The Night Sky This Month

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Ian Morison tells you what can be seen in the night sky this month.
Updated: 5 hours 55 min ago

The night sky for September 2018

Fri, 14/09/2018 - 16:00
Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during September 2018.

The Planets

  • Jupiter - Jupiter can be seen in the west soon after sunset at the start of the month. It shines at magnitude -1.9 (falling to -1.8 during the month) and has a disk some 35 (falling to 33) arc seconds across. Jupiter's equatorial bands, sometimes the Great Red Spot and up to four of its Gallilean moons will be visible in a small telescope. Sadly, moving slowly eastwards in Libra during the month, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of ~10 degrees after sunset. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Saturn - Saturn will be visible in the south at an elevation of ~14 degrees after sunset at the beginning of September. Its disk has an angular size of 17.5 arc seconds falling to 16.5 during the month. Its brightness reduces from +0.4 to +0.5 magnitudes as the month progresses. The rings were at their widest some months ago and are still, at 25 degrees to the line of sight, well open and spanning ~2.5 times the size of Saturn's globe. Saturn, lying in Sagittarius, halts its retrograde motion on the 6th within a few degrees of M8, the Lagoon Nebula, and M20, the Trifid Nebula. Sadly, atmospheric dispersion will greatly hinder our view and, as for Jupiter, it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Mercury - Mercury can be seen low in the east-northeast some 30 to 45 minutes before sunrise during the first week of September. On the 5th and 6th, Mercury, shining at magnitude -1, is just over one degree from Regulus in Leo (at magnitude +1). Around the 11th of the month Mercury disappears into the Sun's glare as it moves towards superior conjunction (behind the Sun) on the 20th of the month.

  • Mars - Mars, which ceased it retrograde motion westwards in Capricornus (and just moving into Sagittarius) at the beginning of the month made its closest approach to Earth since 2003 on the night of July 30th/31st. After sunset, Mars can be seen just east of south shining at a magnitude of -2.1 but this falls to -1.3 by month's end. Its angular size is 21 arc seconds at the start of the month falling to 16 arc seconds by the start of October. With a small telescope it should (but see below) be possible to spot details, such as Syrtis Major, on its salmon-pink surface. From the UK, it will only reach an elevation of ~14 degrees when due south and so, sadly, the atmosphere will hinder our view. Another reason for purchasing a ZWO Atmospheric Dispersion corrector? As I write this in August, the dust storm which has obscured much of the surface since the end of June appears to be subsiding so let's hope it clears during September.

  • Venus - Venus, was at greatest elongation east on the 17th August but is now only seen low in the west southwest after sunset setting at about 80 (reducing to 45) minutes after the Sun. The planet brightens from -4.6 to a dazzling -4.8 magnitudes making it easier to spot in the Sun's glare. Binoculars might be needed to spot it but please do not use them until after the Sun has set. Its angular size increases from 29 to 46 arc seconds during the month as the percentage illuminated disk (its phase) narrows from 40% to just 17%.

  • Highlights
  • Early September - observe Mars. Mars came to its closest opposition to Earth since 2003 on the 27th July but, sadly two things have conspired to limit our views. From the UK its maximum elevation when on the meridian was only 12 degrees when observed from a latitude of +52 degrees. Thus the atmosphere has hindered our view and the use of an Atmospheric Dispersion Corrector may well help to alleviate its effects. The second problem was that, as sometimes happens, Mars has suffered a major dust storm which, at the end of July, was making it very difficult to observe any features on the surface. These can happen every six to eight years and can last for several months. A small scale dust storm began on May 30th and, by the 20th of June, had engulfed the whole planet. Happily, the dust storm has now subsided and so details on the surface such as Syrtis Major and the Hellas Basin will be visible in small telescopes.

  • Early September - observe Saturn. Saturn which reached opposition on the 27th of June, is now low (at an elevation of ~14 degrees) in the south as darkness falls lying above the 'teapot' of Sagittarius. Held steady, binoculars should enable you to see Saturn's brightest moon, Titan, at magnitude 8.2. A small telescope will show the rings with magnifications of x25 or more and one of 6-8 inches aperture with a magnification of ~x200 coupled with a night of good "seeing" (when the atmosphere is calm) will show Saturn and its beautiful ring system in its full glory. As Saturn rotates quickly with a day of just 10 and a half hours, its equator bulges slightly and so it appears a little "squashed". Like Jupiter, it does show belts but their colours are muted in comparison. The thing that makes Saturn stand out is, of course, its ring system. The two outermost rings, A and B, are separated by a gap called Cassini's Division which should be visible in a telescope of 4 or more inches aperture if seeing conditions are good. Lying within the B ring, but far less bright and difficult to spot, is the C or Crepe Ring. Due to the orientation of Saturn's rotation axis of 27 degrees with respect to the plane of the solar system, the orientation of the rings as seen by us changes as it orbits the Sun and twice each orbit they lie edge on to us and so can hardly be seen. This last happened in 2009 and they are currently at an angle of 26 degrees to the line of sight. The rings will continue to narrow until March 2025 when they will appear edge-on again.

