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Telescope House February Sky Guide

 

Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


It's February - the shortest month.  This year is not a leap year, where an extra day - the 29th - is inserted to counteract the slightly difference between the Earth's rotation and our very human need to subdivide time.

 While February is most definitely still Winter for those in the Northern Hemisphere, residents of this part of the world will defintely notice the increasing hours of daylight, making both mornings and evenings lighter.  Of course, those in the Southern Hemisphere will be experiencing the exact opposite, with increasing hours of darkness - after their Midsummer in December.  

Wherever you find yourself in the world, as ever, there's plenty to see in the skies above us this February.

 

The Solar System

 

The Moon

 

The Moon begins February as a morning object in Sagittarius, sitting a little under 7 degrees to the east of Venus in the same constellation.  As a morning object, rising a little after 3am, the Moon is naturally in the latter part of its monthly cycle and is displaying a very Old Crescent phase of around 10% illumination.  Our natural satellite occults the planet Saturn on the morning of the 2nd.  This occurs from Europe and Africa as both bodies are rising, just before sunrise, so will be a very tricky event to spot - but not absolutely impossible with a telescope, if skies and eastern horizons are clear.  From the UK, the event will be particularly difficult to observe, with Saturn making its reappearance from behind the Moon as it rises, the height from the horizon of both bodies will be particularly low.  Though those based further east will have a better chance of seeing it.

 

The Moon becomes New on the 4th February when it joins the Sun in Capricornus.  This is naturally the best time of the month for Deep Sky observation and astrophotography, as moonlight won’t affect viewing, or images taken of fainter targets.

 

As the month progresses, the New Crescent Moon climbs higher and higher into the sky, presenting those in the northern hemisphere a great opportunity to observe and image it.  We are now entering the phase of the year where the angle of the ecliptic the moon passes through gets steadily steeper (for observers based in mid-northern latitudes, the opposite is the case for those in similar latitudes south), giving greater separation between it and the horizon for the first part of the lunar month.  On the 10th, the 28% illuminated Moon sits about 6 /12 degrees equally below both Mars and Uranus, which are both sitting next door to each other in Pisces and Aries, handily providing a signpost for both worlds.

 

The Moon reaches First Quarter on the 12th when in the Aries/Taurus borders and makes one of its regular monthly jaunts though the Hyades in Taurus in the late evening/early morning of the 13th/14th.  

 

The Moon passing through the Hyades, 13th/14th February.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


Full Moon occurs on the morning of the 19th with the Moon in Leo, making this the least favourable part of the month for Deep Sky observation and imaging with anything other than narrowband filtration.  This is the second so-called “Supermoon” of the year, which occurs when the Moon is closest to our planet.  More accurately titled “Perigee-Syzygy Moon”, this happens when the Moon is at a close approach to Earth on its slightly elongated orbit and appears slightly larger than average in angular size. Although this can occur at any point in the lunar cycle, the more popularist definition of the “Supermoon” happens when the Moon is Full.  At closest approach, the Moon will be 356758km from Earth.  While there’s no general significance to a “Supermoon”, tides can be higher during a Perigee-Syzygy lunar approach to Earth.

 

The Moon will reach Last Quarter on the 26th while in the zodiacal constellation of Scorpius.  As February ends, The Moon sits alongside Jupiter (by just under 8 degrees), in the morning sky, presenting an Old Crescent phase at around 33% illumination.

 

 

 

Mercury

 

Late January found Mercury at Superior Conjunction, behind the Sun, so nothing can really be expected of observations in February until much later in the month.  However, just like the Moon at this time of year, Mercury is rising in the evening in a favourably steep part of the ecliptic form the perspective of northern hemisphere observers, which will increase the planet’s separation from the horizon as the month progresses, leading to some of the most favourable conditions for observing the innermost planet for observers in these parts of the world.

 

By mid-month, Mercury has climbed into Aquarius and is standing over 9 degrees high (from 51 degrees N) at sunset.   The planet is a 5.5 arc second, -1.1 mag target at this point.

