The Night Sky January 2017


Compiled by Ian Morison


This page, updated monthly, will let you know some of the things that you can look out for in the night sky.  It lists the phases of the Moon, where you will see the naked-eye planets and describes some of the prominent constellations in the night sky during the month.


New

The author's: Astronomy Digest

which, over time, will provide useful and, I hope, interesting articles for all amateur astronomers.   A further aim is to update and add new material to link with the books recently published by Cambridge University Press.

January 2017: All About Refractors Part 1: Their objective Lenses.

                        The Direct Detection of Gravitational Waves - to update 'A Journey Through the Universe' and which gives a concise account of                     what must be one of the most significant discoveries of recent times.

Cambridge University Press has recently published two books by the author. An Amateurs Guide to Observing and Imaging the Heavens is a handbook aimed to bridge the gap between the beginner's books on amateur astronomy and the books which cover a single topic in great detail.   Stephen James O'Meara and Damian Peach have both given it excellent reviews. 'A Journey through the Universe' outlines our current understanding of the Universe and was based on the lectures I gave as Gresham Professor of Astronomy.   Martin Rees has written a very nice review of it.


Image of the Month

Pleiades

An Asteroid in the Pleaides Cluster

Image: Ian Morison

This image of the Pleiades Cluster was taken with an 80mm aperture telescope and shows the nebulosity surrounding the cluster stars quite nicely.   The nebulosity's colour is blue as the dust particles (within the dust cloud that the cluster is passing through) preferentially scatter blue light.   The streaks are due to magnetic dust particles (hence containing iron) lining up along the rather chaotic galactic magnetic field.   The Pleaides Cluster lies at a distance of ~440 light years and contains several hundred stars.

 In one 137 minute imaging session (of a total of nearly 500 minutes taken over 3 nights) that went in to make up this image the track of an asteroid was seen lying above the bright star Alcyone (having a triplet of stars to its right).   The asteroid track was ~23 pixels in length so that, with a image scale of 3 arc seconds per pixel, the track spanned ~69 arc seconds.   The wonderful planetarium program 'Sky Safari Plus' showed this to be asteroid 769, Tatjana - though the position was not too accurate.   The Lowell Observatory asteroid finder chart software confirmed this and, from the precise positions of the asteroid at the start and end of the imaging session, determined that the track length should be ~70 arc seconds in length - agreeing very well with that observed.   The plots also showed that the asteroids motion was retrograde - that is westwards rather that eastwards.

769, Tatjana, lies at 3 AU from the Sun.   As it was imaged due south at midnight, its distance from the Earth was ~2 AU.  If the asteroid were stationary then, due to the Earth's motion of ~30km/sec around the Sun, it would appear to move in retrograde motion by ~170 arc seconds. However, if the Earth were stationary, the asteroid's speed of ~17km/sec would make it appear to move westwards in prograde motion by ~98 arc seconds so that the observed motion would appear to be ~72 arc seconds retrograde - again in nice agreement.

Highlights of the Month



January 2nd after sunset: Venus, Mars and the Moon

Venus, Mars and the Moon
Venus, Mars and the Moon
Image: Stellarium/IM

After sunset on the second of January there is a very nice grouping of Venus and Mars on either side of a very thin crescent Moon.   Do try to observe the 'old Moon' in the 'new Moon's' arms.   This is called 'Earthshine'.


January 19th - 1 hour before dawn: Jupiter between a third quarter Moon and Spica in Virgo.

Jupiter
Jupiter between the Moon and Spica in Virgo.
Image: Stellarium/IM

Before dawn on the 19th of January, if clear, one will be able to observe Jupiter lying between the Third Quarter Moon and Spica, Alpha Virginis..


January 24th and 25th, just before sunrise: Saturn, Mercury and a thin waning crescent Moon.

Saturn
Mercury, Saturn and a thin waning crescent Moon.
Image: Stellarium/IM

If it is clear on the mornings of the 24th and 25th and given a very low eastern horizon, Saturn and Mercury will be seen along with a very thin waning crescent Moon.   Binoculars may well be needed to spot Mercury, but please do not use them after the Sun has risen.


