February 2020
Sky Notes
Sky Map for 15th February 22:00 -  Courtesy of Heavens Above
The Planets
Mercury Setting 70 mins after the sun.
Venus Good evening Planet setting approximately 4 hours after the sun.
Mars Now a morning Planet only 4 arcseconds in size.  Rising a couple of hours before the sun.
Jupiter A morning object near to the sun.  Please note Jupiter is very close to the Sun, so take care if you decide to view using binoculars, telescope or mark1 eyeball.
Saturn Not visible this month
Uranus Evening Planet, losing altitude by the end of the month.
Neptune Evening planet best viewed at the beginning of the month.
First Quarter 2nd of the month
Full Moon 9th of the month. Supermoon but don’t get too excited.
Third Quarter 15th of the month
New Moon 23rd of the month

For more detail re the Planets for January, goto Allan Clitherow’s Planetary Notes on our website.
January's Monthly Challenge

Let’s look for a star cluster this month.
M46 (NGC 2437) is an Open Cluster lying almost halfway between Sirius and Alphard to its east.  As it is quite low in the sky, this will be a difficult challenge.  This Cluster is also known as the Little Sisters and when you find it, you will see why.
Jim Barber

Director of Observations
Dundee Astronomical Society
Ken’s February Moon Notes

From the point of view of the Moon, the month starts with a bang - well, it starts with the Moon at an age of 7.9 days on 1st February at 1800UT.  Now this is a good phase for so many features on the Moon and with spring approaching (hopefully) the Moon phases near to first quarter are gaining a reasonable elevation.  On the 1st, the Moon transits at about 1800 UT at an elevation of 39.5º.

Let’s have a look along the terminator, starting close to the north pole.  The libration on that date is +6º but at that phase, the craters Byrd and Peary which I previously mentioned will not be very well illuminated, but the area would be worth having a look at to see if you can see the eastern rims of them.  Move southwards to get a good view of Vallis Alpes which will be close to the terminator.  The bottom of the graben valley will be in shadow so it’s unlikely that you will be able to see the sinuous rille running along the flat, basalt filled valley.  It is difficult enough to see anyway and only with a moderate sized telescope in steady seeing conditions.  Move southwards again and leaving the more rugged Montes Alpes into the flatter Mare Imbrium, the isolated peak, Mons Piton, has just seen sunrise and will stand out brightly with a fine elongated shadow.  Southwards again by a short distance and the two craters which will stand out, close to the terminator, are Aristillus (more northerly) and Autolycus, 55km and 39km respectively.  Aristillus has the more obvious central peak mass but both craters, in particular Aristillus, have interesting and relatively symmetrical ejecta blankets - it is interesting to compare the ejecta blankets with that of Archimedes when it emerges into daylight by the next evening.

Southwards moving from Mare Imbrium over Montes Apenninus you will see to the east, a little way in from the terminator, the often-mentioned Rima Hyginus dogleg rille.  A short distance south is the smaller crater Triesnecker (26km) but what to look for is the network of rilles, especially on the crater’s eastern side. These rilles are not sinuous but probably the result of tectonic forces, i.e. they are genuine ‘cracks’ in the Moon’s surface.

Further south are three large craters emerging from shadow.  The most northerly is Ptolemaeus (154km) which has a low irregular rim but is fundamentally circular and with a flat basaltic interior. No central peaks can be seen, and one has to assume they were covered by subsequent lava flows.  There are a few small craters in the floor of Ptolemaeus and ghost craters have been reported, but these will only be seen with a perfect elevation of the Sun and a large telescope. Ptolemaeus adjoins the crater Alphonsus (119km) to the north and a rugged boundary wall divides the craters.  Like Ptolemaeus, Alphonsus has a roughly circular outline bounded by quite low and irregular walls.  The floor of Alphonsus is basaltic but there is a single central peak. A low ridge cuts north - south across the floor of the crater and there is an extensive system of rilles but these will not be seen on the 1st as the terminator will still lie across the crater. Finally, just south of Alphonsus is the crater Arzachel (96km).  Arzachel is relatively young compared to the other two and is more regular with terraced walls.  There is a rugged central peak which is rather offset from centre towards the west with a small crater to the east of the peak. With the right lighting and seeing conditions, a rille system can be identified and the terracing and rilles make this crater worth a closer look the following evening.

There is a huge amount to see at this phase and what I have pointed out will probably be sufficient to keep a lunar observer interested for quite some time.  The features mentioned will also be worth a look on the following evening as lighting for some may be better, and it’s always useful to look at any feature for a few nights to compare what is seen in the changing elevation of the Sun.

The map I have provided this month for the 1st February simply indicates the position of the objects mentioned as they are too widely distributed to produce individual detailed illustrations.  As always, south is towards the top.

If you find that the Moon starts to interest you, it would be worth getting a lunar atlas.  There are a few good software programmes but also DAS has a few lunar atlases which came from Tom Lloyd-Evan’s book collection and could be borrowed if you contact the librarian.  The book of choice as an atlas is that of Antonín Rükl which had a final edition printed in 2007.  Rülk died in 2016 and as far as I know, it has not been reprinted.  Copies are available online but those I have seen are quite expensive now.

Ken Kennedy
Jim’s Focus of the Month

Realm of Galaxies.
To find this region of the sky, find the Constellation Leo the Lion, go east at the fear end of Leo and you are in the Realm of Galaxies.
This area is reputed to have around 2000 elliptical and spiral Galaxies, of which approximately 20 are visible to the Amateur Astronomer using a medium telescope.  Some of the exciting objects to view are M64 the Black Eye Spiral Galaxy, M86, M87, and M88 a Spiral Galaxy.
Providing the Skies cooperate, just navigate to that area and enjoy.
Sadly, news reached us that Dr David Gavine a lifelong member and Honorary President of our Society passed away on the 2nd of January.  Dave will be greatly missed by all who knew him.

Let’s look forward to February and see what is in the skies.

Early in the morning of the 26th, Callisto will be transiting Jupiter and casting its shadow on the planet.   As the transit is happening between 06:30 and 09:38 UT this is going to look faint but within our ability to view it.  Have a go, it should be quite exciting.  Also, there are three planets in a line at this time with Jupiter in the middle, Saturn to the East and slightly below, whilst Mars to the West and slightly above.

We all know about the Summer Triangle, but what about the Winter Triangle?  The Winter Triangle is formed by Betelgeuse (Orion), to the east Procyon in (Canis Minor) and below, Sirius (Canis Major). At this time of year, the Milky Way passes through the Triangle and it is well worth having a go at imaging.  Almost halfway between Sirius and Procyon is M50 (NGC2323) the Heart shaped Cluster.  At Mag 5.9 it should easily seen in binoculars and small telescopes.  There are many riches to see in Monoceros such as the Rosette Nebula, the Cone Nebula, well worth scanning your telescope through.

Talking about Orion, Betelgeuse has been dimming and it is quite evident that it is not as bright as it has been lately.  Don’t be too alarmed as it has done this several times in the past and normally returns to normal after a period so don’t get too worried.