 

Mercury reaches greatest eastern elongation on the 27th, when it will sit over 18 degrees from the Sun and attain an angular height of just under 16 degrees from the horizon (again, from 51 degrees N), as the Sun sets.  Although Mercury will have faded to -0.3 mag, the planet has increased its angular size to 7.4% illumination and decreased its phase to 45% illumination - which should be clear in telescopes under reasonable magnification.  This is going to be the best evening showing of Mercury this year, so if you haven’t observed this illusive world, this presents the best chance to do so this year (November’s Mercury Solar transit aside).

 

 Mercury at greatest eastern elongation, 27th February 2019. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


Venus

 

Venus begins February alongside the very Old Crescent Moon and Jupiter in conjunction in Sagittarius.  Standing just over 15 1/2 degrees high in the SSE at sunrise, the planet will be unmistakable at -4.3 magnitude.  Now at a round 45 degrees separation from the Sun, Venus rises in quite a shallow part of the ecliptic from a temperate northern hemispherical perspective, but should be prominent enough to find and observe easily, though those based in the equatorial and southern parts of our planet will experience much greater separation from the horizon and thus much better seeing conditions when observing our nearest planetary neighbour.

 

Venus and Saturn in the morning sky 18th February.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.

 

Mid-month will see Venus having dipped a little in height from the horizon and in magnitude - though at -4.2 mag, the planet will still be very brilliant and easy to spot.  The morning of the 18th sees Venus line up alongside Saturn in very close conjunction.  The two targets are separated by just over a degree, so will be found in the same field of view in low power telescopes and binoculars.  Venus will be 16.8 arc seconds diameter, at this point, as opposed to Saturn’s 15.4 arc second angular width - Saturn’s brightness being hundreds of times less than Venus’ at +0.6 mag.  The two bodies appearing roughly similar sizes, though very different brightnesses gives us some perspective on solar system dynamics and distance.  On this morning Venus will be just under 149 million km from Earth, as opposed to Saturn’s much further distance of 1.6 billion km.

 Venus and Saturn line of sight arrangement, outer solar system view, 18th February.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


By the end of February, Venus will have faded fractionally to -4.1 mag and is now some 41 degrees to the west of the Sun.  It sits just over 11 degrees high in the S

E (from 51 degrees N) as the Sun rises and displays a 77% illuminated 15.7 arc second diameter disk.

 

 

Mars

 

Mars is a very small (6.1 arc second diameter) +0.9 mag target in Pisces as February begins.  Although now of a significant altitude (46 1/2 degrees high at sunset, from 51 degrees N), for those of us in the northern hemisphere, it is a rather poor target and will remain so until the latter half of 2020.  Some of the major surface markings may just reveal themselves under good conditions, using high magnification in larger telescopes, but the best of Mars is now well behind us.  On the evening of the 12th, Mars can be found around a degree to the north of the much fainter Uranus, which should make location the outer world a little easier.  The following day the planet crosses over into Aries.

 

By the end of the month, Mars will have faded a little to +1.2 mag and shrunk further to a tiny 5.3 arc second diameter disk.

 

Jupiter

 

Now re-emerging from late-December’s superior conjunction, the 1st finds Jupiter as a morning object in the non-Zodiacal constellation of Ophiuchus. At -1.9 mag it’s pretty distinctive, sitting not to far westerly of the brighter Venus in the dawn sky, though fairly low for observers in the northern hemisphere. At 33.7 arc seconds diameter, the planet is a healthy size - though it always is, never dropping anything below 29.8 arc second diameter, even at its furthest from us here on Earth. Standing at just under 16 1/2 degrees high in the south at sunrise (from 51 degrees N), Jupiter is not especially well placed for observation for those in mid and higher northern latitudes, but still always worth a look.

 

Mid month sees Jupiter having brightened a tad to -2.0, having increased its angular size to a diameter of 34.9 arc seconds.  It now sits around 16 3/4 degrees high in the south (again, from 51 degrees N) as the sun rises.

