Description

Northern Hemisphere

The Night Sky

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

The Planets

• Jupiter - Jupiter can be seen low in the west soon after sunset at the start of the month. It shines at magnitude -1.8 (falling to -1.7 during the month) and has a disk some 32.6 (falling to 31.4) arc seconds across. Jupiter's equatorial bands, sometimes the Great Red Spot and up to four of its Gallilean moons could be visible in a small telescope but its low elevation will greatly hinder our view.
  
• Saturn - Saturn will be visible in the south-east at an elevation of ~14 degrees after sunset at the beginning of October. Its disk has an angular size of 16.5 arc seconds falling to 15.7 during the month. Its brightness reduces from +0.5 to +0.6 magnitudes as the month progresses. The rings were at their widest last year but are still well open and spanning ~2.5 times the size of Saturn's globe. Saturn is moving slowly eastwards in Sagittarius. Sadly, atmospheric dispersion will greatly hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.
  
• Mercury - Mercury (shining at magnitude -0.2 and with an angular diameter of ~6 arc seconds) might just be spotted very low in the west at the very end of the month and binoculars could well be needed - but please do not use them until after the Sun has set. Look up and to the left of where the Sun has set as its angular separation from the Sun is not great.
  
• Mars - Mars, now racing eastwards in Capricornus, made its closest approach to Earth since 2003 on the night of July 30th/31st. It can be seen due south shining at a magnitude of -1.3 around 9 pm at the start of October but this falls to -0.6 by month's end when it is due south at ~8 pm. Its angular size is 16 arc seconds at the start of October but this falls to 12 arc seconds by November. With a small telescope it should 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? A superb program WinJUPOS can be used to find what should be visible on any night.
  
• Venus - Venus is not visible from the UK this month but will be seen low in the east just before sunrise by the middle of next month.
  

Highlights

• October - still worth observing Mars. Mars came to its closest opposition to Earth since 2003 on the 27th July but, sadly its elevation has conspired to limit our views. From the UK its maximum elevation when on the meridian is only 14 degrees when observed from a latitude of +52 degrees. It angular size at the start of October is still 16 arc seconds so it is still worth looking for details on the surface now that the dust storm that covered much of the surface in June and July has subsided. The free program WinJUPOS will show you what should be visible on the Martian surface.
  
• October - a good month to observe Uranus with binoculars or a small telescope. Uranus comes into opposition - when it is nearest the Earth - on the 23rd of October, so will be well placed both this month and next. Its magnitude is +5.7 so Uranus, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aries close to the borders of Cetus and Pisces. It rises to an elevation of ~47 degrees when due south. Given a small telescope it will appear as a small turquoise coloured disk. On the night of closest approach, it will lie up to the left of a near Full Moon - whose glare might make it hard to spot!
  
• October - still a good month to observe Neptune with a small telescope. Neptune came into opposition - when it is nearest the Earth - on the 7th of September, so will still be well placed this month. Its magnitude is +7.9 so Neptune, with a disk just 2.3 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius up 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 (around New Moon on the 9th) it should even be possible to spot its moon Triton.
  
• October - early morning: find a Comet with binoculars. In the early hours of a clear morning one should be able, using binoculars, to spot the comet Giacobini-Zinner arching across the heavens as shown on the chart. It was discovered by Michael Giacobini in December 1900, but then 're-discovered' by Ernst Zinner 6.5 years later. Its nucleus is about 2 km across.
  
• October - 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!
  
• October 11th - after sunset: Jupiter below a thin crescent Moon. If clear after sunset and given a very low western horizon one should be able to see Jupiter setting in the West down to the left of a very thin crescent Moon. Binoculars might well be needed to cut through the twilight, but please do not use them until after the Sun has set.
  
• October 14th - after sunset: Saturn to the left of a waxing crescent Moon. If clear after sunset and looking southwest, one should be able to see Saturn over to the left of a waxing crescent Moon.
  
• October 18 - evening: Mars close to the first quarter Moon. During the evening of the 18th, Mars, in the south, will be seen close to the third quarter Moon. A nice photo opportunity perhaps?
  
• Learn the Mare on the Moon. Why not use the annotated image of the full Moon to learn the locations of the Moon's Mare. You can see some of them with your unaided eye and binoculars will enable you to spot them all.
  

Southern Hemisphere

We welcome back a familiar voice for our long-term listeners - Haritina Mogosanu from the Carter Research Center in New Zealand speaks about the Southern Hemisphere night sky during October 2018.

Southern Hemisphere

• The Planets. It's been the winter of the planets in the Southern Hemisphere and spring has continued the theme. October is still offering a great chance to see many of the fantastic planetary sights that we've become accustomed to over the winter. The start of October sees the Sun setting just after 7:30 in the evening as the nights are starting to get shorter and daylight savings has made astronomers stay up an hour extra to view the night sky.
  