January 31st after sunset: A crescent Moon below Mars and Venus.

Venus and Mars
Venus and Mars above a waxing crescent Moon.
Image: Stellarium/IM

After sunset on the last day of January, one will, if clear, be able to spot a nice triangle made up of the planets Venus and Mars above a waxing thin crescent Moon.


January 7th: Two Great Lunar Craters

20thJuly
Tycho and Copernicus: Ian Morison

Two great Lunar Craters: Tycho and Copernicus
This is a great night to observe two of the greatest craters on the Moon, Tycho and Copernicus, as the terminator is nearby.   Tycho is towards the bottom of Moon in a densely cratered area called the Southern Lunar Highlands.   It is a relatively young crater which is about 108 million years old.  It is interesting in that it is thought to have been formed by the impact of one of the remnents of an asteroid that gave rise to the asteroid Baptistina.   Another asteroid originating from the same breakup may well have caused the Chicxulub crater 65 million years ago.   It has a diameter of 85 km and is nearly 5 km deep.   At full Moon - seen in the image below - the rays of material that were ejected when it was formed can be see arcing across the surface.   Copernicus is about 800 million years old and lies in the eastern Oceanus Procellarum beyond the end of the Apennine Mountains.   It is 93 km wide and nearly 4 km deep and is a clasic "terraced" crater.   Both can be seen with binoculars.

Tycho's Rays
Full Moon showing Tycho's rays: Ian Morison

A Messier Object imaged with the Faulkes Telescope: Messier 1 - The Crab Nebula

Messier 1
The Crab Nebula, M1
Image:Nik Szymanik
Faulkes Telescope North.

The Crab Nebula, M16, imaged by Nik Szymanek.
This image was taken using the Faulkes Telescope North by Nik Szymanek - one of the UK's leading astro-photograpers.   The Crab nebula - the first entry in Charles Messier's catalogue - is the remnant of a supernovae that was seen to explode in the year 1054.   It is visible as the lower right of the pair of stars at the centre of the nebula and is a "neutron star" just 30km across but weighing more than our Sun!   Under the intense pressure of gravity, the protons and electrons fused to form neutrons and the compact object became stable as gravity was opposed by "neutron degeneracy pressure" - a quantum mechanical force.   It is now spinning just under 30 times a second and emitting two opposed beams of light and radio waves which pass across our location in space.   We thus detect very regular pulses and so objects like this are called pulsars.   At 8.4 magnitudes it is easily seen in a small telescopes under dark transparent skies appearing as a smudge of light which is a little underwhelming to see!

Learn more about the Faulkes Telescopes and how schools can use them: Faulkes Telescope"

Observe the International Space Station

The International Space Station
The International Space Station and Jules Verne passing behind the Lovell Telescope on April 1st 2008.
Image by Andrew Greenwood

Use the link below to find when the space station will be visible in the next few days. In general, the space station can be seen either in the hour or so before dawn or the hour or so after sunset - this is because it is dark and yet the Sun is not too far below the horizon so that it can light up the space station. As the orbit only just gets up the the latitude of the UK it will usually be seen to the south, and is only visible for a minute or so at each sighting. Note that as it is in low-earth orbit the sighting details vary quite considerably across the UK. The NASA website linked to below gives details for several cities in the UK. (Across the world too for foreign visitors to this web page.)

Note: I observed the ISS three times recently and was amazed as to how bright it has become.

Find details of sighting possibilities from your location from: Location Index

See where the space station is now: Current Position


The Moon

3rd Quarter Moon
The Moon at 3rd Quarter. Image, by Ian Morison, taken with a 150mm Maksutov-Newtonian and Canon G7.
Just below the crator Plato seen near the top of the image is the mountain "Mons Piton".   It casts a long shadow across the maria from which one can calculate its height - about 6800ft or 2250m.
`
new moon first quarter full moon last quarter
January 28th January 5th January 12th January 19th

Some Lunar Images by Ian Morison, Jodrell Bank Observatory: Lunar Images

A World Record Lunar Image

World record Lunar Image
The 9 day old Moon.