  • September - evenings: - Find the globular cluster in Hercules and spot the "Double-double" in Lyra. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!

  • September - evenings: - A good month to observe Neptune with a small telescope. Neptune comes into opposition - when it is nearest the Earth - on the 7th of September, so will be well placed both this month and next. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius over to the left of Lambda Aquarii as shown on the charts. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. (This is my objective around this month!)

  • September - evening: find the 'Coathanger'. Looking upwards after dark you should spot the three stars making up the 'Summer Triangle'. The lowest is Altair in Aquilla, up to its right is Vega in Lyra and over to its left is Deneb in Cygnus. With binoculars sweep upwards about one third of the way from Altair towards Vega. You should spot a nice asterism, formally 'Brocchi's Cluster' but usually called the Coathanger. It is formed of a straight line of six stars below which is a 'hook' of four stars. A pretty object!

  • September first week - after sunset: three planets towards the south and west. If clear after sunset one should be able to see Jupiter setting in the West, Saturn lying due South, and Mars in the South southeast.

  • September 8th - before dawn: Mercury below a thin crescent Moon. If clear before dawn on the 8th, look for Mercury low in the east just below a thin crescent Moon. Binoculars might be needed but please do not use them after the Sun has risen.

  • September 17th - early evening: Saturn below a first quarter Moon. This evening, if clear, Saturn will be seen just below a first quarter Moon - a nice photo opportunity!

  • September 18th - evening: Mars to the lower left of a waxing gibbous Moon. This evening, if clear, Mars will be seen down to the left of a waxing gibbous Moon.

  • September 29th - late evening : the Moon amongst the Hyades Cluster. As Taurus rises, one should be able to spot (if clear!) a waning gibbous Moon amongst the Hyades Cluster.

  • September 18th: Mons Piton and Cassini. Best seen after First Quarter, Mons Piton is an isolated lunar mountain located in the eastern part of Mare Imbrium, south-east of the crater Plato and west of the crater Cassini. It has a diameter of 25 km and a height of 2.3 km. Its height was determined by the length of the shadow it casts. Cassini is a 57km crater that has been flooded with lava. The crater floor has then been impacted many times and holds within its borders two significant craters, Cassini A, the larger and Cassini B. North of Mons Piton can be seen a rift through the Alpine Mountains (Montes Alpes). Around 166 km long it has a thin rille along its center. I have never seen it, but have been able to image it as seen in the lunar section (The 8 day old Moon).

  • In her final Night Sky segment, Gaby Perez from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during September 2018.

    • Introduction - Kia Ora everyone, Gabriela here from Wellington New Zealand looking up at our September Southern hemisphere night sky. We are finally seeing the end of the cold nights as we move into Spring. September is the time for Spring and we can see it in our gardens as well as our skies. Throughout the month you will notice that your days are slowly becoming longer and your nights will be getting shorter as the 22nd of September is the Spring Equinox, meaning that we will have nearly equal amounts of day and night and the days will continue to get longer as we move forward in time.

    • The Planets - We will also notice some change in the elevation of the Sun as it has started appearing higher in our north sky and will continue to move higher throughout the month. In terms of the Moon, new moon will fall on the 9th so the beginning of the month will have the darkest skies which is perfect for viewing all the deep sky objects and the Moon will be full on the 25th of September. We still have quite a few planets in the sky found across the ecliptic. We have four naked-eye planets in our sky. The brightest of these will be Venus, our evening star. It will be on the western horizon shortly after sunset. Above Venus you will find Jupiter and up ahead, east of the zenith we have Mars. All three will be visible just after sunset as these planets appear very brightly in our sky. Mars has been especially bright this year, coming the closest it has to Earth in 15 years at the end of July and is still looking quite bright, about the same brightness as Jupiter but it is now moving away and will be appearing smaller in our skies. As the night gets darker we will see Saturn appearing in the North. The moon will be weaving its way through the planets throughout the month.

    • Scorpius/Antares - Between Jupiter and Saturn you can find our 'winter' constellation Scorpius and its bright orange star, Antares (the rival of Mars). This giant red star marks the heart of the scorpion. But we don't have Scorpions in New Zealand so early Maori see it as a fish hook. And Antares is the bloody bait on the hook. Now Maori constellations, unlike European ones, change as the night changes or as the year does as they will appear at different angles and different locations. For example in the morning, Scorpius will appear on the horizon, hook side up. Then this shape becomes the Western 'Pou' or pillar holding up the sky. It is hooked over as it bears the heavy sky on it's back all alone in the west but in the east there are three 'pou'.

