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Telescope House March Sky Guide

Telescope House March Sky Guide 

 

This month, we prepare ourselves for the return of Springtime, which occurs in the latter part of March for those in the northern hemisphere - and we can only hope that things improve, weather-wise.  Those readers in the southern hemisphere will enter Autumn at the same time - we wish you well too!

 March 20th 2018 represents the boundary were the Sun crosses the Celestial Equator into the northern half of the Ecliptic.  Gradually, after this point in the year, days for those resident in the Northern Hemisphere begin to get longer than the nights and conversely, for those in the Southern Hemisphere, the opposite is true.  This point in March is known as the Vernal Equinox, from the Latin word of Spring - "Ver".  Days and nights during this time are of a roughly equal length, but beyond the Vernal Equinox, those of us in the Northern Hemisphere begin to lose those precious hours of darkness. Daylight starts to win out in the cycle of day and night, in the downhill slope towards Summer.  At the end of March and beginning of April, those countries around the world which operate Daylight Savings begin to change their clocks forward, if they are entering Springtime, or back if they are entering Autumn.  This naturally influences the spread of hours of darkness and light yet further.

 However, wherever you find yourself in the world, this time of year presents some of the most rewarding opportunities for observation - so if there's clear weather, get out there and have a look, as ever, there’s a lot to see in the skies above…

 

The Solar System

 

The Moon

 

The Moon starts March in Leo, just shy of Full and reaches Full on the 2nd, when on the Leo/Virgo borders. Being Full Moon, naturally, this is not the best time for deep sky observations, or imaging faint objects without significantly narrowband filtration.

 

The Moon reaches Last Quarter on the 9th, while residing in Ophiuchus and can be found around 3 1/2 degrees NE of Mars in the earlier morning sky. 

 

The Moon reaches New as it joins the Sun on the Pisces/Aquarius borders on the 17th, after which it becomes an evening target. The following evening, it may be possible to pick out the tiny sliver of the very slim Crescent Moon strung out in a line alongside Mercury and Venus, just after sundown. 

 

The Moon then begins rising through a very steep part of the ecliptic from a temperate northern hemisphere perspective, gaining altitude night by night as it moves through the constellations of Cetus, Aries and Taurus, until it reaches First Quarter high in the northern ecliptic in Gemini on the 24th. This is one of the "High Spring Crescents" for which this time of year is notable and provides excellent opportunities for observation and imaging from temperate northern climes. Winding back a couple of days and the 5 day old Crescent Moon occults the Hyades in Taurus on the evening of the 22nd.  Unfortunately, the Moon will be set over Europe by the time it occults Aldebaran - but look out for this event, as it’s always a lovely sight, even when viewed with the naked eye.

 

The Moon occults the Hyades, March 22nd.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


The Moon ends March in Virgo in fine style with another Full Moon - the second "Blue Moon" of 2017. The term Blue Moon has nothing to do with the Moon's colour. It is thought to be a corruption of the archaic English word "belewe" which means to betray. The reasoning behind this is that two Full Moons in one calendar month "betrays" the regular monthly lunar cycle - hence the term "Belewe Moon”.

 

Mercury

 

Mercury starts the month as an evening target, sitting just over 10 1/2 degrees from the Sun in Aquarius. It is reasonably well-placed for temperate northern hemisphere observations at the month's beginning. Mercury stands just under 8 degrees high at sunset (from 51 degrees N), which will make observations practical from most parts of the world - though observers are aided in their attempts to locate Mercury by the much brighter Venus, which sits a degree and a half to the NW on the 1st. At -1.3 mag and 5.4 arc seconds diameter), Mercury is around as bright as it's possible to get, but as ever, it's proximity to the Sun makes it an observational challenge. Venus and Mercury stay in conjunction for much of the first week of March, reaching their closest point on the 4th when they will be just over a degree from on another. 