 

Jupiter GRS and Io Transit, 6.30 am GMT, 24th February.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


By the end of the month, Jupiter has increased its diameter to 36.1 arc seconds, though doesn’t appear much brighter than its mid-month figure.  

 

 

Saturn

 

The ringed planet is not especially well-placed for observation in the morning sky at the beginning of February, as its angular separation from the Sun is only about 27 degrees, as it continues to re-emerge from early January’s superior conjunction.  Only attaining an altitude of 8 1/2 degrees as the Sun rises (from 51 degrees N), at +0.6 mag it will be. Difficult spot in the dawn sky - especially from higher northern latitudes.  Languishing in the far southern zodiacal constellation of Sagittarius, Saturn will continue to be a challenge to observe for us “northerners” for some time to come.  

 

Mid-month, as previously mentioned, Saturn is joined in conjunction by Venus, reaching closets separation on the 18th when the two will be just over a degree from one another.  The brighter Venus’ presence alongside will make finding Saturn that much easier - though, in truth, both targets will be rather low from mid northern latitudes, so won’t reward the use of high magnification.

 

By the month’s close, Saturn remains much the same - it rises at just before 4am, is still +0.6 mag and stands just under 14 3/4 degrees high in the SSE as the Sun rises.

 

 

Uranus and Neptune

 

The Outer Gas Giants are a bit of a mixed bag as far as observations go this month.  Uranus is still fairly well-placed for evening observations in Pisces, sitting a little to the east of the much brighter Mars in the ecliptic.  As astronomical dusk starts in early February, the planet is still just over 44 degrees in elevation (from 51 degrees N).  At +5.8 mag it is technically a naked eye object, but you would need a very dark site, keen eyesight, plenty of dark adaption and atmospheric co-operation in order to do so.  Binoculars will reveal Uranus fairly easily - if you know where to look.  Which is why having the nearby Mars as a waypoint in this area of sky, not readily known for bright stars, really does help in finding this illusive object.  Mars is 7 1/2 degrees to the west of Uranus on the evening of the 1st.  Uranus is also just under 1 1/2 degrees to the north of the 4th magnitude star Omicron Piscium.  

 

Telescopes at higher magnification will reveal Uranus’ grey-green disk, which is tiny at just 3.5 arc seconds diameter.  The 12th and 13th February sees Mars much closer to Uranus - the two bodies separated by about a degree - so this is really a good time to try and identify the planet.

 

Uranus and Mars, early evening, 13th February.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.


By the end of the month sees Uranus having moved into Aries, still at much the same size and magnification.

 

Neptune is a much more challenging target, beginning February presenting an 8th magnitude, 2.2 arc second diameter disk.  At just above 2 degrees above the horizon at the beginning of astronomical dusk, the evening apparition of the planet is really at an end.  Superior Conjunction with the Sun is only a little over a month away, so Neptune’s observing season is drawing to a close for now.

 

 

 

New Horizons at Ultima Thule

 

Last month we covered the imminent arrival of NASA’s New Horizons deep space probe at the mysterious “Ultima Thule” or 2014/MU69 on January 1st 2019.  As many will doubtlessly have sen, the flyby was a success and the wait now occurs for the data onboard New Horizons to be beamed back to Earth.  The bandwidth of the probe’s broadcast at this distance is painfully slow, but the first images sent back confirms the hypothesis that 2014/MU69 is indeed a contact binary object, looking somewhat akin to a snowman-cum-bowling-pin in space.  As it happened, New Horizon’s rendezvous with Ultima Thule occurred very close to the object’s Superior Conjunction, which occurred on the 7th January, further complicating and truncating transmissions.  As 2014/MU69 and the area of sky in which New Horizons is currently in continues to draw away from the Sun this will increase the useful amount of time that can be spent collecting the spacecraft’s transmissions here own Earth somewhat - but it will be September of 2020 by the time all the data collected during the flyby is finally received.

 

New Horizon's picture of 2014/MU69.  Image credit: NASA, Public Domain.



