WHAT'S UP THIS MONTH - NOVEMBER 2020

(Link to What's Up December 2020)

(Link to What's Up October 2020)

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THESE PAGES ARE INTENDED TO HELP YOU FIND YOUR WAY AROUND THE SKY

The chart above shows the whole night sky as it appears on 15th November at 21:00 (9 o'clock) in the Greenwich Mean Time (GMT). As the Earth orbits the Sun and we look out into space each night the stars will appear to have moved across the sky by a small amount. Every month Earth moves one twelfth of its circuit around the Sun, this amounts to 30 degrees each month. There are about 30 days in each month so each night the stars appear to move about 1 degree. The sky will therefore appear the same as shown on the chart above at 10 o'clock GMT at the beginning of the month and at 8 o'clock GMT at the end of the month. The stars also appear to move 15º (360º divided by 24) each hour from east to west, due to the Earth rotating once every 24 hours.

The centre of the chart will be the position in the sky directly overhead, called the Zenith. First we need to find some familiar objects so we can get our bearings. The Pole Star Polaris can be easily found by first finding the familiar shape of the Great Bear ‘Ursa Major' that is also sometimes called the Plough or even the Big Dipper by the Americans. Ursa Major is visible throughout the year from Britain and is always quite easy to find. This month it is in the North. Look for the distinctive saucepan shape, four stars forming the bowl and three stars forming the handle. Follow an imaginary line, up from the two stars in the bowl furthest from the handle. These will point the way to Polaris which will be to the north of overhead at about 50º above the northern horizon. Polaris is the only moderately bright star in a fairly empty patch of sky. When you have found Polaris turn completely around and you will be facing south. To use this chart, position yourself looking south and hold the chart above your eyes.

Planets observable in the evening sky: Jupiter, Saturn, Neptune, Mars and Uranus.

EXPLORING THE NIGHT SKY THIS MONTH

The Southern Night Sky 15th November 2020 at 19:00 GMT

The chart above shows the night sky looking south at about 19:00 GMT on 15th November.

The tour of the night sky this month starts early because the beautiful planets Jupiter and Saturn are moving ever closer towards the western horizon. They will be setting over the horizon at 20:30 in the beginning of November and at 19:30 at the end of the month. Fortunately the sky is getting dark earlier so there is still time to see the two Gas Giants appearing very close together in their planetary conjunction. They will be at their closest on 21st December when the pair will be visible together in the field of view of telescopes using a low power eyepiece.

West is to the right and east to the left. The point in the sky directly overhead is known as the Zenith or Nadir and is shown at the centre of the chart. The curved brown line across the sky at the bottom is the Ecliptic or Zodiac. This is the imaginary line along which the Sun, Moon and planets appear to move across the sky. The brightest stars often appear to form a group or recognisable pattern; we call these ‘Constellations'.

Constellations through which the ecliptic passes this month are Sagittarius (the Archer), Capricornus (the Goat), Aquarius (the Water Carrier), Pisces (the Fishes), Aries (the Ram), Taurus (the Bull), Gemini (the Twins) and Cancer (the Crab, just off the chart to the east).

Just disappearing over the south western horizon is the constellation of Sagittarius (the Archer). It is really a southern constellation but we can see the upper part creep along the horizon during the summer. The central bulge of our galaxy is located in Sagittarius so the richest star fields can be found in the constellation along with many of the beautiful and interesting deep sky objects that we seek out ( labelled in yellow print). The stunning binocular cluster M45 the Pleiades (Seven Sisters) are looking beautiful in Taurus towards the east of the Ecliptic.

The summer constellations are still prominent in the early night sky. The Summer Triangle with its three corners marked by the bright stars: Deneb in the constellation of Cygnus, Vega in Lyra, and Altair in Aquila. The Summer Triangle is very prominent and can be used as the starting point to find our way around the night sky. The Milky Way (our Galaxy) flows through the Summer Triangle passing through Cygnus, down to the horizon in Sagittarius. The Milky Way flows north from the Summer Triangle through the rather indistinct constellation of Lacerta (the Lizard), past the pentagon shape of Cepheus and on through the ‘W' shape of Cassiopeia (a Queen), Perseus and Auriga (The Charioteer).

