The Orbit Issue 302 Newsletter of the Worthing Astronomical Society Dec 2015

Forthcoming Meeting Speakers and subjects:

16th December 2015 - Video

Announcements TUESDAY OBSERVING EVENINGS

I am very pleased to inform you that the is operational again. Members evening resume with effect from Tuesday the 15th December from 7.30pm till around 11.00pm and every Tuesday thereafter. If in doubt about the sky conditions I can be reached on 01903 505346 during the day or on the observatory mobile 07754821357. All are welcome.

Further to this members should be aware that at the moment the only person that has access to the observatory is Graham Boots who has fitted a combination lock and is the only person who knows the access code. The Executive Committee has requested that he either provides the access code or replaces the lock with the previous key lock. It is the intent of the Executive Committees to provide training in the use of the observatory for any member wishing to undertake

it. Suitably qualified members would then have unrestricted access to this facility. To avoid any

clash of interests a Booking System will be implemented on the Web Site.

LUNAR OCCULTATION OF ALDEBAREN

On Wednesday 23rd December 2015 the first magnitude orange red giant star Aldebaran will be occulted by the twelve day old moon (almost full) at 18h 10m GMT and reappear at 19h 12m GMT at our location. These times are fairly precise for Worthing.

This event can be observed with the naked eye although binoculars or a small telescope will be useful. Aldebaran is a large it might show a fade before the events of disappearance and gradual brightening at reappearance. Another star in Scorpius called Antares which is a red super giant star and is much bigger has been recorded as showing a fade many times.

The moon will be low in the east. Please telephone me on 01903 505346 if unsure what to expect.

Our chairman attended a conference at the British Library :

New Scientist Live - Instant Expert: Frontiers of

He has kindly provided the meeting notes which are a bit large for Orbit but I have published them on our Web Site http://www.worthingastronomicalsociety.org The link can be found under the Orbit menu.

Almanac

ALMANAC

All times U.T for B.S.T. Add one hour PHENOMENA

Rise and set times are for Worthing December

December / January Day Hour

LUNAR 17th 08 Neptune 3º S of Moon 20th 01 Uranus 1º N of Moon December Date Time Rise Set 22nd 04 Winter solstice 29th 03 Mercury at elongation east 20º First quarter 18th 15.17 12.04 00.19 31st 18 Jupiter 1º N of Moon Perigee 21st 09.01 368,417 km Full Moon 25th 11.11 16.38 07.28 January

January 3rd 19 Mars 1.5º S of Moon 5th 23 Pluto at solar conjunction Last quarter 2nd 05.31 00.02 11.50 7th 00 Venus 3º S of Moon Apogee 2nd 11.53 404,277 km 7th 05 3º S of Moon New Moon 10th 01.31 07.49 17.14 9th 04 Venus 0.1º N of Saturn Perigee 15th 02.10 369,619 km 7th 05 Saturn 3º S of Moon First quarter 16th 23.27 11.08 00.39 10th 18 Mercury 2º S of Moon 14th 14 Mercury at inferior conjunction EARTH 16th 06 Uranus 1º N of Moon

December Sunrise Sunset Minima of Algol

18th 07.59 15.56 December 15th 07.00 18th 03.48 21st 00.36 25th 08.02 16.00 23rd 21.30 26th 18.18

January January 7th 05.30 10th 02.18 12th 23.12 15th 20.00 18th 16.48 2nd 08.03 16.07 10th 08.01 16.16 16th 07.57 16.25 Lunar Occultations Times as at Greenwich U.T.