To mark International Year of Astronomy, a team of British astronomers have made the largest lunar image in history and gained a place in the Guinness Book of Records! The whole image comprises 87.4 megapixels with a Moon diameter of 9550 pixels. This allows details as small as 1km across to be discerned! The superb quality of the image is shown by the detail below of Plato and the Alpine Valley. Craterlets are seen on the floor of Plato and the rille along the centre of the Alpine valley is clearly visible. The image quality is staggering! The team of Damian Peach, Pete lawrence, Dave Tyler, Bruce Kingsley, Nick Smith, Nick Howes, Trevor Little, David Mason, Mark and Lee Irvine with technical support from Ninian Boyle captured the video sequences from which 288 individual mozaic panes were produced. These were then stitched together to form the lunar image.

Plato and the Alpine valley
Plato and the Alpine Valley.

Please follow the link to the Lunar World Record website and it would be really great if you could donate to Sir Patrick Moore's chosen charity to either download a full resolution image or purchase a print.



The Planets

 A montage of the Solar System
A montage of the Solar System. JPL / Nasa

Jupiter

Jupiter
A Cassini image of Jupiter . Nasa

Jupiter shining at magnitude -1.9 (increasing to magnitude -2.1 during the month), rises at around midnight at the beginning of the month lying low in Virgo not far above Spica.   Towards month's end it will lie just over 3 degrees away.   It will be due south and so highest in the sky at an elevation of 35 degrees in the pre-dawn sky.   As the Earth moves towards Jupiter, the size of Jupiter's disk increases from 35.5 to 38.9 arc seconds so one should be easily able to see the equatorial bands in the atmosphere, sometimes the Great Red Spot and up to four of the Gallilean moons as they weave their way around it.   [Note: As all the major planets drop to the southern part of the ecliptic their elevation, even due south, will not be that high and dispersion in the atmosphere will blur our view.   It is now possible to buy the ZWO Atmospheric Dispersion Corrector for ~120 from 365 Astronomy which uses two contra-rotating prisms to correct for this and so could be a very worthwhile accessory for both viewing and imaging in the coming years.]


See highlight above.


Saturn

Saturn
The planet Saturn. Cassini - Nasa

Saturn, having passed behind the Sun on December 10th, is now a morning object seen low in the southeast at dawn rising about one and a half hours before the Sun on New Year's Day and by three hours by month's end.   It lies in the southern part of Ophiuchus some 16 degrees to the left of Antares in Scorpius.   With a magnitude of +0.5, its angular diameter increases from 15.2 to 15.5 arc seconds during the month with its ring system spanning some 35 arc seconds.   Its beautiful ring system has now opened out to ~26.7 degrees - virtually as open as they can be - but we will have to wait a few months to see them at their best.


See highlight above.


Mercury

Mercury.
Messenger image of Mercury Nasa

Mercury becomes visible in the pre-dawn sky by the second week of the month down to the left of Saturn.   By the 6th it will have reached magnitude +0.9.   Binoculars will be probably needed to spot it but please do not use them until after the Sun has risen.   Over the next week or so it begins to fall back towards the horizon, but its magnitude increases to a maximum of -0.2 on the 21st and remains at this brightness during the remainder of the month - but it will become increasingly difficult to spot in the Sun's glare.



See highlight above.





Mars

Mars showing Syrtis major.
A Hubble Space Telescope image of Mars.
Jim Bell et al. AURA / STScI / Nasa

Mars, moving eastwards relative to the stars, starts the month in Aquarius but moves into the southern part of Pisces on the 19 of January.   Its brightness reduces slightly during the month from magnitude +0.9 to +1.1 as the angular size of its disk reduces from 5.7 to 5.1 arc seconds.   It will be easily found up to the left of Venus which is rapidly approaching it and will be just 5.5 degrees away by months end.   With its small angular size, one would not expect to see any details on its salmon-pink surface.



See highlights above.