All the Superior Planets (those orbiting the Sun outside Earth's orbit) are visible in the south. Jupiter and Saturn are most prominent in the south west in the early evening. Jupiter is very bright with Saturn very close by and getting closer still until they are very close together on 21st December (their closest CONJUNCTION). The Gas Giant Planets are followed across the sky by Neptune the most distant planet then the distinctly orange and bright Mars and completing the parade of planets is Uranus. The outermost planets Uranus and Neptune do really need a good large pair of binoculars to find and a telescope to see as small blue discs.

Mars was at its closest to Earth on 13th October when it was at Opposition (in the south at midnight GMT) and at its brightest this year. It is now moving away from us and will start looking smaller.

Planets observable: Jupiter, Saturn (early evening, Neptune, Mars, Uranus (in the evening), Venus and Mercury (in the early morning in the east before sunrise).

There will be a Meteor shower called the Leonid Meteor Shower with a peak of activity in the early hours of the 18th November.

 

CONSTELLATIONS OF THE MONTH – PEGASUS AND ANDROMEDA

The constellations of Pegasus and Andromeda to the east (left) of the Summer Triangle

The constellations of Pegasus and Andromeda share and are joined at the star Alpheratz. Alpheratz is actually designated as belonging to Andromeda but looks to be more a part of Pegasus as it is required to complete the familiar ‘Great Square of Pegasus'. The Great Square is larger than may be expected when first sesrching for it which sometimes makes it a little difficult to initially identify. However once it has been identified it is easier to find again in a clear dark sky.

The constellation of Pegasus

Pegasus is named after the mythical winged horse and with Andromeda included to provide the wings and a lot of imagination the stars could be said to resemble the flying horse. The square generally is used to represent the body of the horse and the three lines to the west (right) of the stars Scheat and Markab do look a little like the horse's legs.

The square can be used to judge the seeing condition of the night sky. Under perfect conditions about ten stars can be seen, using our ‘naked eyes', inside the square so this would indicate a very good night for observing. If three to five stars can be seen then conditions will still be good. If fewer than five or none can be seen then stick to looking at the Moon or planets.

There is a very nice Globular cluster in Pegasus it is known as Messier 15 (M15). It is a lovely sight to see in a medium to large telescope.

Messier 15 (M15) the Globular Cluster in Pegasus

To find M15 start at the star Markab, located at the bottom right of the Great Square (see the preceding charts). Follow the fainter line of stars to the west (right) to the star Baham then North West (up and right) to the star Enif, see the charts above and the previous column. Continue the imaginary line on for about the same distance to find the fuzzy patch that will be the Globular Cluster M15. M15 can just be seen using binoculars but really needs a telescope.

Globular Clusters are generally spherical clusters of between 10,000 and 1 million stars. They are thought to be the central core of smaller galaxies that have had their outer stars torn away in close encounters with our Giant Spiral Galaxy that we call the Milky Way. M15 is the second brightest Globular Cluster that can be seen from the UK. M13 in the constellation of Hercules is the largest and brightest. It can be seen using binoculars but looks beautiful when using a telescope.

There is thought to be about one hundred Globular Clusters orbiting the centre of our Galaxy (The Milky Way). They do not move round in the flat disc structure of the Galaxy, like most of the other material. They appear to follow random orbits in a sort of halo surrounding the Galaxy. Amazingly Globular Clusters can and do even pass through the spiral arms in the flat disc structure of the Galaxy. As the stars in the globular cluster and the galaxy are so far apart compared to their size they very rarely if ever collide. The stars appear to just past through the stars of the Galaxy almost ghost like.

 

SPECIAL CONSTELLATION OF THE MONTH – ANDROMEDA

A chart of the Constellation of Andromeda

The constellation of Andromeda is host to the only ‘naked eye' Galaxy that we call Messier 31 (M31). It is the most distant object that can be seen with our naked eyes (2.4 million light years away). It is quite easy to find using binoculars and is getting well placed at this time of year. The easiest way to find M31 is to first locate the Great Square of Pegasus. Once the square is found the pointer to Andromeda is the top left star of the square named Alpheratz. Strangely Alpheratz is officially not part of Pegasus but is designated as Alpha (a) Andromedae. From Alpheratz follow the fairly obvious line of stars to the left (east). Locate the second star in the line which is shown as Mirach on the chart above. From Mirach follow a slightly fainter short line of stars to the north (above) Mirach and up to the second star. Just to the right of this star is the faint fuzzy patch of light, that is M31 the Great Andromeda Galaxy. See the chart above.

