THE SPRING NIGHT SKY  

April

The Moon at the start of April will be thin having been New on the 29th March, for the Solar Eclipse.  It will be at first quarter on the 5th rising at 10.18 am so it will be a daytime sight for the first week.  Full Moon is on the 13th and all the second week it will be visible at night for Lunarphiles and

Were-Rabbits.  Third quarter is on the 21st.  It will rise at 4am, so for the first half of the third week it'll be a pain to Deep Sky folk but getting better as the week progresses. New Moon will be on the 27th and for all the last week of April it'll be pleasantly co-operative to the DS folk, getting thinner and rising later by the week end.  Of course, it may be like March when we couldn't see it anyway because of the clouds, so come back Moon, you're always better than clouds.

 

The Sun will rise about 0630 at the start of the month and an hour earlier at the end, similarly it sets at 1940pm at the start and at 2030 by the end, giving two hours more daylight this month.

 

Planets.

 

Mars is a bit of a mover this month, moving about 16 Deg across the sky from just south of Elnath, the upper horn tip of Taurus on the 1st, to within half a degree of Mebsuta near the middle of Gemini (the Twins), passing within half a degree of M35 on the 17th.  Whatever its movements, it isn't much to look at now, being a pretty small disc at 5 arcsec.  It will be bright and orange, so still be easy to find.

 

Venus is very bright at –4 mag. in the mornings all month though low just before dawn.  At the start of the month just before dawn you'll find the morning group of Neptune, Venus 6 Deg behind, Uranus, another 17 Deg behind and Mercury a further 3 Deg behind, with the Sun bringing up the rear a further 26 Deg behind.  But the Sun is a bit brighter than the others even before it rises it'll make seeing the planets, other than Venus, very difficult.  Neptune is far ahead enough to be seen, but only with a telescope.  By month end they'll have strung out with Neptune 24 Deg ahead of Uranus which will have overtaken Venus by 11 Deg.  With Mercury another 24 Deg behind and the Sun 20 Deg behind that. Uranus passes Venus on the 18th at about 9am when they'll be less than a third of a degree apart. Though we'll be able to see Venus at that time, if I'm awake, Uranus will be impossible. Tempting to try though.

The one to watch, as the BBC keeps saying, is still Saturn, in Cancer, at 0 mag and yellow. Easy to pick out just in front of Leo's lion shape. Always good to look at in a telescope and better with good seeing when you can see up to 7 of its moons.

Jupiter is a good deal brighter as it rises about 11pm at the start of the month, still too low for good detail to be seen. However, at the month's end it will be rising about 2 hours earlier, about 9pm, and that will mean it's much higher in the sky earlier and will show more detail. So, have your webcams at the ready for clear nights this month, the later in the night, the better, to ensure it's clear of the horizon murk and into steadier air.

 

Meteor showers, just the Lyrids peaking on the 22nd. Not a big shower.

 

There is a comet, with a complicated name, 73P/Schwassmann-Wachmann, that can be seen, in telescopes, 6 Degrees to the left, east, of Arcturus, at mag 12.  It travels north eastwards and by month's end will end up a degree and a half short of the bottom right star of the Hercules Keystone.  M13 the great Globular, will be just 5 Degrees to the north.  The comet will have brightened to mag 8 by then, and be visible in binoculars.  If you need to know its path I can send you a chart of its position each night.  A couple of interesting points about this comet, it's brightness is due to its proximity (about the closest comet to Earth), rather than because of its albedo or size.  It's also progressively breaking up as it passes the Sun each tour.  So it's not just the one piece but a string of pieces.

 

This is the best time of the year to see galaxies as the centre of the Virgo Cluster of Galaxies, which is in Virgo of all places.  There are millions of them but none is visible to the naked eye, as you might expect, all being well beyond our galaxy's borders.  They spread from Leo through Coma Berenices, Canes Venatici and Ursa Major.  Most are faint and not visible unless you use a CCD camera, though there are many that can be seen in telescopes, particularly on the Coma/ Virgo border, where Messier found 16 and another 5 under the belly of Leo.  He found another 9 around Ursa Major.  Many are spirals, but all need long exposure pictures to bring out their beauty.  The largest we know of is M87, an elliptical, in the middle of the Virgo Cluster.  It's about 60 million light years away and estimated to be up to 500 thousand ly across, where our galaxy, the Milky Way, is estimated at 150 thousand.  Whereas the Milky Way is almost flat, M87 is  elliptical so contains more stars, one estimate is 2.7 trillion, whatever that is. The Virgo Cluster is the one to which our Local Group of 30 odd galaxies belongs.  