PLANETS Date Z.C. No Mag Phase U.T. (As at December 17th) December Rises Sets Mag Mercury 09.24 16.52 -0.57 23rd Aldebaran 0.9 Diss 18.10 Evening object quite easily observable into the New Year 23rd Aldebaran 0.9 Reapp 19.12 Venus 04.16 14.01 -4.30 24th 741 5.6 Diss 04.56 Easy morning object throughout this period, ideal period to see it 25th 1029 5.2 Reapp 23.38 Mars 02.05 13.06 +1.40 Early morning object in central Virgo near Spica 29th 1409 5.0 Reapp 03.22 Jupiter 23.27 12.16 -1.92 Morning object in south-eastern Leo, now rising before midnight January Saturn 06.34 15.06 +0.61 Pre-dawn object in Ophiuchus, very close to Venus in early January 12th 3188 5.6 Diss 16.35 Uranus 12.47 01.55 +5.78 16th 219 4.8 Diss 18.44 Early to mid=evening object in southern Pisces 19th 667 5.0 Diss 23.59 Neptune 11.39 22.09 +7.92 20th 669 3.8 Diss 00.15 Evening object in Aquarius 20th 677 4.8 Diss 00.55 Pluto 09.09 17.31 +14.27 Approaching conjunction with the Sun - but invisible to us anyway 20th Aldebaran 0.9 Diss 03.24 20th 806 5.0 Diss 22.59 21st 944 5.9 Diss 18.42

Richard Godley

Phoebe - Saturn’s 9th Largest Moon

Phoebe - Saturn’s 9th Largest Moon By Jay Nair On the 16th of August 1899, astronomer William Henry Pickering discovered Phoebe using photographic plates from the Boyden Observatory near Arequipa in Peru. The plates were actually taken by one DeLisle Stewart, a renowned American astronomer. Phoebe is Saturn’s 9th Moon and was the first target met by the Cassini spacecraft on arrival at the Saturnian System in 2004. So this is the view that Cassini encountered on its arrival.

Pheobe from Cassini.

Phoebe is an irregular satellite of Saturn, which means that it’s orbit is inclined from the plane of its parent planet and in this case, the orbit is retrograde or opposite to Saturn’s direction of rotation. Based on this information, it is postulated that Phoebe was probably a captured Comet which probably originated in the Kuiper Belt. An unusual aspect of this Moon is that it possesses its own ring. This ring is not directly visible; however it is tilted at 27 degrees from the equatorial plane of Saturn and was seen in infrared by the Spitzer Space Telescope. It is understood that the ring was formed from micrometeoroid impacts on to Phoebe.

Artist’s impression of Phoebe’s Ring As can be seen above, this ring can extend to 128 to 207 times the radius of Saturn, which will make it larger than then Saturn’s main rings. At 1/16 the size our own Moon, Phoebe is roughly spherical in shape and has a radius of 214Km, and rotates on its own axis every 9 hours and 16 minutes, with an orbit around Saturn taking 18 months. Most of Saturn’s moons have bright surfaces; however Phoebe exhibits a quite dark appearance with a very low albedo (light reflection) and can be described as lampblack in colour. This has led scientists to believe that Phoebe was probably a captured but this theory has now been discarded as Cassini has detected quantities of ice

Phoebe - Saturn’s 9th Largest Moon below the surface and even carbon dioxide at the surface. Phoebe is heavily cratered indicating large impacts in the past. Some of these craters are up to 80Km across with large walls as high as 16Km. We have already tried to name some of these Craters as can be seen below.

Phoebe’s Craters. It is understood that the surface temperature at Phoebe is -193Deg C. That quite cold, however again there are strong indications of large quantities of ice below the surface. Saturn’s Moons are definitely exciting the “Life Elsewhere” brigade, as we have now discovered definite signs of water, carbon Dioxide and other hydrocarbons on some the Moons. So I believe we should continue the exploration of our Giant Planets and their family of interesting Moons to determine if Earth is or is not the only planet with life. Saturn and its Moons and I would like to wish all readers a Happy Christmas and an Enjoyable and Successful Astronomical Year in 2016.

Jay Nair – Dec 2015.