Messier 31 (M31) as seen in the sky (with lines and names added)

The Image above shows M31 imaged through a small telescope. The image is much clearer than can be hoped to be seen with the naked eye. However a pair of binoculars will enable the galaxy to be seen looking similar but not so bright and less stars. A small telescope will show a cigar shaped hazy patch with a brighter spot in the centre. Larger telescopes will show it more clearly but photographic imaging is required to reveal its true nature. See the image below.

Messier 31 (M31) the Great Spiral Galaxy in Andromeda

At the end of the lower line of stars that mark out the constellation of Andromeda is the star Almach or (Almaach). It is a beautiful example of a pair of stars that are not physically related. They are thought to be at different distances but appear to be in the same ‘line of sight' as seen from Earth. The apparently brighter golden coloured star is thought to be located much nearer to us than the apparently fainter blue star. The blue star is in fact a Blue Giant, a very hot and powerful star that is many thousands of times brighter than the golden star but much further away. A telescope is required to separate this beautiful double.

Almach the ‘line of sight' double star in Andromeda

THE LEONID METEOR SHOWER

The Radiant of the Leonid Meteor Shower at its peak at 05:00 on 18th November

Meteor showers are notoriously unpredictable. The exact time of any spectacular increase in numbers or if the meteors will be bright is as difficult to predict as is the clear weather needed to see them. However every year on the evening of the 17th and morning of 18th November there is usually a spectacular display from the peak of activity during the Leonid Meteor Shower.

Fortunately this year the Moon will not be a in the night sky so even some of the fainter meteors may be seen. The meteors of a shower appear to radiate from a point in the sky that is called the ‘Radiant'. The meteors of this particular shower appear to originate from a ‘Radiant' point in the constellation of Leo. See the chart above. This radiant effect is similar to what we see when driving a car into a snow storm or heavy rain. The snow or rain appears to radiate from a point directly ahead of the car. After midnight, the night side of Earth is onthe 'front' side of the planet as it speeds along it orbit of the Sun. Therefore as we plough into the meteoroids (specs of dust) we see them appearing from a radiant point directly ahead of Earth.

The radiant point of the Leonid Meteor Shower is shown close to the star Algieba. The paths of the meteors are shown by the straight lines emanating from the direction of the radiant point. The meteors are small specks of dust debris from the Comet Temple Tuttle.

During the evening of 17th November the constellation of Leo will be below the eastern horizon so any Leonid meteors will appear to originate from over the eastern horizon. This means all the meteors will be moving up from the eastern horizon and in a ‘fan' shape across the sky. Leonid meteors tend to be fast and relatively bright so look anywhere from the eastern horizon to overhead.

If the trail of any meteor that is seen can be tracked back and found to have originated from this radiant point it will be a Leonid Meteor. A few meteors might appear to originate from other directions so these are the meteors that might be seen randomly and not part of any named shower. These are known as Sporadic Meteors.

Make sure you are dressed warmly with a hat and gloves and sitting comfortably. A garden lounger chair will allow the observer to lay back and have their head supported to avoid getting a neck ache from looking up.

On any clear night if you sit back and look up into the night sky for a while you will more than likely see a streak of light speed across the sky - this will be a METEOR or shooting star. It is not a star at all it is just a small speck of dust known as a METEOROID entering the Earth's atmosphere at very high speed.

This is like when the space shuttle or other space craft become very hot as they re-enter the atmosphere at about 30 thousand km/h . However these dust particles get even hotter at their re-entry speed of up to 270 thousand km/h. At this speed the dust is vaporised by the heat created by the friction with the upper atmosphere at an altitude of about 80km. T he surrounding air is also heated until it glows in a similar way to a fluorescent light.

There are two types of Meteor, the first is thought to originate from the large lumps of rock and iron left over when the planets formed , known as ASTEROIDS. Most asteroids orbit the Sun in a belt between Mars and Jupiter. The huge gravitational forces exerted by Jupiter may have pulled the rocks apart before they could accumulate into a nother planet.

Very rarely two asteroids may randomly collide but when they do, chips of rock and Iron are thrown off and occasionally may be sent spiralling in towards the Sun and Earth. These can be a few millimetres across or up to tens or even hundreds of metres across. They are quite rare and are seen as individual ‘fireballs' . Large ones can sometimes impact the ground as METEORITES and may even cause craters but these are very rare .