The Moon

 

 

 

 

Asteroids and Comets

Asteroid and Comet track predictions can be obtained by clicking the link below.  

This opens a new window.   Just close the window to return to this page.  

Asteroid and Comet Tracks

 

Meteor Showers

 

The following meteor showers are observable:

 

The Constellations

It’s now time to say farewell to Orion and Taurus and hello to Leo, Virgo, Coma and their many galaxies.  As an observer more interested in deep sky, rather than planetary observing, it’s my favorite time of year – Messier marathon season and late nights / early morning observing of the numerous spiral and elliptical galaxies, planetary nebula and globular clusters on display. – It’s heaven!

 

For those of you who are more dedicated (or hopeless insomniacs) reading this article, you can once again marvel at the summer triangle in the early hours of an April morning. I unfortunately must confess to being one of few people who have watched Altair rise to complete the triangle – in mid February shortly before sunrise, having not had a minutes sleep all night!!.

 

Bootes

Bootes “The Herdsman” begins to start its climb to the zenith and is dominated by the star Arcturus, the fourth brightest star in the night sky and the brightest north of the celestial equator. Arcturus is of spectral class K1 and is of orange colour shining at magnitude –0.1. Coincidentally due to its distance of approximately 36 light years its absolute magnitude is little different at –0.2 (Absolute magnitude is the brightness a star would have if it were placed at 10 parsecs – 1 parsec is 3.258 light years – hence 10 parsecs is 32.6 light years). Arcturus is one of the easiest stars to locate, simply follow the tail of Ursa Major – it’s the first really bright star you come to. Epsilon Bootes is an excellent double star sometimes referred to as Pulcherrima or “most beautiful”.

There are no prominent deep sky objects in Bootes.

Virgo

Virgo, “The Virgin”, is dominated by Spica and is unmistakable, simply continue the line drawn from the tail of Ursa Major through Arcturus and the next bright star is Spica. Virgo itself forms a prominent “Y” shape below and to the left of Leo.  Spica is the sixteenth brightest star in the heavens and is of apparent magnitude 1.0 having a spectral class of B1, an absolute magnitude of –3.1 and lying at a distance of approximately 210 light years (depending on which reference books you refer to). Spica translates literally in meaning to “Ear of Corn”. 

 

The most famous deep sky object in Virgo has become M104 “The Sombrero Galaxy”, this is a very bright edge on spiral galaxy of magnitude 8.3, the central dust lane is visible in a 12” scope and it is one of the largest galaxies that we know of. The Virgo cluster of galaxies is made up of M49, M58, M59, M60, M84, M86, M87, M89 and M90 all of these galaxies lie in a close grouping between the stars Epsilon and Omicron Virginis.

 

M87 is an absolute monster of a galaxy with an estimated mass of one trillion (1,000,000,000,000) solar masses. This giant elliptical galaxy has an accompaniment of some 4000 globular clusters and is also known as X-ray source Virgo A. It has a supermassive black hole at its centre and there is a very famous photograph of it emitting a gas jet. The gas jet was photographed as early as 1918 by Heber Curtis at the Lick Observatory but it is only in recent times that we have begun to understand what powers this 4000 light year long celestial searchlight.

The other Messier object in Virgo is M61, this lies just below the Virgo cluster but is not a member of it.

 

Corona Borealis

Corona Borealis, “Northern Crown”, lies to the left of Bootes and is in the shape of a semicircle made up of several feint magnitude stars. Alpha Coronae, the star Alphekka is of apparent magnitude 2.2 and lies at a distance of 78 light years, it is some 130 times more luminous than our own Sun. The most interesting star in Corona Borealis is “R” Coronae which forms an equilateral triangle with the stars Gamma and Eta north of the crown. It is a variable star that is rich in carbon and its variability is caused by the ejection of soot into its upper layers (in simplistic terms).

 

There are no deep sky objects of interest in this constellation.

 

Sextans

Sextans, “The Sextant”, lies south of Leo, the stars Alpha and Beta Sextantis both lie more or less exactly on the celestial equator. The only real feature here is the elliptical galaxy NGC 3115 “The Spindle Galaxy”.