Comets

 

Comet Wirtanen (46/P) has put on a reasonable show over the past couple of months, but is now fading as it recedes from its closest approach to Earth, which occurred in December 2018.  A resident of Ursa Major for all of the month, 46/P will be reasonably low in the sky at sunset, though once reaching transit point, which it does a little before a quarter to 1am on the 1st, it will be practically overhead for observers in mid-northern latitudes and thus potentially easier to observe.  The comet hasn’t shown much of a tail, as its path away from Earth has truncated this - though the angles between us and the comet are now changing and may reveal a little more.  However, this must be contrasted with the fact that the comet is progressively receiving less and less solar radiation, which feeds the evaporation of the comet’s surface and is the major driver of tail formation.  Regardless of this, it will still be worth seeking out the comet in the month ahead.  Wirtanen will eventually start dipping more rapidly to the south in the sky and fade even more rapidly as it does.  Early to mid-February will be the best time to pick it out with larger binocular and telescopes.

 

Comet Wirtenan's path through Ursa Major, February 2019.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.

 

2018 Y1 (Iwamoto) will pass 0.30 au from the Earth on February 12th - when it will be found close to the star Regulus, Alpha Leonis.  This recently-discovered comet may reach binocular level brightness in early to mid-February, but this is difficult to predict with any accuracy. It seems fairly likely, barring any potential outbursts, that the comet will be at a peak in the 7th-8th magnitude range - meaning it won't be anywhere near a visaul object. The comet will be passing through Virgo during the first part of the month and then rocket through neighbouring Leo, Cancer, Gemini and Auriga, where it will end the month. 

 

Comet Iwamoto's path, February 2019.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com

 


Meteors

 

The early part of the year is a fairly barren one for major meteor showers. There are no major meteor showers in February. 

 

 

Deep Sky Delights in Canis Minor, Gemini and Lynx

 

Lynx, Gemini and Canis Minor.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.

 

Canis Minor, the Little Dog, is a compact constellation, notable for its bright star Procyon, which at +0.34 magnitude, is the 8th brightest star in the sky.  Procyon is notable as one of the nearest stars to our own solar system, sitting some 11.4 light years away - making it our14th closest stellar neighbour.  Procyon is a binary star, whose constituents are the main A star a white main sequence star of spectral type F5 and a companion, B, which is a white dwarf (type DA).  This companion is a very difficult star to observe, but perturbations in observations of A's proper motion gave it away in 1840 - and by 1861 its orbit had been worked out, yet visual confirmation of B had to wait until a little later.  Procyon B was finally observed in 1896 by the Lick 36-Inch Refractor.  It remains a very difficult object to observe, even in large telescopes, as its angular separation with the primary star is so small.  This and the difference in brightness +0.4 mag for A +10.8 mag for B, mean it is rarely seen and requires exceptional conditions to even attempt.  The two stars are currently separated by 3.9 arc seconds, which roughly approximates to 15 AU actual separation - roughly the distance from the Sun to Uranus.

 

Procyon is a compound of the Greek for "preceding the dog" -  the root meaning of this name comes from the fact that this star was observed to rise just before Sirius, in Canis Major and had great significance to ancient observers because of this.  Ancient Arab myth saw the two main stars of both constellations as sisters, the elder of which, Sirius kept over the "river" of the Milky Way, which now runs between them.  The younger of the Sisters, Procyon, was afraid and stayed on the original bank and wept .  It was these tears that fed the celestial river of the Milky Way and eventually drained into the Nile, causing it to flood.  The reappearance of both stars rising in the evening each year precedes this event - and thus the legend was born.  Indeed, Beta Canis Minor, to be found to the NW of Procyon is named Gomeisa. which translates from the Arabic "little teary (or bleary) eyed one" - a literal link to this legend

 

Moving northward into Gemini we come to the twin stars of Castor and Pollux, Alpha and Beta Geminorum, respectively.  Pollux, the Beta star is actually brighter than Castor, the Alpha - and while it has been suggested that when Bayer codified the brightness classification of stars in the 17th century, Castor was the brighter of the two, this is extremely unlikely.  