Proposed Dark Sky Reserve Status in the South Downs Lecture Review

Dan has worked for the South Downs National Park Authority for the last three years and has been very involved in seeking for the South Downs National Park to become a Dark Sky Reserve. Our society is very interested in his project becoming successful as our astronomical observatory is sited in the grounds of Windlesham House School, Washington which is located within the South Downs National Park. This area is already a country side protected zone and has no street lights near our observatory. Our observatory has been at this school since 2005. Both the school and our society have invested heavily in our observatory for the benefit of the pupils. Members and our guests act as volunteers operating the observatory and giving talks on many aspects of astronomy to the pupils.

Dan’s occupation covers many areas including planning, external lighting, conducting various surveys and conservation of wild life generally. His main objective is for our local National Park to achieve Dark Sky status someday. Dan is also an active amateur astronomer and a fellow of the Royal Astronomical Society.

One of the most marvellous sights we humans can experience is the dark starry night sky yet for most of us in the UK, this view is blighted by sky glow from the external lighting systems we employed during the twentieth century. The British Astronomical Association since 1990 has brought about huge changes in respect of street lighting across the entire UK and has made a big difference but this is just the beginning of the Campaign for Dark Skies.

To date there are fifteen sites in the UK that will or have Dark Sky status and eight others in the rest of the world. Many are in remote areas in Scotland and Wales. Exmoor was the first success in 2012.

For regions to qualify there needs to be a core dark area, this is measured for light and needs to be a very dark area surrounded by a buffer zone which needs not to be so dark. There are reliable hand meters to measure darkness which we have already used at our observatory.

Designated regions of dark sky can be quite populated. The South Downs region has one hundred and eighty five parishes, plus public houses, churches, railway stations and petrol stations. It needs to be pollution free, with plenty of tranquillity and to be reasonably quiet with limited noise. Dan will need to prepare a lighting survey which includes both red and blue external lighting and hopes there is more red light and not so much blue light. Dan is working on a management plan and putting together a list of good lighting policies for the South Downs application which is to be submitted in January 2016 and will be heard in June 2016. He will encourage downward lighting rather than horizontal. He is concerned about the large amount of aircraft trails in our area. One frustration is a network of authorities in the area to deal with and many will have to update their various policies. Dan delivered a comprehensive insight to this massive task he and the team have before them. We wish him success. He concluded that if the application fails this time some good will be achieved for a better attempt at later times.

Graham Boots

“Journey to a Black Hole" Speaker Bob Turner F.R.A.S. Bob started his talk by saying that almost everything you may have seen on television or in films about black holes, such as that they are a gateway to another universe, is rubbish. Bob would concentrate on the reality. This would be a realistic journey of the imagination to a black hole and to see what we might find. Where would we find a black hole to journey to? There is one in the centre of our galaxy, as there probably is at the centre of every galaxy, and it is in the direction of Sagittarius. But it is 26,000 light years away. We could try a closer one - V404 Cygni, a mere 7,800 light years away. This is thought to be the nearest but still too far away. But using our imagination Bob could take us through all of the problems we would have to overcome to get there and what would happen once we were there.

Only 10% of what we launch actually makes it into space so our craft would have to be built in Earth orbit or perhaps on the moon. Even doing this we would have to get all the parts we need to our chosen construction location. We would have to consider how best to power the ship and how to get everything into it that we would need for the voyage. A hollow cylindrical shape might be the best choice.

We would have to consider Newton's 3 Laws of Motion to work out how we would start, accelerate, cruise, decelerate, arrive at our destination and align with it. Whatever method of propulsion we use we would need to have sufficient fuel to reach our destination or a means of refuelling en route.

What would be in our way on our journey? There is the asteroid belt, the systems of the outer planets, the Kuiper Belt, the Oort cloud and interstellar space. We know virtually nothing about the last 2 of these. There is plenty of rubbish out in space that we could hit with disastrous consequences.

Radiation levels are high out in space and while we might be able to cope at certain levels, provided we don't mind losing our hair, at higher levels the consequences are lethal as all our vital organs are affected and brain cells killed off.

The effects of kinetic energy are a big problem and would limit our speed to 10% of the speed of light and so it would take 78.000 years to reach V404 Cygni.