 

Mercury and Venus in conjunction, March 4th.   Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

By mid-month, Mercury reaches its greatest eastern elongation from the Sun, the two being separated by around 18 1/3 degrees. This represents one of the best opportunities all year to observe the innermost planet, as it stands just under 16 1/4 degrees high at sunset (from latitude 51 degrees N). Although by this point, Mercury's phase has shrunk to 44% illumination, which lowers its brightness to -0.2 mag. Venus will still provide a useful guide to its fainter neighbour's location, as it can be found just over four degrees lower in the sky as the Sun sets. 

 

Beyond mid-March, Mercury appears to fall back towards the Sun rapidly (from our perspective on Earth) and will fade substantially as it draws nearer to us on its interior orbit, although it does grow significantly in size as this occurs. Unlike Venus, Mercury's brightness in these circumstances doesn't remain static - it is a much smaller, less reflective (and intrinsically fainter) world than its larger neighbour and significantly further away from us in the solar system. 

 

By the end of the month, Mercury is a day off inferior conjunction with the Sun, sitting between us and our parent star. After this, it will reemerge on the morning side of the Sun. 

 

Venus

 

At the beginning of the month, Venus is an evening target, found in Aquarius at -3.9 mag, showing a 10 arc second diameter, 98% illuminated disk. The planet is creeping north in the ecliptic and now stands over 9 degrees high at sunset (from latitude 51 degrees N). The planet is separated from the Sun by 12 1/2 degrees. On the evenings of the 2nd-5th March, Venus and Mercury are in close conjunction with one another, separated by 1 to 1 1/2 degrees. Using the bright Venus as a guide, to the location of the fainter Mercury, will make locating the innermost planet a relatively easy task. 

 

By mid-March, Venus has increased its separation from the Sun to just under 16 degrees, but only stands a little higher at sunset - 12 1/2 degrees (from latitude 51 degrees N). The planet is no brighter at -3.9 mag. 

 

By the end of the month, Venus has crossed over the border into Pisces. On the evening of the 28th, it will be in very close conjunction with Uranus, providing another handy signpost to a fainter planet's location. The two are separated by around a quarter of a degree as they set from Europe. However, it may be very tricky to spot Uranus, as astronomical twilight will still be upon us as the two worlds set. This, coupled with atmospheric extinction, will make observations of the event difficult, but not impossible. If the weather is kind and your westerly horizon is clear, why not try to see these two very different worlds in the same field of view of a telescope or binoculars?

 

Venus and Uranus in conjunction (blue ring represents a 0.5 degree field of view).   Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

Venus ends the month, in Aries, at -3.9 mag, separated from the horizon by just over 16 degrees. Venus presents a 10.6 arc second, 94% illuminated disk. 

 

Mars

 

At the beginning of the month, Mars is now found in Ophiuchus at a steady, if unspectacular, +0.8 mag. It is 6.7 arc seconds in angular diameter and the Red Planet stands just under 16 degrees high, almost due south at daybreak (from latitude 51 degrees N).

 

On the morning of the 10th, Mars is joined in loose conjunction by the very old crescent Moon, the two being separated by just under 4 degrees. 

 

Mars and the Moon, sunrise, March 10th.   Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

By mid-month, the +0.6 mag Mars has crossed over into Sagittarius and stands just over 15 degrees high in the south at sunrise (from latitude 51 degrees N). The planet now rises at around 2.30am and transits a little after 6.20am (GMT). 

 

At the end of March, Mars can still be found in Sagittarius and now shines at +0.3 mag, standing just under 15 degrees high in the south at sunrise (from latitude 51 degrees N). In many parts of the world, particularly the northern hemisphere's temperate regions, various countries choose the end of March to change to Daylight Saving Time, which briefly appears to make rising times later (Mars will rise around 3.07am BST on the 31st).  However, despite this human-induced change, the trend as far as Mars is concerned is towards earlier and earlier rising as the planet heads towards opposition in July. 

 

Jupiter

 

The beginning of March finds Jupiter at -2.2 mag in Libra. The planet rises at 12.18am (GMT) and transits at 4.49am, when it will attain a height of just over 21 degrees in the south (from 51 degrees N).

 

Jupiter GRS and Europ transit, 1.19am, March 3rd.   Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

Mid-month sees Jupiter having begun its annual period of retrograde motion in the ecliptic - appearing to move east to west, rather than the usual west to east again the background stars. This retrograde motion will last until mid-July, Jovian opposition falling neatly half way through this period on May 9th. 