 

Castor is a fine double star and an easy target in small instruments.  Consisting of two stars, A and B, of +2 and +2.9 mag respectively, Castor's elements are currently widening and are separated by 4.5-5 seconds of arc.  Castor's double nature was discovered in 1678 by Cassini (he of Saturn's ring division fame, amongst many other discoveries) and bears the distinction of being the first gravitationally bound object to be identified beyond the reaches of the Solar System.  Castor A and B's orbit about a mutual gravitational point takes around 467 years to complete, but both stars are also in turn doubles, with much fainter M-class dwarf companions.  In addition to these companions there is also present in the system a further pair of gravitationally bound M-class stars.  This makes Castor not just a double star, but a sextuple - quite a collection!  Sadly, only the primary elements are observable in amateur instruments.

 

To the westerly reaches of Gemini, is to be found M35.  M35 is a very prominent star cluster, at +5 mag, easily picked in small telescopes and binoculars and can also be seen with the naked eye from a reasonable site.  Consisting of well in excess of 100 observable stars (mags 6-13th), M35 was first noted by Astronomer Philippe Loys de Cheseaux in 1745.  Also included in the Uranographica Britannica by John Bevis in 1750, M35 was catalogued by Messier in 1764, who credited Bevis with its discovery.

 

Many of the 100+ observable stars are types G and K stars - similar in class to our Sun - though these seem to be of a considerably larger mean size than main sequence.  M35 is tentatively aged at about 100 million years - about the age of the nearby M45, (the Pleiades) though problematically, stellar evolution is thought to be considerably more advanced in the case of M35.  Does this mean that M35 is in fact older, or are the Pleiades actually younger?  Further observation and theories will be needed to explain this anomaly.   

 

In the background sky to M35 lies the fainter (+8 mag) open cluster NGC2158, though this is nearly six times further away than M35's 2800 light years. In addition to this, there is also the yet fainter and more compact IC2157 cluster (+8.4 mag) - making this an extremely rich area for sweeping with virtually any type of optical aid.

 

M35 & NGC2158.  Image credit: Mark Blundell

 

Drifting eastward, 2 1/3 degrees east of the star Wasat (Delta Geminorum) is the fabulous Eskimo Nebula, NGC2392.  This Planetary Nebula supposedly resembles an Eskimo's head, surrounded by the fur of an Arctic Parka hood.  A reasonably compact 0.8 arc minute across (about 2/3rds the size of the Ring Nebula, M57), the Eskimo is only +9.19 mag, though its compact size makes its surface brightness quite high and it takes magnification well.   Discovered by William Herschel in 1787, it is perhaps surprising that it wasn't noticed by earlier observers - though this is most likely down to its small size.  OIII filters reveal more of the two stages of the object: it's tenuous outer shell and the gleaming, brighter interior.  Larger instruments reveal more of the complex structure of the internal part of the Eskimo -  its radial double shell of expanding gasses and fine s blown by cosmic winds form its central star.  This central star shines at +10.5 mag and is relatively easy to spot in most instruments.   The nebula is thought to lie at 2800-3000 light years distance.

 

The Eskimo Nebula, Hubble Image.  Image Credit: NASA/ESA.  Public Domain.


Further south from the Eskimo is another older, larger and fainter object - The Medusa Nebula (Abel 21).  Whereas the Eskimo is small and comparatively bright, the Medusa is large - at 10 arc minutes across it is a third the diameter of the Full Moon.  Telescopes of 8-inches + aperture, coupled with a good OIII filter and a dark site will be needed to seen the Medusa.  Although listed as being +10.19 mag, this is spread out over a significant area of sky, so it is in long duration astrophotography that the wonders of the Medusa really start to reveal themselves.  A modest aperture telescope will be needed and a sturdy equatorial mount, capable of being autoguided , will be needed to attempt to image this object.  Images reveal the serpent-like tendrils of nebulosity that give this mysterious object its name - its namesake Medusa being the Gorgon who had snakes for hair in classical Greek mythology.  The stare of Medusa was reputed to turn people to stone, though staring at this nebula through a large telescope will be a much more pleasant experience…  The Medusa lies about half the distance from us as the Eskimo Nebula - 1500 light years and is around 4 light years in diameter.  Opinions were divided on the true nature of the Medusa: George Abel, its discoverer thought it to be an old planetary nebula, whereas many considered its irregular nature to indicate it was a supernova remnant.  Narrowband imaging has revealed the true extent of the Medusa's helical hourglass figure - making it much more likely to be, as Abel initially suggested, a planetary nebula.