    • Bootes /Argo Navis - We have another brilliant star in our sky. Arcturus, the brightest star in the constellation of Bootes, the fourth-brightest in the night sky, and will appear in our northwest sky with Canopus, the second brightest star on the south skyline. Both of these stars will appear to twinkle. Canopus can look a little like a traffic light as it flashes different colours and Arcturus will flash red and green. This happens when the stars are so close to the horizon and the light scatters and disperses as the light has to travel through a thicker atmosphere before it reaches our eyes. Canopus is in the constellation of Carina which is circumpolar to us here in New Zealand meaning we can see it at any time of the year and night. It was once a part of a bigger constellation, the Argo Navis. that has been split into the three. The giant boat, once the largest constellation, is now formed of Carina (the keel of the ship), Vela (the sails) and Puppis (the poop deck). Carina is found near the Southern Cross (Crux). Through a pair of binoculars you can spot Eta Carinae. A star which once shone brightly in our skies during an event known as 'an imposter supernova'. A supernova can happens at the end of star's life as it collapses in on itself in a massive explosion bursting out bits of gas and dust. Eta Carinae went through a similar event but has not come to the end of its life, it is still quite hardy. Now astronomers are keeping their eye on this star as it may go full supernova are maybe go through another similar event. It is now encased in a nebula and astronomers believe it to be a double star system.

    • Southern Cross.The Southern Cross is easily spotted in the South using the pointer stars, Alpha and Beta Centauri point down to the Crux constellation. Also in the South we have a stunning new of our Milky Way galaxy, the bulge appearing between Scorpius and Sagittarius, marks the heart of our Milky Way.

    • On moonless evenings in a dark sky the Zodiacal Light is visible in the west. It makes up faint light surrounding Venus and Jupiter. It is just sunlight reflecting off meteoric dust in the plane of the solar system. The dust may have come from a big comet, long ago. That will certainly be a sight to see!

    • That's it from me here in Wellington, New Zealand. I wish you all clear skies and a fantastic Spring!

The night sky for August 2018

Tue, 07/08/2018 - 10:00
Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during August 2018.

The Planets

  • Jupiter - Jupiter can be seen in the southwest soon after sunset at the start of the month. It shines at magnitude -2.1 (falling to -1.9 during the month) and has a disk some 38 (falling to 35) arc seconds across. Jupiter's equatorial bands, sometimes the Great Red Spot and up to four of its Gallilean moons will be visible in a small telescope. Sadly, now moving slowly eastwards in Libra, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of ~15 degrees after sunset. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Saturn - Saturn was at opposition on the 27th of June and so will be visible in the south at an elevation of ~15 degrees after sunset at the beginning of August. Its disk has an angular size of 18 arc seconds falling to 17 during the month. Its brightness reduces from +0.2 to +0.4 magnitudes as the month progresses. The rings were at their widest some months ago and are still, at 26 degrees to the line of sight, well open and spanning some 2.5 times the size of Saturn's globe. Saturn, lying in Sagittarius, is close to the topmost star of the 'teapot' slowly moving in retrograde to within a few degrees of M8, the Lagoon Nebula, and M20, the Triffid Nebula. Sadly, atmospheric dispersion will thus greatly hinder our view and, as for Jupiter, it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Mercury - Mercury, having passed between the Earth and Sun (inferior conjunction) on August 9th, becomes visible after the 20th before reaching greatest elongation east of the Sun on August 26th. Then, some 18 degrees from the Sun, it rises before 5 am shining at magnitude zero.

  • Mars - Mars, moving in retrograde motion westwards in Capricornus at the start of the month, made its closest approach to Earth since 2003 on the night of July 30th/31st. It moves into Sagittarius on the 23rd of August. Mars begins the month rising just after sunset shining at its peak magnitude of -2.8 but this falls to -2.2 by month's end. Its angular size exceeds 24 arc seconds until August 8th and falls to 21 arc seconds by the start of September. With a small telescope it should (but see below) be possible to spot details, such as Syrtis Major, on its salmon-pink surface. From the UK, it will only reach an elevation of ~14 degrees when due south and so, sadly, the atmosphere will hinder our view. Another reason for purchasing a ZWO Atmospheric Dispersion corrector? As I write this in July, a dust storm obscures much of the surface - let's hope it clears during August.

  • Venus - Venus, can be seen low in the west after nightfall sinking towards the horizon as the month progresses. During August, its illuminated phase thins from ~57% to ~29% but, at the same time, the angular diameter of its disk increases from 20 to 29 arc seconds. The surface area reflecting the Sun's light does and so the brightness increases from -4.3 to an outstanding -4.6 magnitudes. Venus moves towards Spica in Virgo as August progresses and ends the month just one degree below the star. Sadly, however, they are then only ~10 degrees above the western horizon after sunset.