• Venus, Jupiter and Mercury. The early evening sky is dominated first by Venus and then by Jupiter as darkness falls. Both of the planets start the month in Libra with Venus heading towards the Sun in Virgo by the end of the month. Jupiter is joined by Mercury from the 27 Oct for a few days, though will be a real challenge to see very low on the horizon just after the Sun has set at about 15 degrees so Kiwis will have to head to the coast or climb up some of the high hills to have a chance of a fleeting view of Mercury. Unfortunately the situation is the same for Jupiter, the planet that has been with us since autumn is getting lower and lower in the sky and will make for challenging viewing.
  
• Saturn, Neptune and Mars. Marching up the ecliptic, Saturn is still in Sagittarius and its rings are at a great tilt to view them. A modest telescope and good seeing should reveal the Cassini division. Also in Sagittarius is Pluto, though at a magnitude of 14.3 it's going to be quite a challenge to see unless you've got your hands on a bigger telescope. And at around 0.1 arcseconds across it's only going to look like a faint star. The dominant planet of the night sky remains Mars, in Capricornus, and at -0.7 magnitude by the end of October it is still going to be very bright and easy to spot - even if you've got to put up with a lot of light pollution. By the end of October, Mars is around 114 million kilometres away which is considerably further away than it is at the start of the month which is 89 million kilometres, showing how fast Earth and Mars are separating. The start of the month will be great for viewing Mars - as it will still be close enough to make out some detail. That is if the seeing is right and the dust storm that silenced the rover Opportunity has long subsided (and hopefully we'll hear from Opportunity by October). The evening sky has one more planet for the keen astronomer with binoculars or telescopes and that's Neptune, the eighth planet from the Sun, which we can find in Aquarius. At 7.8 magnitude it will be easy to spot and will appear as a very small bluish disk. Neptune is a long way away at over 4.3 billion kilometres that is 242 light minutes or about four light hours.
  
• Deep Sky Objects. This time of the year is one of my favourite for viewing deep sky objects and a great place to start is with the Southern Cross and work your way up the Milky Way. Or the other way around. To find the Southern Cross, turn away from the ecliptic and just follow the Milky Way all the way to the two pointers, Alpha and Beta Centauri. We are so lucky in here that we can see the Milky Way. There are some great nebulae in it and really beautiful open clusters. In the Southern Cross is one of the most fantastic clusters in the night sky, the Jewel Box Cluster (also known as NGC 4755). This great little cluster has three stars in a line that look a bit like a traffic light, two blue and one red in the middle. The reddish looking star is a red supergiant about 19 times the mass of the Sun. To the right of the Southern Cross is the huge Omega Centauri globular cluster, which at a magnitude of 3.7 can be seen by the naked eye. Omega centauri is the competitor to 47 Tucanae globular cluster, which is not located in the Milky Way but in Toucana in the south celestial circumpolar part of the sky along with the Magellanic Clouds. Back to the Milky Way, and following up past Alpha Centauri, there's the sting of Scorpius which is home to the Cat's Paw Nebula (also known as NGC 6334). It's quite faint but some of the nebula can be seen - astrophotographers will get a lot of detail. Just up the Milky Way from the sting is M7, also known as Ptolemy Cluster. This amazing cluster is visible with the naked eye but through a reasonable telescope it's very impressive against the backdrop of the star clouds. The cluster has about 80 stars in it. Towards the horizon from M7 is the other amazing Southern Hemisphere site, the Milky Way Kiwi.
  
• Milky Way Kiwi. Right at the center of the Milky Way, a spectacular bird guards the center of our galaxy. This is the Milky Way Kiwi, a shape made from dark dust within our own galaxy. More than ten years ago astrophotographers from New Zealand were taking snapshots of the night sky. One of them looked at the pictures and realised that the dark patch known in the Northern Hemisphere as the dark horse, being upside down here, looked just like a great galactic kiwi bird. But as I realised later while travelling, you either have to be from New Zealand or have friends in New Zealand to know what a kiwi bird looks like. The Milky Way Kiwi is my absolute favourite object in the sky and I once saw it with the naked eye from Lake Tekapo in the South Island. And if you were wondering, the direction of the supermassive black hole at the centre of our galaxy is right on the top of the head of the Milky Way kiwi, just like a jewel on a crown .
  
• The Moon. Since I talked about my favourite object in the sky, the Milky Way Kiwi, I will also mention my least favourite object in the sky, the Moon because it casts too much light at night, but hey people drove on it so that actually makes the Moon very cool apart from the light situation. The Moon here is obviously upside down to the Northern hemisphere and according to New Zealand kids has a big rabbit inside it. You can see its ears are Mare Fecunditatis and Mare Nectaris the head is Mare Tranquillitatis and the tummy is Mare Serenitatis. Behold the rabbit hole at Mare Crisium. Not only that there is this rabbit inside the Moon but the Moon itself is to be found on the northern part of the sky as everything else near the ecliptic in this hemisphere, and facing the ecliptic, east is to the right and west is to the left. That makes the shadows in the morning look like the evening shadows from the other hemisphere and it feels like morning in the evening and evening in the morning until the brain engages back. So if you ever come visit us, don't let them tell you it's only jetlag.
  
• This concludes our Jodcast for October 2018 from Space Place at Carter Observatory. Thank you to the amazing Sam Leske of Milky Way Kiwi who contributed to the content. Good night and have a great October.