Who would fund a return trip that would take 156,000 years? No-one can wait this long for a return on their investment and so this would become a one-way trip lasting 78,000 years. Because of this mission duration we would be looking at a 'generation' ship. The crew at the start of the mission would not live to see the trip completed.

How do you select a crew to become a community in space? Overall numbers would depend on the size of the ship, but how many men and how many women should be selected? Future generations of crew would be born on the ship and live their whole lives on the way. How would we feed ourselves? What would we do with crew members as they develop health problems as they age? We might have to regulate the birth rate.

Future generations might not want to continue the mission their forebears had started. Repairs might need to be carried out. Food mutations might occur. Knowledge would need to be maintained. Divisions between crew members might develop in various ways.

Next Bob asked us to imagine we were getting near to our target black hole and to consider what we would find. We would be at risk from cosmic rays, alpha particles and material falling into the black hole. We would attempt to orbit the black hole at a distance of about one light day for greater safety. V404 Cygni has a companion star orbiting it every 6.5 days. There would be a lot of heat and we wouldn't be able to get near it, but we will imagine that our black hole has no companion.

“Journey to a Black Hole" Speaker Bob Turner F.R.A.S.

We might send an unmanned probe to have a closer look. The probe would speed up due to the gravity of the black hole warping the fabric of space around it. We would see the probe apparently slowing down, stopping, becoming redder and eventually disappearing. Sending the probe will have proved useless and we would end up having to take a closer look ourselves.

We could go to the nearest place to the black hole at which a stable orbit could be maintained. It would however be difficult to get out again from there. Further in towards the black hole the orbit becomes unstable and eventually, once the event horizon has been reached, not even light is able to get out.

We would be bombarded with radiation in wavelengths right across the electromagnetic spectrum, most of which would do us harm, and ultimately kill us. Massive heating in the accretion disk wouldn't help. All our ship's material would be vaporised so it would be totally impossible to get near the black hole. But imagine we could get near it.

The Schwarzschild radius is the radius at which the escape velocity from the surface would equal the speed of light. As we travel in we would see the black hole in front of us and, due to the warping of space around it, we would also see the back of the black hole at the same time.

When we are at 3 times the Schwarzschild limit we would have reached the last place at which we could get out again. At 1.5 times the Schwarzschild limit photons are in a circular orbit so no light gets out and some photons fall in. At the Schwarzschild limit light splits into two. The anti horizon would appear in front of us rather than behind.

At 0.8 times the Schwarzschild limit we would become elongated in the direction of travel and we would be compressed in cross-section. We would only be able to go in one direction and would become infinitely long and have no width. We would see everything red shifted in all directions. We would never see the actual singularity or reach it. Space-time curvature becomes infinite. The singularity is not actually a point but a three-dimensional spatial dimension.

Black holes are perhaps the best-known astronomical objects but the least understood. We don't know what's going on at the centre of the black hole. Nobody does. Fortunately for us, there are none near us. All life would be destroyed before we could get close. Our ship would vaporise and gravity would pull us apart. Black holes are best viewed from afar.

Bob's talk was well appreciated by those who were there and, having had a problem with our laptop, we were grateful to Bob for a swift return to the venue with his own laptop to enable the talk to go ahead.

MEETING REVIEW BY RICHARD GODLEY

Edenbridge & District Astronomers: Invites you to Stargazing Live We will be at the Kent and Surrey Golf and Country Club from 7pm on Friday 15th & 3pm on Saturday 16th January 2016. On Saturday we will be looking at the sun through solar telescopes until dusk when we will change to normal telescopes to look at the Moon, Jupiter and deep sky objects. There will be activities for the children and a raffle. This is a free event, no booking required - just turn up.

Please wrap up warm, and CHECK THE WEATHER before choosing which day to come (you cannot see the sky through clouds!).

Any questions please email: [email protected] Food and drink will be available to purchase from the venue. www.edenbridgeastro.org.uk