  • Highlights
  • August - observe Mars.Mars came to its closest opposition to Earth since 2003 on the 27th July but, sadly two things conspire to limit our views. From the UK its maximum elevation when on the meridian will be only 12 degrees when observed from a latitude of +52 degrees. Thus the atmosphere will hinder our view and the use of an Atmospheric Dispersion Corrector may well help to alleviate its effects. The second problem is that, as sometimes happens, Mars is now suffering a major dust storm which, at the end of July, was making it very difficult to observe any features on the surface. These can happen every six to eight years and can last for several months. A small scale dust storm began on May 30th and, by the 20th of June, had engulfed the whole planet. Sadly, it could take as long as September for the dust to settle thus greatly inhibiting our view of Mars this apparation. However, it does look as though the South Polar Cap is still visible. Let's just hope that the dust storm subsides in time for other details on the surface such as Syrtis Major and the Hellas Basin to become visible in small telescopes. On the night of August 11th, these should be facing the Earth. A superb program, WinJUPOS can be downloaded for free and will give a view of Mar's surface for any time, showing what features should be visible.

  • August - observe Saturn.Saturn reached opposition on the 27th of June, so is now low (at an elevation of ~14 degrees) in the west-southwest as darkness falls lying above the 'teapot' of Sagittarius. Held steady, binoculars should enable you to see Saturn's brightest moon, Titan, at magnitude 8.2. A small telescope will show the rings with magnifications of x25 or more and one of 6-8 inches aperture with a magnification of ~x200 coupled with a night of good "seeing" (when the atmosphere is calm) will show Saturn and its beautiful ring system in its full glory.

  • As Saturn rotates quickly with a day of just 10 and a half hours, its equator bulges slightly and so it appears a little "squashed". Like Jupiter, it does show belts but their colours are muted in comparison.The thing that makes Saturn stand out is, of course, its ring system. The two outermost rings, A and B, are separated by a gap called Cassini's Division which should be visible in a telescope of 4 or more inches aperture if seeing conditions are good. Lying within the B ring, but far less bright and difficult to spot, is the C or Crepe Ring.

  • Due to the orientation of Saturn's rotation axis of 27 degrees with respect to the plane of the solar system, the orientation of the rings as seen by us changes as it orbits the Sun and twice each orbit they lie edge on to us and so can hardly be seen. This last happened in 2009 and they are currently at an angle of 26 degrees to the line of sight. The rings will continue to narrow until March 2025 when they will appear edge-on again.

  • August- Find the globular cluster in Hercules and spot the "Double-double" in Lyra. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!

  • August - A good month to observe Neptune with a small telescope. Neptune comes into opposition - when it is nearest the Earth - on the 7th of September, so will be well placed to observe both this month and next. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius to the left of Lambda Aquarius as shown on the chart. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. (This is my objective around the end of the month!)

  • The mornings of August 12th and 13th - midnight to dawn: look out for the Perseid meteor shower - with no Moon in the sky! If clear, these mornings should give us a chance of observing the Perseid meteor shower - produced by debris from the comet Swift-Tuttle. The early morning of the 12th August will give us the best chance, if clear, of viewing the shower, but the peak is quite broad and so it is well worth observing on the nights before and after. Post midnight is best as then Perseus has then risen higher in the sky. Most meteors are seen looking about 50 degrees from the "radiant" which lies between Perseus and Cassiopeia. This year, the Moon is just after 'New Moon' (on the 11th) so will not hinder out view. NB: As we need to view a very wide area of sky, normal binoculars would be of no use, but the Vixen SG 2.1 x 42 that I have just reviewed in the Astronomy Digest, could be useful as it covers a field of view of 27 degrees. Do get to as dark a sky location as you can to the south of any major towns or cities. This dark sky map gives a very good guide to where to travel to.

  • August 14th - Venus just below a thin crescent Moon.After sunset on the 14th, look for Venus, low in the west just below a thin waxing crescent Moon.

  • August 31st - Venus just below Spica, Alpha Virginis. Soon after sunset and looking very low on the west-southwest you might be able to spot Venus just one degree below Spica. Binoculars may well be needed to lessen the light remaining in the sky, but please do not use them until after the Sun has set.

Gaby Perez from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during August 2018.

  • Introduction.Kia Ora, Gabriela Perez here from Space Place at the Carter Observatory in Wellington, New Zealand. We are looking up at the month of August. The worst of winter is now behind us and our nights are getting shorter, but we still have plenty of long nights to look up at the stars. There are some spectacular sights in the sky this month. We have four visible planets in our skies in the early evening. They are so bright, they are outshining the surrounding stars and they become the focus point scattered across the night sky on the arch of the ecliptic backdropped by the zodiac constellations.

  • Venus.Our evening star in the northwest is the brilliant planet, Venus. Because of its thick atmosphere it reflects a lot of light from the sun. It's so bright you will see it first in the sky before the Sun sets. High up in the north you will see Jupiter and following it is the planet Saturn followed by Mars. Mars is rivalling Venus's intensity in the East looking especially bright and red. It is still quite close to the earth as it was in opposition at the end of July and in the beginning of August it will continue to be the closest it has been to earth since 2003 a mere 58 million km from us.