The second type of meteor originates from a comet and is much more common. Comets are large lumps of ice, typically between five and thirty kilometres across. They orbit the Sun in an area beyond the orbits of the outer planets called the Kuiper Belt. There are thought to be millions of these objects just sitting there quietly orbiting around the Sun at enormous distances.

Occasionally two of these lumps of ice may have a close encounter and their gravity can slightly perturb their orbits. This may move the objects enough that one might change its orbit so that will spiral in for a close encounter with the Sun. As this object, that can be thought of as a very large and dirty snowball, approaches the Sun the ice begins to melt. In the vacuum of space the frozen water will turn directly into water vapour and not pass through the liquid phase. This is called subliming.

As the ice melts the water vapour forms a cloud (called a Coma) around the solid object that is called the Nucleus. The Solar Wind (radiation from the Sun) drives the water vapour and other gases away from the coma and the familiar tail of the Comet is formed. Dust particles are released from the melting ice and slowly leave a trail along the path of the Comet as it loops around the Sun.

Comets mainly move around the Sun in very elliptical orbits that may take them out beyond the outer planets into long orbits. Some comets may have orbits taking a few decades to complete but others may take thousands of years. Every time they visit the inner Solar System they leave a dust trail along their orbit. Eventually this trail may become a ring of dust around the Sun.

This ring is tilted compared to the orbit of the planets around the Sun. Some of the dust trails spread across the orbit of Earth so once, or sometimes twice, a year Earth will pass through the dust trail. When Earth, travelling at ~108,000km/h crashes into these dust particles (that may also be travelling at a similar speed towards Earth) the combined speed of up to 270,000km/h produces a huge amount of energy. This energy is converted into heat by the friction of the dust particle with the upper atmosphere and the streak of light we call a Meteor is produced. This is the kind of meteor seen in the Leonid Shower.

The orbit of Comet Temple Tuttle

 

THE INNER SOLAR SYSTEM - NOVEMBER 2020

The morning sky at 07:00 (in the morning) showing the positions Mercury and Venus

MERCURY will be in it best position for observing in the early morning sky in the east this year on 10th November. See the chart above (the sky has been darkened to allow the planets to be seen).

VENUS reached its greatest western elongation (at its furthest apparent distance from the Sun) on 14th August. It is still rising in the in the east before the Sun rises. It now appears ‘gibbous' (wider than half Moon shaped see below).

It is moving back towards the Sun and will appear smaller but ‘fuller' as it moves into Superior Conjunction (behind the Sun) on 25th March 2021. After passing through Superior Conjunction Venus will reappear in the evening sky in the west as the Sun is setting.

Venus appearing ‘Gibbous' during November

After conjunction Venus will first appear close to the Sun and will be round when viewed using a telescope. As it will be located on the other side of the Sun it will fully illuminated but will become larger and crescent shaped as it moves out from the Sun and towards us.

Venus can be observed during the day in the sunlit sky but this must only be done with great care. A GOTO telescope would be best but setting circles can be used. The dust cap must only be removed when it is confirmed that the Sun is not in view through the telescope.

OBSERVING VENUS

A comparison of Venus and Earth the non-identical twins

Venus has a very thick and clouded atmosphere that covers the whole surface. Consequently there are no surface features to see. All that is visible on Venus is the top of the thick white clouds. Some faint features can be seen in the clouds but special filters are required to see them.

The main interest for amateur astronomers when observing Venus is to follow the progress of the phases. The two inner planets Mercury and Venus (known as Inferior Planets) are the only planets to show phases. Phases occur when these planets (and our Moon) are partially illuminated by the Sun. The phases change as the planets move around the Sun on their orbits.

Venus (upper right) in the early morning of the 15th October with the 'Old Moon' (enlarged).

Venus is currently on view in the east before sunrise in the early morning see the photo above. The chart below shows the location of Venus and its orbital path. Venus was in Inferior Conjunction (between Earth and the Sun) on 3rd June 2020 when it was not visible. As it moved out from Inferior Conjunction and away from the Sun, it followed the orbital path that appears to loop out from the Sun and then back again. The brighter part of the orbit shows the path out from conjunction.

Venus in the early morning and its orbital path

The furthest point from the Sun (Greatest Western Elongation) was reached on 13th August then Venus started to move back towards the Sun. It will be in Superior Conjunction (pass behind the Sun) on 26th March 2021. As Venus moves out from Superior Conjunction it will appear as a small, full disc in the west in the evening. It will appear small in diameter because it will be at its most distant point from Earth on the opposite of the Sun and fully illuminated by the Sun.