 

The 15th finds Jupiter at -2.3 magnitude and 40.8 arc seconds across. Jupiter transits at a little before 4am, when it stands just over 21 1/4 degrees high in the south (from 51 degrees N). 

 

March 31st finds Jupiter in Libra at -2.4 mag, 42.5 arc seconds diameter and standing 21 1/2 degrees high at transit point, which it reaches at 3.48am (BST) - the change in time from standard to daylight saving in Europe having occurred on the 25th March (and earlier in the month for those observers in North America). The planet will have risen after 11.15pm local time the preceding evening (from 51 degrees N). 

  

Saturn

 

Saturn is a morning target in Sagittarius during March, rising at a little after 3.56am (GMT, from 51 degrees N) and stands 14 2/3 degrees high in the S at sunrise. At +0.6 mag, Saturn isn't especially prominent, but still brighter than any star in its resident constellation. It is separated from the Sun by just over 63 1/4 degrees on the 1st. 

 

By the end of the month, nothing much has changed as far as Saturn's concerned: the planet has brightened a little to +0.5 mag and is now 15.9 arc seconds across. The planet now stands just over 16 degrees high at sunrise (from 51 degrees N), having risen at just past 3am (BST). It can be found a shade under 1 3/4 degrees to the NE of the brighter Mars on the 31st, which it will be in even closer conjunction with in early April. 

 

Uranus and Neptune

 

Neptune reaches superior conjunction on March 4th (after which it reemerges as a morning object), and as a consequence, is lost to potential observation during much of the month. 

 

Neptune at superior conjunction, March 4th.   Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

Uranus is somewhat better placed at the beginning of the month, but it too is approaching superior conjunction in mid-April. At +5.9 magnitude and 3.4 arc seconds diameter at the beginning of the month it won't be hard to find in the central "V" of Pisces, setting a little before 10pm on the 1st (GMT, from 51 degrees N). However, fast forward to the end of the month and the situation changes radically. As previously mentioned, on the evening of the 28th, Venus and Uranus are in close conjunction - separated by around a quarter of a degree after sundown. However, the challenge will be to pick the much fainter Uranus out in the evening twilight, before the onset of true astronomical darkness and atmospheric extinction renders the setting planet invisible. 

 

Uranus' position, sunset, March 15th.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 

Uranus ends March just under 16 1/2 degrees from the Sun. 

 

Comets

 

There are no reasonably bright comets predicted to be observable during March (at time of writing).  However, we have the distinct probability of three naked eye comets during 2018 - the recently discovered comet Pan STARRS 2017 S3, which should reach a peak in August/September, and the return of periodic comets 21P/Giacobini-Zinner (which could reach mag 4 in August/September) and 46/P Wirtanen (which is due to reach low naked eye visibility in the latter part of the year, peaking in December for those in the northern hemisphere).  As ever, there’s always the chance of new comets being discovered, or know ones having outbursts of brightness.  We’ll naturally keep you posted in regards to future developments we receive them.

 

 

Deep Sky Delights - The Messier Marathon

 

We take a break from our regular round up of in-depth coverage of observations of the extra-solar system kind, to cover the grand tour-de-horizon that is the Messier Marathon.  Many readers will have heard of this challenge - to observe as many, if not all of the 110 deep sky objects on the Messier list in one night's sitting.  Around the Vernal or Autumnal Equinoxes is normally the most sensible time attempt the Marathon, as the spread of Messier objects in the sky, the chance of clearer weather and a significant amount of darkness all conspire to give us the best chance of picking off the majority - if not all of the Messier list.  The March’s New Moon on the 17th presents a good opportunity to try to pick off as many members of the list as possible, during the evening of the 17th and the early morning of the 18th - although the following New Moon of April 16th also presents a reasonable opportunity as well.

 

It must be noted that the Marathon is not possible everywhere in the world.  Charles Messier, making his observations from France in the 18th century, did not have the opportunity to add many of the wonderful deep sky treasures of the southern hemisphere to his list, and a significant amount of Messier objects are circumpolar for those in the northern hemisphere - which put southern hemisphere observers at a distinct disadvantage!