  • Scorpius and deep space objects.The most familiar of the constellations in our sky will be our 'winter constellation', Scorpius. It has a hooked tail and bleeding heart, Antares. Antares and the tail make the 'fish-hook of Maui' in Maori starlore, Antares becoming the bloody bait on the hook. Antares is a red giant star: 600 light years away. Scorpius is also home to four deep space object that were among the first to be catalogued by Charles Messier: M4, M6 also known as the Butterfly Cluster; M7, and M80. Below or right of the Scorpion's tail is 'the teapot' made by the brightest stars of Sagittarius. It is upside down in our southern hemisphere view. Saturn is near the teapot's lid. Between Scorpius and Sagittarius, we find the heart of our Milky Way in the 'bulge'. This area designated 'Sagittarius A' is believed to be the location of a supermassive black hole in the center of our home galaxy helping to hold it all together.

  • The best viewing time for the deep sky objects will be mid-month as we will have the new moon the 11th. Full Moon will on the 26th of August.

  • Dark Nebula.Mid-month will be the best time to look over at the South. High up in the Southwest we have the Crux constellation or the Southern Cross. On a dark moonless night away from the city lights, you might spot a dark patch nearby the Crux's second brightest star 'Beta Crucis'. This is the Coalsack Nebula, a famous dark nebula that is only visible because of the strong concentration of starlight we get along the edgewise view of our milky way. Dark nebulae block out the light from far away stars as they are densely packed pillars of frozen dust and gas. The Coalsack Nebula, much like coal itself, will ignite one day and in 3 or 4 million years, become one of the brightest patches in the sky. The Coalsack Nebula is sometimes known as the head of the Moa here in New Zealand, a large extinct flightless bird, and you can track it's long neck, body and feet formed by the other dark nebula you can make out across the Milky Way.

  • Constellations.If you are awake in the early morning you can catch a glimpse of our dawn skies. We will have Orion and Taurus in the east, last month they were telling the tale of Matariki, the Maori New Year. There are some great views of 'The Pot' a small asterism in Orion with the base formed by Orion's belt. With three fainter stars that form the handle. The middle of these is in fact The Great Orion Nebula, a diffuse nebula and the closest stellar nursery to Earth. Here astronomers have witnessed the birth of stars and protoplanetary disk, the disks in which planets are formed around the young stars.

  • That's all from me here in Wellington New Zealand and I wish everyone clear skies during the month of August.

The night sky for July 2018

Tue, 24/07/2018 - 16:00
Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during July 2018.

The Planets

  • Jupiter - Jupiter can be seen due south soon after sunset at the start of the month and over towards the southwest as the month progresses. It shines at magnitude -2.3 (falling to -2.1 during the month) and has a disk some 41.5 (falling to 38) arc seconds across. Jupiter's equatorial bands and sometimes the Great Red Spot (see 'highlights' for the times when it crosses Jupiter's central meridian) and up to four of its Gallilean moons will be visible in a small telescope. Sadly, moving slowly westwards in Libra during the month, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Saturn - Saturn, was at opposition on the 27th of June and so will be visible during all the (few) hours of darkness. It will highest in the south around midnight as July begins and a little earlier by month's end. Its disk has an angular size of 18.4 arc seconds falling to 18.0 during the month. Its brightness reduces from +0.0 to +0.2 magnitudes as the month progresses. The rings were at their widest some months ago and are still, at 26 degrees to the line of sight, well open and spanning ~2.5 times the size of Saturn's globe. Saturn, lying in Sagittarius, is close to the topmost star of the 'teapot' slowly moving in retrograde to within a few degrees of M8, the Lagoon Nebula, and M20, the Trifid Nebula. Sadly, it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view and, as for Jupiter, it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Mercury - Mercury shining at around zeroth magnitude early in the month reaches greatest elongation west of the Sun is on July 12th. It will be then be seen about 15 degrees down to the lower right of Venus but will have dimmed to magnitude +1 by the 17th and then rapidly fade from view into the Sun's glare.

  • Mars - Mars, in Capricornus, is moving in retrograde motion westwards as it moves towards its closest approach to Earth since 2003 on the night of July 30th/31st. Mars begins the month rising about 2 hours after sunset shining at magnitude -2.2 but its brightness peaks at -2.8 during the final week of July. Its angular size reaches 24.3 arc seconds at closest approach but will exceed 24 arc seconds from July 24th until August 8th. With a small telescope it will be possible to spot details, such as Syrtis Major, on its salmon-pink surface. From the UK, it will only reach an elevation of ~14 degrees when due south and so, sadly, the atmosphere will hinder our view. Another reason for purchasing a ZWO Atmospheric Dispersion corrector?

  • Venus - Venus, can be seen low in the west after nightfall sinking towards the horizon as the month progresses. During July, its illuminated phase thins from ~70% to ~57% but, at the same time, the angular diameter of its disk increases from 16 to 20 arc seconds. The surface area reflecting the Sun's light thus stays roughly constant and so the brightness stays at around -4.2. On July 9th Venus is close to Regulus in Leo and on the 15th to a waxing crescent Moon.

