is the best time to look for galaxies.  A larger telescope is required to see any of the galaxies except M31 the Great Spiral Galaxy in the constellation of Andromeda.  M31 can be seen using a smaller telescope or even a good pair of binoculars.  It is unfortunately disappearing over the western horizon this month and cannot be seen.

There are many galaxies in the Virgo Cluster that is centred on the space between the constellations of Leo, Virgo and Coma Berenices on the center left of the chart.  This time of the year is a good time to look for galaxies.  It is time when we are looking up and out of the spiral structure of our galaxy so we have a clearer view of the deep sky.  Some of the Virgo Cluster galaxies are shown on the chart above.  They are marked with their Messier number in yellow.

Orion is still prominent the evening sky and is easy to find in the south western sky.  The familiar shape of Orion the Hunter is followed across the sky by his hunting dogs Sirius and Procyon.

To the north of Orion are the fairly obvious constellations of Taurus and Gemini.  To the North West and sitting astride the ecliptic is the constellation of Taurus (the Bull).  The Taurus asterism (shape) looks like a squashed cross ‘X’.  At the centre of the cross is a large, faint and dispersed Open Cluster, the Hyades.  It has the bright Red Giant star Aldebaran in the centre.  The real beauty of Taurus is the naked eye Open Cluster M45 the Pleiades, or the Seven Sisters.

Most people with fairly good eyesight can see the brightest six stars in the cluster.  Binoculars will reveal about forty bright stars and the view will be magnificent.  In fact the best view is obtained using binoculars.  A small short focal length telescope will also give a wonderful view but the whole cluster cannot fit into the narrow field of view of most telescopes.  There are a host of smaller stars in the cluster that are too faint to be seen and identified in amateur astronomer’s telescopes.  It is thought there could be more than 1400 stars in total in the cluster.  This month will be our last chance to see this beautiful cluster before it disappears over the western horizon to appear again towards the end of the year.

To the north of Taurus is the constellation of Auriga with its beautiful bright star Capella.  A good pair of binoculars will just reveal a line of three Open Clusters listed in Charles Messier’s Catalogue as M36, M37 and M38.  They can be seen as small patches of light through binoculars but do require a telescope to see as clusters.

Following Taurus along the ecliptic is Gemini (the Twins).  The twin stars Pollux and Castor are easy to find.  There is a lovely Messier Open Cluster M35 in Gemini just off the end of the line of stars emanating from the bright star Castor.  Castor is a double star when seen in a telescope.

To the east of Gemini is the faint and rather indistinct constellation of Cancer (the Crab).  The asterism (shape) of Cancer looks quite uninteresting.  However the Open Cluster Messier 44 (M44) ‘Praesepe’ or the ‘Beehive Cluster’ looks beautiful and like a swarm of bees around an old style straw hive, when seen using binoculars.

Following Cancer is Leo (the Lion) which was the ‘constellation of the month’ last month.

Follow this link to see the full ‘Monthly What’s Up’ guide to the night sky:

http://naasbeginners.co.uk/Whats_up/2017_2018/April2018.htm

To see a full version of this article and a guide to the night sky with charts, read the Newbury Astronomical Society (NAS) – Monthly Magazine for Beginners on the NAS website or come along to the next Beginners meeting on Wednesday 18th April 2018, for details click on the link below.

For details visit the NAS website at: www.naasbeginners.co.uk

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