 

Hydra

Hydra, “The Watersnake”, trails beneath the constellations of Cancer, Leo and Virgo and it is the largest constellation in the sky since the conversion of Argo Navis – (see the last edition of First Light for details). The only bright star is Alpha Hydrae, Alphard, this has an apparent magnitude 1.98 and is of spectral type K3. The name translates as “Solitary One” this is quite apt, as there are no other bright stars in this region of the sky.

Hydra contains three Messier objects M83 (a face on spiral galaxy), M68 (a globular cluster) and M 48 (an open cluster easily visible in binoculars with a magnitude of 5.8). My favourite object in Hydra is however none of these, it is the planetary nebula NGC3242, this is located just below the star Mu Hydrae and has the well known name of “The Ghost Of Jupiter”. The name is derived from its appearance when viewed even through a small telescope. It is easily observable and is of magnitude 8.6, it is a planetary nebula that will take lots of power, so crank up the magnification and enhance the nebula with an OIII filter to observe it at its best.

 

Coma Berenices

Coma Berenices, “Berenices Hair”, is not known for its stars but for its fine collection of galaxies. It can be located between Beta Leonis (Denebola) and Alpha Bootis (Arcturus); it lies roughly half way between the two. The brightest star is Beta Comae Berenicis with an apparent magnitude of 4.26 although Alpha, Diadem, has a magnitude of 4.32 and Gamma is 4.35 so all are quite similar.  

Coma has a number of Messier objects, M53 a superb magnitude 7.7 globular cluster that will allow you to resolve individual stars with scopes above 8”, this lies at a distance of approximately 60,000 light years. M64 “The Black Eye Galaxy” is a spiral galaxy although the dust lane that gives this galaxy its appearance, and that leads to its name, cannot be observed with anything less than a 10” scope. The other Messier objects are strictly parts of the Virgo cluster that cross over the Virgo / Coma constellation boundary, these are M85, M88, M91, M98, M99 and M100.

 

Canes Venatici

Canes Venatici, “The Hunting Dogs”, is made up of only two obvious stars. Alpha Canum Venaticorum, named by Edmund Halley Cor Caroli, in honour of King Charles I, it translates as Charles’ Heart. Cor Caroli is a double star that has a yellow primary and blue secondary star that are split by 20 arc seconds, the primary is of magnitude 3.2 and the secondary component is of magnitude 5.7 and is easily split and visible in even small telescopes. Beta Canum Venaticorum, Chara, is of magnitude 4.26 and also of note is Gamma Canum Venaticorum that lies approximately one third of the way from Chara towards Mizar or Zeta Ursae Majoris, this is visually one of the reddest stars in the night sky.

M3 is a globular cluster that lies almost on the boundary with Bootes and is of magnitude 6.4 located at a distance of approximately 40000 light years. M51 “The Whirlpool Galaxy” is famous as it was the galaxy that led to Lord Rosse uncovering the true nature of spiral galaxy structure in 1845, it lies close to Alkaid, Eta Ursae Majoris. M51 has an accompanying galaxy NGC 5195 that links up with it, this was easily observable through the 12” LX200 on our recent visit to Wales although it is quite difficult from Doncaster to see any spiral structure at all even in M51. M94 is a spiral galaxy of magnitude 8.2, M106 is a spiral galaxy of magnitude 8.3. The final Messier object is M63 located at a distance of approximately 35 million light years.

 

Libra

Libra “The Scales” is located between Virgo and Scorpius, it used to be part of Scorpius and the link with Scorpius is obvious, its two primary stars Alpha Librae, Zubenelgenubi  (southern claw) and Beta Librae Zubeneschamali (northern claw).

There are no deep sky objects of note in Libra.

 

LEO – THE LION

Leo is one of the few constellations that resemble what they are meant to, the shape of a lion is unmistakable. In mythology Leo represents the lion killed by Hercules as one of his twelve labours.

 Leo, if not already obvious to observers, can be found by using the two “pointers of Ursa Major” in the wrong direction i.e. away from Polaris, Alpha Ursae Minoris.

 Leo is also the radiant of a meteor shower between the 14^th and 20^th November, peaking on the 17^th November. Approximately every 33 years the shower becomes a meteor storm, such as last year, although observers here in the UK didn’t get a very good display due to cloud cover. 

 

This page was updated on 2 April 2006                  Next Page