 

The optimum latitude for attempting the Messier Marathon is about 25 degrees N, but this should not put those who are further north or south of this part of the world off attempting it.  You will simply have to complete the Marathon with what's practical to observe from your particular location. 

 

So, what do you need?  

 

1. A Telescope.  While it's possible to observe many of the Messier list in binoculars, the type of magnifications needed to resolve some of the fainter members of the list really do require a telescope to be sure of identification.   Naturally, the larger your aperture, the better your chances of positively identifying some of the fainter members of the Messier list and a Goto telescope will help immeasurably - though some observers will regard this as cheating somewhat.  However, in regards to a telescope's aperture, it should be noted that Messier himself observed with many telescopes throughout his career, but made many of his discoveries using a refractor of around 3-4 inches / 90-102mm of aperture, or a Gregorian reflecting telescope of around 7.5 inches of aperture. Both instruments would have been roughly equivalent in performance to many general starter's telescopes today, albeit they were used in the 18th century, when skies were generally much darker than they are today.  

 

2. A Dark Observing Site. As eluded to above, dark skies are essential to achieving positive identification of some of the fainter members of the list.  The absence of the Moon from proceedings is also extremely helpful, as any additional skyglow caused by our natural satellite will be extremely unhelpful.  This makes the New Moon period of the 17th March a more favourable time to observe, but a couple of days either side of this date should be good too, with a thin Crescent phase Moon not adding too much to the illumination of the sky.

 

3. Clear Horizons.  The early evening's window of observing objects in the extreme west of the sky will require a clear westerly horizon in order to have any chance of seeing these targets.  This year favours an earlier Marathon attempt for practical reasons: for instance, around 16th April, the galaxy M74, one of the most beautiful face on spirals in the sky, but unfortunately the Messier object with the lowest combined surface brightness will only be 5° 24 minutes from the setting Sun, making it impossible to detect.  On the 17th March it is a much healthier 30 degrees + separation form our parent star, making detection still a challenge, put all the more likely.  Likewise, M30 in Capricornus won't have risen very high in the sky by sunrise, so will be a difficult find in the dawn sky at the end of the night.  Likewise the wonderful open clusters M6 and M7 in Scorpius and the Globular clusters M54, M55, M69 and M70 are very low and difficult to detect in the morning sky from mid-northern latitudes.

 

4. Patience and Tenacity.  This is a Marathon and not a sprint!   Not everything on the list may be observable in one sitting, but the challenge is to observe as much as you can. Special attention should be paid to pacing yourself, making sure you're properly dark adapted, insulated from the cold of a springtime night and hydrated and fuelled as well. If you're not paying attention to all of these criteria, you run the risk of fatigue, which will ultimately make the Marathon a slog - when it's meant to be enjoyable.

 

When attempting the Messier Marathon at this time of year, we can split it up into roughly four quarters.  The first of these are those objects that are in the west of the sky after Sunset, which need to be observed quickly before they set (or become too low to observe in the north).  If you use the Milky way as a dividing line, these are all the Messier objects that fall to the West of this point.  This section of sky includes some of the brightest and best known of the Messier list:  M31, the Andromeda Galaxy and its two attendants M32 and M110; M33 the Triangulum Spiral (which will be a tricky target in the evening at this time of year, due to its low surface brightness); the wonderful Pleiades (M45) and M1, the Crab Nebula in Taurus and of course the Orion Nebula complex, M42 and M43.  While these targets are pretty easy to find, special attention should be shown to those potentially difficult objects in the southern reaches of this sector, such as the globular M79 in Lepus, which will be set by just past 9pm from mid-northern latitudes.  It is also a good idea to attempt to observe the circumpolar Messier targets in the low NNW, such as the open cluster M39 in Cygnus and the easier, higher up targets in Cassiopeia and Perseus, if possible, though there will be opportunities to observe these later, if this is not practical.