Highlights
  • July - still a great month to view Jupiter. This is a still a great month to observe Jupiter which came into opposition on May 8th and will be visible in the south in the late evening. It is moving down the ecliptic and now lies in Libra so, sadly, will only reach an elevations of ~20 degrees when crossing the meridian. An interesting observation is that the Great Red Spot appears to be diminishing in size. At the beginning of the last century it spanned 40,000 km across but now appears to be only ~16,500 km across - less than half the size. It used to be said that 3 Earths could fit within it, but now it is only one. The shrinking rate appears to be accelerating and observations indicate that it is now reducing in size by ~580 miles per year. Will it eventually disappear?

  • [I have imaged Jupiter recently and the Red Spot is very prominent and has a lovely orange/red colour. These can be seen in my article 'Imaging Jupiter at Closest Approach' to be found in my Astronomy Digest].The features seen in the Jovian atmosphere have been changing quite significantly over the last few years - for a while the South Equatorial Belt vanished completely (as seen in Damian's image) but has now returned to its normal wide state but is less prominent than the North Equatorial Belt .

  • Saturn in the evening Sky. Saturn is just past opposition, so is now due south and highest in the sky in the late evening. It lies close to the topmost star of the 'Teapot' in Sagittarius. Held steady, binoculars should enable you to see Saturn's brightest moon, Titan, at magnitude 8.2. A small telescope will show the rings with magnifications of x25 or more and one of 6-8 inches aperture with a magnification of ~x200 coupled with a night of good 'seeing' (when the atmosphere is calm) will show Saturn and its beautiful ring system in its full glory. As Saturn rotates quickly with a day of just 10 and a half hours, its equator bulges slightly and so it appears a little 'squashed'. Like Jupiter, it does show belts but their colours are muted in comparison. The thing that makes Saturn stand out is, of course, its ring system. The two outermost rings, A and B, are separated by a gap called Cassini's Division which should be visible in a telescope of 4 or more inches aperture if seeing conditions are good. Lying within the B ring, but far less bright and difficult to spot, is the C or Crepe Ring. Due to the orientation of Saturn's rotation axis of 27 degrees with respect to the plane of the solar system, the orientation of the rings as seen by us changes as it orbits the Sun and twice each orbit they lie edge on to us and so can hardly be seen. This last happened in 2009 and they are now well opened out, currently at an angle of 26 degrees to the line of sight. The ring's orientation is beginning to narrow until, in March 2025, they will appear edge-on again.

  • July - Find the globular cluster in Hercules and spot the "Double-double" in Lyra. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!

  • Early July: A very good time to spot Noctilucent Clouds! Noctilucent clouds, also known as polar mesospheric clouds, are most commonly seen in the deep twilight towards the north from our latitude. They are the highest clouds in the atmosphere at heights of around 80 km or 50 miles. Normally too faint to be seen, they are visible when illuminated by sunlight from below the northern horizon whilst the lower parts of the atmosphere are in shadow. They are not fully understood and are increasing in frequencey, brightness and extent; some think that this might be due to climate change! So on a clear dark night as light is draining from the north western sky long after sunset take a look towards the north and you might just spot them!

  • July 3rd ~2:30 am: Mars and a waning gibbous Moon. In the early morning of the 3rd, Mars will be seen down to the lower left of the gibbous Moon.

  • July 9th - sunset: Venus close to Regulus in Leo. On the 9th, one would, if clear, see Venus shining brightly just up to the right of Regulus in Leo.

  • July 10th before dawn: the Moon in the Hyades Cluster. Before dawn, a thin waning crescent Moon will be seen amongst the Hyades Cluster.

  • July 15th, after sunset: Venus to the left of a very thin crescent Moon. If clear after sunset and given a very low western horizon, you should be able to spot Venus over to the left of a very thin crescent Moon.

  • July 19th after sunset: Jupiter below a waxing Moon. After sunset on the 19th if clear, you should be able to spot Jupiter below a waxing Moon. Alpha Libri is to its lower left.

  • July 24th after sunset: Saturn close to a waxing Moon. After sunset on the 24, Saturn will be seen, if clear, to the lower left of the waxing Moon.

  • July 27th after sunset: a Total Eclipse of the Moon.After sunset on the 27th, if clear, we will be able to observe a totally eclipsed Moon. All times in BST.

  • 8:50 Moon rise on the horizon in the south east.

  • 9:21 Maximum eclipse when the Moon is closest to the centre of the Earth's shadow. (The Umbra)

  • 10:13 Total eclipse ends.

  • 11:19 Partial eclipse ends - the Moon has left the Earth's umbra and lost its red colour.

  • 12:28 Penumbral eclipse ends - the Moon has moved out of eclipse.

Gaby Perez from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during July 2018.

  • Introduction. Kia Ora everyone, the winter continues here in New Zealand and with it come the season of Matariki, the Maori New Year as well as spectacular views of our planets and plenty of hours of night to gaze at the night sky.