 

The Medula Nebula.  Image Credit: Joel Schuman, Mt Lemmon Observatory, Creative Commons.


Drifting northward, we come to the large, sparce constellation of Lynx. which contains a couple of interesting objects for Deep Sky enthusiasts.

 

The first object of note is NGC2419, the Intergalactic Wanderer, a rather dim globular cluster, which lies some way away from the regular haunt of the globular - the shell around the central part of the Milky Way.  The Intergalactic Wanderer was nicknamed as such, due to the fact it used to be thought as an extra-galactic cluster, wandering through space.  Observations of its motion have revealed it is not - it is indeed a satellite of our galaxy, much as the other major globulars are - in NGC2419's  case just a very outlying one.  At 270,000-300,000 light years from us, it is almost twice as distant as the Large Magellanic Cloud, but intrinsically very luminous.  It almost matches the King of Globular clusters, Omega Centauri, for true brightness, but appears as a rather feeble +10 mag object at just 1.8 arc minutes across, simply because it is so far away.  Larger telescopes will be needed to see much of it, though it is possible to pick out in smaller instruments from dark locations.

 

The Intergalactic Wanderer, NGC2419. Image Credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona - Caelum Observatory Creative Commons


Lynx, whilst obscure to the naked eye observer, also contains a couple of galaxies of note, NGC2537, otherwise known as the Bear Paw Galaxy and NGC2683, The UFO Galaxy.  

 

The Bear Paw is a barred spiral is located roughly in the centre of Lynx, 9 1/2 degrees to the north of the Intergalactic Wanderer and some 14 3/4 degrees to the NW of NGC2683 - giving a good idea how large Lynx is as a constellation.  The Bear Paw is a very compact object, being some 1.7 x1.5 minutes of arc across - and although officially classed as a +11.69 mag object has a high surface brightness because of its diminutive area and is rather more visible than many objects of similar listed magnitude.  The Bear Paw is so-called due to the areas of brightness which form a patchy pattern, which somewhat resemble the paw print of an animal.  Whether it is that of a Bear or not, we leave you to draw your own conclusions... NGC2537 is thought to lie some 22 million light years away from our own Milky Way Galaxy.

 

 The Bear Paw Galaxy, NGC2537.  Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.

 

Discovered in 1788 by William Herschel, NGC2683, otherwise know as the UFO Galaxy (for obvious reasons), is a spectacular object which lies almost edge on to our line of sight on Earth and subsequently has a very reasonable surface brightness.  Covering an area of sky 9.3 x 2.1 arc minutes, NGC2683 is easily seen in large telescopes, whereas smaller scopes will just resolve its bright elongated core.  The foreshortened spiral arms of the UFO galaxy are laced with dust lanes, one of the major examples of this practically bisects the core from our perspective.

 

The UFO Galaxy, NGC2683. Image Credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona - Caelum Observatory Creative Commons


It is thought that NGC2683 is reasonably close to the Milky Way group, from a cosmic perspective, though different sources list its distance as a widely variable 16-33 million light years away.  The UFO Galaxy's core is often remarked upon as appearing yellow - indeed, it seems that there are a larger population of older yellow and red stars in this galaxy than average and that there is little star-forming activity taking place within the system.  Compared to our galaxy, though less massive and luminous, NGC2683 boasts twice the number of globular clusters.

 

Text: Kerin Smith