Venus in the evening sky at sunset and its orbital path

When Venus emerges from its Superior Conjunction behind the Sun it will appear to the east of the Sun in the Evening sky at sunset. See the chart below. It will be small but full, close to the western horizon and in the bright sky after sunset. It is sometimes called the Evening Star. As Venus appears to move further east and away from the Sun it will also be moving towards Earth. It will begin to appear larger in diameter but less will be illuminated by the Sun. See the images below.

.The phases of Venus from Gibbous (left) to Thin Crescent (right)

As Venus moves out from Superior Conjunction it appears as a full disc because it is on the opposite side of the Sun to us. From our point of view we see the whole surface of Venus illuminated. Venus then moves on its orbit around the Sun and appears to us to move away from the Sun to the east (left). As it moves further away from the Sun its orbit also brings it towards us so some of the illuminated surface begins to disappear from our view. See the images above.

After about 70 (Earth) days Venus will have moved a quarter of its way around the Sun and will be at its apparent furthest point from the Sun as we see it so we call this Greatest Easterly Elongation. At this point Venus will be the same distance from us as the Sun so we will see the half of Venus facing the Sun illuminated and appearing ‘Half Moon' shaped. See the chart above. Up to this point more than half of Venus would have been illuminated and the apparent shape would have been more than half, a shape we call ‘Gibbous'. Actually the Greatest Easterly Elongation occurs after the point when Venus is half way around its orbit and occurs when Venus is at 90º from the Sun as we see it from Earth as shown on the diagram below (dotted lines). .

The Orbit, Phases, Conjunctions and Elongations of Venus

Venus appears bright in the east as the Sun is rising and is often called the ‘Morning Star'. It will also appear to be moving away from us as it moves further around its orbit and behind the Sun. Therefore it will appear to become smaller but fully illuminated. It will eventually disappear from view in the brighter glare close to the Sun.

Venus imaged as a wide crescent by the author

We have already seen that Venus has an orbital period (year) equivalent to 226.5 Earth days but its axial rotation (day) is equivalent to 243 Earth days. This means a day on Venus is, very oddly, longer than its year. However this makes no difference on the surface because the Sun is never visible due to the very thick Carbon Dioxide (CO 2) clouds .

The period taken for Earth to catch up with another planet is called the Synodic Period and the time taken for a planet to complete one orbit around the Sun is called its Sidereal Period. The table below shows the Synodic and Sidereal Periods for Earth and the other planets..

Planet

Synodic Period (days)

Sidereal Period

Mercury

116 (~3x y)

88 days

Venus

584 (~1.5x y)

225 days

Earth

-

1.0 year

Mars

780 (2.137y)

1.9 years

Jupiter

399 (y + ~34d)

11.9 years

Saturn

378 (y + ~13d)

29.5 years

Uranus

370 (y + ~5d)

84.0 years

Neptune

368 (y + ~3d)

164.8 years

Table showing the Synodic Periods of the planets

From a point where Earth and Venus are in the same point on their orbits as on the diagram opposite, at Inferior conjunction, Earth will take 365.25 days to return to the same spot. As the orbit of Venus is inside the orbit of Earth it completes its orbit of the Sun in just 225 Earth days. When Venus catches up with Earth it will have completed 2.6 of its own orbits. Earth will have needed to move around its orbit for 584 days for Venus to catch up. This is called the Synodic Period of Venus.

The orbits of Venus and Earth

A telescope is needed to see Venus as a disc and the larger the telescope the bigger Venus will appear. Venus often appears low in sky and in the murky and turbulent air close to horizon. It is best to start with a low power eyepiece (25mm) when observing Venus then use a higher power (magnification) eyepiece (10mm) to have a closer look. If the image is too bright then a Moon filter can be used. Alternatively the Dust cap can be fitted to the telescope and the small ‘Moon' cap removed to reduce the glare.

If the image looks good then a Barlow Lens can be used to effectively double the magnification of the 10mm eyepiece. When Venus is low in the sky and we are looking through more of the atmosphere some colour distortion can be seen as red and blue fringes.

MARS rises in the east at about 18:00 and is still looking quite large at about 17 arc-seconds. Earth caught up and passed Mars on their orbits around the Sun. This was because Earth's orbit is inside the orbit of Mars and is consequently travelling faster. Earth overtook Mars on 13th October and this is called Opposition. At opposition Mars was in direct line with Earth and the Sun as shown below.