  • Planets - All the visible planets will be in our skies during the month of July. Mercury will set with the sun in the West appearing close to the brilliant evening star, Venus. High up in the sky will be the orange Jupiter in the constellation of Libra followed by Saturn in Sagittarius, in the bulge of the Milky Way in the location of the centre of our galaxy, and Mars which will be found in Capricornus. Mars will be the closest it has been to earth since 2003 when we pass by at the end of July.

  • Stars and Constellations - The brightest stars in the night sky, Sirius and Canopus can be found in the Southwest both twinkling as they are close to the horizon. Canopus will appear to change colour as the light is dispersed and appears to separate into separate colours as it closer to the horizon marking itself as the traffic light of our South Skies.

  • In the north we can spot Cancer, the Crab with Leo the Lion, looking a bit more like a coat hanger in his stick figure form. Cancer is the dimmest of the Zodiac constellations. The stars forming a shape of a Y, quite tricky to see with the naked eye as the brightest star in this constellation is only magnitude 3.5. Cancer is home to some famous deep sky objects including M66 and the Beehive Cluster. M66 can be found at the midpoint between Regulus in Leo and Procyon in Canis Minor. It is the oldest 'close' star cluster between 3.5-5 billion years old which is quite incredible as stars generally tend to pull away from their sister stars in an open star cluster quite quickly. And just below it we can see the Beehive Cluster aging at only 600 million years old.

  • Milky Way - In the South we find spectacular views of our Milky Way, peppered with dark patches marking the location of dark nebulas made visible to us because of the high concentration of stars the their subsequent light in the edgewise view of our Milky Way, the most visible of these is the Coalsack Nebula. This densely packed pillar of gas and dust could ignite one day, much like coal itself, as within it our all the right conditions for stars to be born. For now one of the darkest patches in the sky but in a few million years it could be the brightest. Of course you can use this to find the Crux or Southern Cross but a more reliable method would be to use the pointer stars, orange Alpha and blue Beta Centauri. The brightest stars in the constellation of Centaurus. Alpha is a triple star system it's dimmest star being our closest stellar neighbor Proxima Centauri at only 4.2 light years away.

  • Pleiades and Matariki - The heliacal rising of the Pleiades star cluster, Matariki, marks the time of the Maori New Year. The dawn sky has a particular importance to us in New Zealand as it was the dawn sky as opposed to the evening sky that was studied closely by early Maori astronomers. At this time of year the sky is held up by four pillars (Pou), three in the east (Sirius, Pleiades and Orion's Belt) and Scorpius being the lone pillar in the West with a curved back as the weight is crushing down on it. The belt of Orion is easily spotted just before sunrise and points us to Matariki. It is found in the shoulder of the bull in the constellation of Taurus. It is a young star cluster, only 100 million years old, mostly consisting of giant hot blue stars. It is a rare sight to be able to pick out so many stars in an individual cluster in our night sky with the naked eye.

  • That's all from me here in New Zealand.To the New Zealand listeners remember to keep warm and I hope you have a happy Matariki season and I wish everyone clear skies in July.

The night sky for June 2018

Tue, 12/06/2018 - 15:00
Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during June 2018.

The Planets

  • Jupiter.Jupiter reached opposition on May 8th, so will be visible during the evening after darkness has fallen. It shines at magnitude -2.5 (falling to -2.3 during the month) and has a disk some 44 (falling to 41.5) arc seconds across. Jupiter's equatorial bands and sometimes the Great Red Spot (see 'highlights' for the times when it crosses Jupiter's central meridian) and up to four of its Galilean moons will be visible in a small telescope. Sadly, moving slowly westwards in Libra during the month, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

  • Saturn.Saturn, comes into opposition on the 27th of June and so will be visible during all the (few) hours of darkness. Its disk has an angular size of 18.2 arc seconds increasing to 18.4 during the month. Its brightness increases from +0.2 to +0.0 magnitudes as the month progresses. The rings were at their widest some months ago and are still, at 25.7 degrees to the line of sight, well open and spanning ~2.5 times the size of Saturn's globe. Saturn, lying in Sagittarius, is close to the topmost star of the 'teapot'. Sadly, it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view.

  • Mercury.Mercury passes behind the Sun (superior conjunction) on the 5th/6th June but will become visible (at around magnitude -0.7) low in the west after sunset by mid-month. By month's end its magnitude will have dropped to -0.2 and it will set some one and a half hours after the Sun when it will have an angular diameter of 6.5 arc seconds. Greatest elongation west of the Sun is on July 12th.

  • Mars.Mars, in Capricornus, beings its retrograde motion westwards on the 28th June as it moves towards its closest approach to Earth since 2003 in two months time. Mars rises at around midnight BST at the start of the month and around 10:30 pm by month's end. During the month Mars has a magnitude which increases from -1.2 to -2.1 and has an angular size of 15.3 increasing to 20.7 arc seconds so, with a small telescope, it will be possible to spot details, such as Syrtis Major, on its salmon-pink surface. It will only reach an elevation of ~14 degrees before dawn so, sadly, again the atmosphere will hinder our view.