 

First quarter of the Messier Marathon, looking west after sunset, March 17th.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

The second quarter of the Marathon is the most populous in terms of extra-galactic Messier objects This area of sky is the swathe east of the Milky Way, which takes in the huge arc of galaxies which runs from the fantastic pairing of M81 and M82 in the northern reaches of Ursa Major, down through multiple galaxies in Canes Venatici, Coma Berenices down into the huge riches of VIrgo and Leo, ending south of the celestial equator with the challenge of M104, the Sombrero Galaxy on the Virgo-Corvus borders.  This area takes in just over a third (36) of the Messier List and will take the longest time to work through.  Naturally a Goto telescope will help considerably  here, as many of the objets in this part of the sky are towards the fainter end of Messier's list and tricky to find and positively identify for the uninitiated.  Amongst the profusion of galaxies, there are notable globular clusters in the guise of the magnificent M3 in Canes Venatici and M53 in Coma Berenices, the intriguing Owl Nebula, M97 - the "companion" of the galaxy M108, both of which are found near Merak, Beta Ursae Majoris.  There is also the strange M40, which appears to have been catalogued, despite being simply a double star in Ursa Major.

 

Second quarter of the Messier Marathon, looking north through south, midnight, March 18th.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

Where the second quarter of the Marathon was largely taken up by galaxies, the third quarter is very much the preserve of nebulae and star clusters - particularly the globulars which orbit the central bulge of the Milky Way.  This quarter will have to wait until well after midnight in order to risen high enough for observation and contains the riches of Ophiuchus, Scorpius and Sagittarius - to west of the "Summer" part of the Milky Way, which looks directly towards of galactic centre and the richest area of deep sky objects bounded by our galaxy.  In addition to the area, there are also the more northerly targets in Serpens (Caput), Hercules, Lyra and the Western half of Cygnus.  This is a really challenging part of the marathon, as many of the targets will be very far south from mid-northern latitudes and atmospheric extinction will play a large part in observations.  Highlights in this area include the great globular clusters of M13 and M92 in Hercules, M5 in Serpens, M10, M12, M14 and M07 in Ophiuchus and, if observable, M80 and M4 in Scorpius.  However, you may have to revisit the latter two objects later in the night to see them well, if at all.

 

Third quarter of the Messier Marathon, looking SE at 4am, March 18th.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

The last quarter of the Messier Marathon really is a race to see as much as is possible before the Sun begins to rise and Astronomical Dawn begins, which for many mid northern hemisphere latitudes is just after 4am at this time of year.  This area of sky includes the eastern side of the "Summer" section of the Milky Way from the eastern side of Sagittarius in the south, up through Sagitta, Vulpecula and the eastern side of Cygnus, on through to the star clusters in Cassiopeia in the north.  This area also includes the great globular clusters M15 in Pegasus and M2, below it in Aquarius.  This area inevitably includes some of the toughest fainter objects to attempt to see before the dawn breaks - notably the fainter globulars M72 and M75 and the rather disappointing asterism M73, all in Aquarius.  These will be extremely tough, if not impossible to see from higher northern latitude before the Sun makes its presence felt.  However, this part of the night gives observers in higher northern latitudes the best chance of seeing the great areas of nebulosity in Sagittarius, M8 the Lagoon Nebula, M20 the Triffid Nebula, M17 the Omega Nebula and the Eagle Nebula in neighbouring Serpens at reasonable altitude.    

 

Last quarter of the Messier Marathon, looking east at 5am March 18th.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

When you consider the possibility of seeing the lion's share of the Messier list in one sitting, it is perhaps wise to consider that it took Messier, aided by the excellent contemporary observer Pierre Mechain and reference to the observations of other earlier telescopic astronomers such as Giovanni Battista Hodierna, over a decade to expand his initial list of 45 objects, published in 1771, to the 102 objects of his final list, which was published in 1781.  With reference to Messier's observing notes, this final list was expanded to the 110 objects we know today, by Messier scholars in the 20th century.  If it took Messier, a professional astronomer, this long to be sure of his observations, then don't be too disappointed if you can't see all of the Messier list in one night, should you attempt the Marathon.  If you do attempt this epic task, we hope the weather is kind to you and however many objects you find, you enjoy it.

 

Text: Kerin Smith