Mars at Opposition on 13th October 2020

At opposition Mars was at it its closest point to Earth on this orbit. It can be seen on the chart above that the orbit of Mars is quite eccentric. The closest and furthest points possible are marked on the orbit. This opposition brings the two planets quite close together so Mars will appear significantly larger than it would appear at the ‘furthest' conjunction point on its orbit. Mars was actually at its very closest on 6 th October at 62.07 million km.

Mars will still be in a good position for observing for another month or so but will be moving closer to the south western horizon. It will also be quickly reducing in size. After it has moved over the horizon we will not see it again for two years.

OBSERVING MARS

Hubble images with the main features on Mars labelled

The picture above shows the main features that may be identified on the surface of Mars labelled for identification. It must be pointed out that the view of mars as seen through the average amateur astronomer's telescope will not be as clear as those shown in pictures above. The very best view possible using ~200x magnification and a medium sized telescope (120mm) on a very still clear night is likely to be something like the image below.

A good image through the eyepiece of a small telescope

Before starting to observe Mars point the telescope towards a fairly distant object during the day, a chimney is a good target. Take note of the orientation of the image to see if it is upside down or back to front? This will help with identifying features on Mars. The images above are the right way up (north at the top). Conventionally astronomically images are shown upside down to conform to the way the planet or our Moon. However these days the images are often shown the right way up that is with North up.

The rotation period of Mars is almost 40 minutes longer than Earth's, at 24 hours, 39 minutes and 35 seconds. This means that features centrally located on Mars' disc appear 40 minutes later on each consecutive night. This rotation speed also means half of the surface of Mars can be seen over the course of one night's viewing. During December we have eighteen hours of darkness so plenty of time to watch Mars rotate through 12 hours of its 24.6 hour day. That is if the weather and the observer's persistence permit.

Imagine looking at Mars one night and seeing a dark feature at the centre of its disc (what's known as the Central Meridian of Mars). The following night at exactly the same time, that feature would appear slightly further west and take an extra 40 minutes to reach the central meridian once again. The night after that, viewing at the same time, the feature would take 80 minutes to reach the central meridian.

A telescope is needed to see Mars as a disc and the larger the telescope the more detail can be seen. The ‘seeing conditions' (the clarity and stability of our atmosphere) is a very important factor for having a good view. Use a low power eyepiece (25mm) to start observing Mars then use a higher power (magnification) eyepiece (10x) to have a good look. If the image looks good then a Barlow Lens can be used to effectively double the magnification of the 10mm eyepiece. As Mars gets larger, its surface detail should be easier to see (it will be at its very closest and largest on 6 th October).

Mars imaged by Steve Harris on 13th September 2020

The image above was taken using a modified (shop bought) webcam from the Orion range through a larger 300mm aperture telescope with a long focal length of 3000mm. Smaller telescopes can be used and can produce good images. The darker features shown on this image can be seen using a 100mm aperture telescope with a focal length of about 1000mm and fitted with a 2x Barlow Lens to give an effective focal length of 2000mm. Mars will appear smaller in a 100mm telescope and appear in the eyepiece and appear similar to the previous image to the image above.

The bright southern polar cap should be quite easy to see even using a smaller telescope. The planet surface has areas of light and dark, representing deserts and exposed rock. These are known as Albedo features, areas that appear bright or dark due to the amount of light they reflect. The larger and darker an albedo feature is the easier it is to see through a telescope.

Probably the easiest feature to recognise is Syrtis Major shown on the right Hubble image above. This large triangular feature points to the North Pole of Mars as can be seen in the Hubble image so North is up. So try to identify this feature if it is in view. Between the southern boundary of Syrtis Major and the southern polar cap lies the Hellas Basin. This 2,300km diameter basin is one of the largest impact craters in the Solar System. Hellas can sometimes appear bright due to clouds that can form in the basin.

The Hubble images above can be used to identify features seen through our telescope or on photographic images that we have produced. HST images can be downloaded for the view we are expecting during the planned observing period.

 

THE GAS GIANT PLANETS – NOVEMBER 2020

 

The chart above shows the positions of the Gas Giant Planets this month low in the west in the early night sky after sunset this month. Jupiter and Saturn are moving closer together in the Conjunction (close together in the sky). They will be at their closest on 21st December.