Venus

Venus
Venus showing some cloud structure

Venus dominates the western sky this month, reaching its greatest elongation from the Sun on the 12th - some 47 degrees to its east.  . It begins the month in Aquarius but moves into Pisces on the 23rd.   Venus sets around three and a half hours after the Sun.   As Venus moves northwards along the ecliptic its elevation at sunset increases from ~27 to 36 degrees.   Its angular size increases from 21.7 to 30.4 arc seconds during the month but, as it does so, the percentage of the disk which is illuminated reduces from 57 to 40% and the brightness hardly changes, increasing from -4.4 to (near maximum) -4.7 during the month.



See highlights above.



Radar Image of Venus
Radar image showing surface features



Find more planetary images and details about the Solar System: The Solar System



The Stars

The Mid to Late Evening January Sky

JanuarySky
The January Sky in the south - mid to late evening.

This map shows the constellations seen in the south around midnight.   The brilliant constellation of Orion is seen in the south.   Moving up and to the right - following the line of the three stars of Orion's belt - brings one to Taurus; the head of the bull being outlined by the V-shaped cluster called the Hyades with its eye delineated by the orange red star Aldebaran.   Further up to the right lies the Pleaides Cluster.   Towards the zenith from Taurus lies the constellation Auriga, whose brightest star Capella will be nearly overhead.   To the upper left of Orion lie the heavenly twins, or Gemini , their heads indicated by the two bright stars Castor and Pollux.   Down to the lower left of Orion lies the brightest star in the northern sky, Sirius, in the consteallation Canis Major.   Finally, up and to the left of Sirius is Procyon in Canis Minor.   There is also information about the constellation Ursa Major, seen in the north,in the constellation details below.

The constellation Taurus

Taurus
Taurus

Taurus is one of the most beautiful constellations and you can almost imagine the Bull charging down to the left towards Orion.   His face is delineated by the "V" shaped cluster of stars called the Hyades, his eye is the red giant star Aldebaran and the tips of his horns are shown by the stars beta and zeta Tauri.   Although alpha Tauri, Aldebaran, appears to lie amongst the stars of the Hyades cluster it is, in fact, less than half their distance lying 68 light years away from us.   It is around 40 times the diameter of our Sun and 100 times as bright.

The Pleiades
AAO Image of the Pleiades, M45, by David Malin

To the upper right of Taurus lies the open cluster, M45, the Pleiades.   Often called the Seven Sisters, it is one of the brightest and closest open clusters.   The Pleiades cluster lies at a distance of 400 light years and contains over 3000 stars.   The cluster, which is about 13 light years across, is moving towards the star Betelgeuse in Orion.   Surrounding the brightest stars are seen blue reflection nebulae caused by reflected light from many small carbon grains.   These relfection nebulae look blue as the dust grains scatter blue light more efficiently than red.   The grains form part of a molecular cloud through which the cluster is currently passing.   (Or, to be more precise, did 400 years ago!)

The Crab Nebula
VLT image of the Crab Nebula

Close to the tip of the left hand horn lies the Crab Nebula, also called M1 as it is the first entry of Charles Messier's catalogue of nebulous objects.   Lying 6500 light years from the Sun, it is the remains of a giant star that was seen to explode as a supernova in the year 1056.   It may just be glimpsed with binoculars on a very clear dark night and a telescope will show it as a misty blur of light.

The Crab Nebula
Lord Rosse's drawing of M1

Its name "The Crab Nebula" was given to it by the Third Earl of Rosse who observed it with the 72 inch reflector at Birr Castle in County Offaly in central Ireland.   As shown in the drawing above, it appeared to him rather lile a spider crab.   The 72 inch was the world's largest telelescope for many years.   At the heart of the Crab Nebula is a neutron star, the result of the collapse of the original star's core.   Although only around 20 km in diameter it weighs more than our Sun and is spinning 30 times a second.   Its rotating magnetic field generate beams of light and radio waves which sweep across the sky.   As a result, a radio telescope will pick up very regular pulses of radiation and the object is thus also known a Pulsar.   Its pulses are monitored each day at Jodrell Bank with a 13m radio telescope.