  • Venus.Venus dominates the western sky after sunset, shining brightly at magnitude -3.9 (increasing to -4.1 during month) with an angular size of 13 arc seconds increasing to 15 arc seconds as the month progresses. Venus rises a little higher in the sky during June, initially setting around two and a half hours after the Sun but a little less by month's end as its elevation at sunset stays at around 20 degrees. Venus starts the month in Gemini, not far below and to the left of Pollux, but passes into Cancer on the 11th when, on the 19th and 20th, it lies close to the M44, the Beehive Cluster.

  • Highlights
  • June - a great month to view Jupiter.The features seen in the Jovian atmosphere have been changing quite significantly over the last few years - for a while the South Equatorial Belt vanished completely but has now returned to its normal wide state.

  • June 1st ~2 am: Saturn close to a waning gibbous Moon.In the early hours of the 1st, the waning gibbous Moon will lie just up to the left of Saturn as they cross the meridian. [A good photo opportunity.]

  • June 3rd ~2:30 am: Mars and a waning gibbous Moon.In the early morning of the 3rd, Mars will be seen down to the lower left of the gibbous Moon.

  • June 8th, after sunset: Venus to the lower left of Pollux in Gemini.After sunset on the 8th and given a low western horizon Venus will be seen to lie in Gemini down to the lower left of Pollux.

  • June 16th after sunset: Venus and a very thin crescent MoonAfter sunset, if clear, you may be able to spot a very thin crescent Moon lying over to the left of Venus. With binoculars or a telescope you might be able to see the 'Earthshine' which faintly illuminates the dark part of the lunar disk.

  • June 28th ~2:30 am: Saturn and the Full Moon.In the early morning of the 28th, Saturn will be seen down to the lower left of the Full Moon - a nice photo opportunity.

  • January 22nd/23rdth: Two Great Lunar Craters. These are two great nights (late evening on the 22nd) 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 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 classic "terraced" crater. Both can be seen with binoculars.

  • Gaby Perez from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during June 2018.

  • Introduction.Kia Ora, Gabriela Perez here from Space Place at the Carter Observatory in Wellington, New Zealand. It’s certainly getting colder down here as we approach the winter but the good news is that we have plenty of opportunities to look at our southern skies with all the extra dark hours. June is an incredible month for viewing the visible planets.

  • Solstice.Mid month brings on the winter solstice on the 21st of June which in turn brings the longest night and the shortest day. It will also mean the Sun will be at its lowest elevation for the year.

  • Summer Constellations.The beginning of the month will see the last of our summer constellations low in the western sky along with Sirius, the brightest true star, which will twinkle as in the early evening being found closer to the horizon. This twinkling occurs as the star's light will be dispersed as the atmosphere is denser nearing the horizon and we will see a bit of separation of colour. Rising in the East are some of our winter constellations such as Scorpius and Sagittarius. We don't have scorpions here in New Zealand so Scorpius is seen as the fish hook of Maui, with it's bloody bait, the red giant star Antares. Following Scorpius is Saggitarius and the zone between them, Sag A, marks the heart of our Milky Way. Winter in the Southern Hemisphere is a great time to see this 'bulge' of the Milky Way and in this zone astronomers believe to be a supermassive black hole helping to hold our galaxy together.

  • The Planets.The first planet that will be visible in the sky before the sun has fully set is our 'evening star' Venus, it will be visible in the northwest in the constellation of Gemini and it will set about an hour after the sun. The next bright planet will be Jupiter in the east in the constellation of Libra which will remain in our skies until dawn. At about 9pm Saturn will rise in the southeast in the beginning of the month but will appear earlier and earlier each day in the constellation of Sagittarius. Following that will be the final planet to appear in our night sky which is the red planet Mars and we can find him in the constellation of Capricornus.

  • Winter Constellations.The Southern Cross (Crux) will be at its highest point for the year and Achenar, marking the end of the constellation of Eridanus, the river, will be visible just above the horizon. The mid-point of these two objects marks the South Celestial Pole centre which you can use to find South. You can use Achenar to locate the faint constellation of Tucana, and within it a stunning and visible globular star cluster 47 Tucanae. The second brightest globular cluster out of the 150 that exist in the halo of our Milky Way. The brightest can be spotted using the pointer stars (Alpha Cen and Beta Cen) in the constellation of Centaurus, Omega Centauri.

  • Pleiades.In mid June we will also have a sighting of the Pleiades star cluster in our dawn sky which has special significance in New Zealand as the heliacal rising of this cluster marks the time of the Maori New Year. It is found in the shoulder of the bull in the constellation of Taurus. It is a young star cluster, only 100 million years old, mostly consisting of giant hot blue stars. It is a rare sight to be able to pick out so many stars in an individual cluster in our night sky with the naked eye.

  • Hope everyone keeps warm and enjoys the extra hours of dark skies in the evening for some star gazing.