This is an interesting event , involving Jupiter and Saturn. It will develop and become even more interesting through the months from now until the end of this year. Jupiter and Saturn are located close together in the sky at the moment and this is what astronomers call a ‘Conjunction'. This is a term used when two (or more) objects appear to move close together in the sky. See the chart above.

Saturn and Jupiter as they appeared on 26th October imaged using a DSLR camera - Steve Harris

The two Gas Giant Planets have appeared close together in the sky all summer and will continue to move even closer together until the end of the year. The converging orbital paths of the planets are shown on the chart below.

Orbital paths of Jupiter and Saturn 21st December

The orbital paths of the planets are show as red for Jupiter and brown for Saturn. It can be seen on the chart above that the orbital paths a getting closer towards the end of the year as the planets move further west.

Unfortunately Jupiter and Saturn have been low in the southern sky this year and not in a good position for observing. They have been in the thick and turbulent air close to the southern horizon so it has been difficult to see the surface details. However the Planetary Conjunction next month should make up for the disappointing views of the planets. A clear view to the western horizon will be required to see the conjunction and the early evening sky will be bright just after the Sun has set.

Jupiter and Saturn will not be any closer to each other than they normally are and will still be moving around their established orbits. This conjunction is just a ‘line of sight' effect from our point of view on Earth. The two planets will actually be as far apart from each other as Earth is from Jupiter (about 750 million kilometres). Jupiter is approaching Saturn as it is moving faster than Saturn along its orbital path and will overtake Saturn on 21st December. From our point of view they will appear very close together so at this time the two planets will be at their closest conjunction.

Jupiter and Saturn at their closest conjunction

The chart above shows how the two planets and their moons will appear using a telescope around the 21st December. They should fit into the field of view of most small telescopes and some larger telescopes using a low power eyepiece.

Like all astronomical events the weather will need to be kind to us and we will need a clear view towards the western horizon. The conjunction will unfortunately also be in the still bright sky after sunset.

THE REST OF THE SOLAR SYSTEM NOVEMBER 2020

The mid month sky at 22:00 showing the positions of Mars, Uranus and Neptune

URANUS will not be easy to see as it will be close to the southern horizon. It will rise at about 15:30 and be visible for the rest of the night. Uranus was at opposition on the 31st October. This month it will be due south and at its best at 22:40 but will need a telescope to see it.

NEPTUNE will rise at about 14:00 but will not be easy to observe this month it will be due south at about 19:30. It does require a medium sized telescope to see well.

 

THE SUN

The Sun rises at about 07:00 at the beginning of the month and 06:40 at the end. It sets at 18:20 at the beginning of the month and 16:40 at the end.

A small Sunspot was visible during the middle of October and the picture below was taken on 19th October by the Solar and Heliospheric Observatory (SOHO). This may be the first sunspot as we move into the ‘build up' to the next maximum of the Sun's 11 year cycle of increased activity. The Sun has been passing through its period of low activity over the last year or two and the previous Maximum was rather sparse and disappointing .

The image on the right shows a group of sunspots downloaded from SOHO on 26th October.

Sunspot from SOHO on 19th October

Sunspots from SOHO on 26th October

Sunspots are caused by the strong magnetic field of the Sun. We can think of the Sun being like a gigantic magnet with lines of magnetic force linking the North Pole to the South Pole. However the Sun is not solid as it is mainly comprised of Hydrogen gas and is fluid.

The equatorial region actually rotates faster than the Polar Regions. Consequentially the lines of magnetic force are dragged out and distorted around the equator. Over a period of about five years the lines of magnetic force become tangled and begin to break up.

Where the lines of magnetic force interact with the surface of the Sun a cavity is created where a lower and cooler layer is exposed. As this lower layer is cooler it is less bright and appears darker hence the Sun Spot.

This build-up of magnetic forces has a cycle of about 11 years so we see increased and decreased solar activity over periods of about 5½ years. We are currently about to begin a period of increasing activity so we should be starting to see more Sunspots.

Any activity on the Sun can be followed live using the day to day images of the Sun in detail by visiting the SOHO website at: http://sohowww.nascom.nasa.gov/ .

 

THE MOON PHASES DURING NOVEMBER

There will be a partial Lunar Eclipse on 30th November but it will not be visible from Southern England.

Last Quarter will be on 8th November

New Moon will be on 15th November

First Quarter will be on 22nd November

Full Moon will be on 30th November

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