The constellation Orion

Orion
Orion

Orion, perhaps the most beautiful of constellations, will be seen in the south at around 11 - 12 pm during January.   Orion is the hunter holding up a club and shield against the charge of Taurus, the Bull up and to his right.   Alpha Orionis, or Betelgeuse, is a read supergiant star varying in size between three and four hundred times that of our Sun.   The result is that its brightness varies somewhat.   Beta Orionis, or Rigel, is a blue supergiant which, at around 1000 light years distance is about twice as far away as Betelgeuse.   It has a 7th magnitude companion.   The three stars of Orion's belt lie at a distance of around 1500 light years.   Just below the lower left hand star lies a strip of nebulosity against which can be seen a pillar of dust in the shape of the chess-board knight.   It is thus called the Horsehead Nebula.   It shows up very well photographically but is exceedingly difficult to see visually - even with relativly large telescope.

The Orion Nebula
The Horsehead Nebula: Anglo Australian Observatory

Beneath the central star of the belt lies Orion's sword containing one of the most beautiful sights in the heavens - The Orion Nebula.   It is a region of star formation and the reddish colour seen in photographs comes from Hydrogen excited by ultraviolet emitted from the very hot young stars that make up the Trapesium which is at its heart.   The nebula, cradling the trapesium stars, is a beautiful sight in binoculars or, better still, a telescope.   To the eye it appears greenish, not red, as the eye is much more sensitive to the green light emitted by ionized oxygen than the reddish glow from the hydrogen atoms.

The Orion Nebula
The Orion Nebula: David Malin


The constellation Ursa Major

Ursa Major
Ursa Major

The stars of the Plough, shown linked by the thicker lines in the chart above, form one of the most recognised star patterns in the sky.  Also called the Big Dipper, after the soup ladles used by farmer's wives in America to serve soup to the farm workers at lunchtime, it forms part of the Great Bear constellation - not quite so easy to make out!   The stars Merak and Dubhe form the pointers which will lead you to the Pole Star, and hence find North.   The stars Alcor and Mizar form a naked eye double which repays observation in a small telescope as Mizar is then shown to be an easily resolved double star.   A fainter reddish star forms a triangle with Alcor and Mizar.

Ursa Major contains many interesting "deep sky" objects.   The brightest, listed in Messier's Catalogue, are shown on the chart, but there are many fainter galaxies in the region too.   In the upper right of the constellation are a pair of interacting galaxies M81 and M82 shown in the image below.   M82 is undergoing a major burst of star formation and hence called a "starburst galaxy".   They can be seen together using a low power eyepiece on a small telescope.

M81 and M82
M81 and M82

Another, and very beautiful, galaxy is M101 which looks rather like a pinwheel firework, hence its other name the Pinwheel Galaxy.   It was discovered in1781 and was a late entry to Messier's calalogue of nebulous objects.   It is a type Sc spiral galaxy seen face on which is at a distance of about 24 million light years. Type Sc galaxies have a relativly small nucleus and open spiral arms.   With an overall diameter of 170,000 light it is one of the largest spirals known (the Milky Way has a diameter of ~ 130,000 light years).

M101
M101 - The Ursa Major Pinwheel Galaxy

Though just outside the constellation boundary, M51 lies close to Alkaid, the leftmost star of the Plough.   Also called the Whirlpool Galaxy it is being deformed by the passage of the smaller galaxy on the left.   This is now gravitationally captured by M51 and the two will eventually merge.   M51 lies at a distance of about 37 million light years and was the first galaxy in which spiral arms were seen.   It was discovered by Charles Messier in 1773 and the spiral structure was observed by Lord Rosse in 1845 using the 72" reflector at Birr Castle in Ireland - for many years the largest telescope in the world.

M51
M51 - The Whirlpool Galaxy

Lying close to Merak is the planetary nebula M97 which is usually called the Owl Nebula due to its resemblance to an owl's face with two large eyes.   It was first called this by Lord Rosse who drew it in 1848 - as shown in the image below right.   Planetary nebulae ar the remnants of stars similar in size to our Sun.   When all possible nuclear fusion processes are complete, the central core collpses down into a "white dwarf" star and the the outer parts of the star are blown off to form the surrounding nebula.



Owl Nebula                                        Owl Nebula
          M97 - The Owl Planetary Nebula             Lord Rosse's 1848 drawing of the Owl Nebula