Wadhurst Astronomical Society Newsletter January 2020

MEETINGS

COMMITTEE MEETING

Members of the Committee are respectfully reminded that there is a meeting of the Committee at Jim’s house on Tuesday 7th of January starting at 1930.

DECEMBER MEETING

Following an outline of the evenings programme, Phil Berry introduced our speaker, our own Chairman, Brian Mills who continues his look at the important contribution women have made to astronomy.

More About Female Astronomers Brian Mills FRAS

In 2016 Brian told us about the important contribution made by a number of women astronomers and tonight he said he is going to talk about two more, Vera Rubin and Beatrice Tinsley.

But first we were reminded of En Heduanna, who lived more than 4,000 years ago. She used astronomy to predict important occasions such as when to plant crops and even when to get married. Then about 400 AD, Hypatia worked on conical sections, important when looking at planetary orbits and also the shapes of mirrors.

Another important female astronomer was William Herschel’s sister, Caroline, who in her own right discovered a number of comets.

Previously Brian had told us about the ladies who measured photographic plates and catalogued stellar brightnesses for Edward Pickering at Harvard University around the start of the 20th century, notably Henrietta Leavitt, who discovered the relationship between the brightness and period of Cepheid variables providing the yardstick to measure the size of our own galaxy and the distance to others, although at that time women were not even permitted in observatories.

Now Brian introduced us to Vera Rubin.

Vera was born Vera Florence Cooper in Philadelphia in 1928. She became interested in astronomy and at 14 built her own telescope using a cardboard tube that had originally been used to wrap lino around.

1 Vera Ruben with the telescope she had built at the age of 14.

At high school she was told that astronomy was not very lady-like but she did win a scholarship to Vassar College in New York and after three years graduated with a degree in astronomy in 1948. She applied to Princeton University to study astrophysics but was told that women were not allowed to study physics or be taken onto astronomy programmes, but eventually Vera earned a Masters Degree at Cornell University in 1951, having married Bob Rubin also a student there. Her interest was in the velocity of galaxies but we were told that at the time, astronomy was very male-oriented and she found difficulty in finding employment.

In 1952, despite now having a family, Vera was encouraged by her husband to take her PhD so she attended Georgetown University with George Gamow as her doctoral advisor who she described as a bit odd. For her thesis she continued to study galaxies and their distribution and concluded that they tended to clump together although this was rather controversial at the time. She earned her PhD in 1954.

Vera spent a year teaching Maths and Physics followed by 10 years as a lecturer, research astronomer and assistant professor in astronomy at Georgetown.

At one time, she was handed a photographic plate taken by Kent Ford at Mount Wilson Observatory and asked if she could measure the velocities of stars in the galaxy. She said she could and having achieved it was offered a job at Carnegie in the Terrestrial Magnetism department. So much was her recognition in astronomy that she even became officially the first female astronomer to use the Mount Palomar 200-inch telescope.

By measuring the variations in red-shifts of local galaxies including the Milky Way Vera Rubin calculated that they were all moving towards what became known as “The Great Attractor” but she was advised to give the idea up because it couldn’t be true, yet as Brian said, in the 1980s she was proved to be correct.

Because of the controversy, she concentrated on measuring the rotation of spiral galaxies, working with Kent Ford who had designed a new advanced spectrometer. They took a number of plates at various observatories.

Vera Rubin and Kent Ford working together at Lowell Observatory in 1965

Smithsonian Institute

2 Brian said that very quickly it became obvious something was not as expected. In measuring the speed of stars in galaxies, Vera found that the outer stars were orbiting with such velocity that they would be expected to fly apart and away from the galaxy. She suggested that there was something we could not see that was holding the stars together and that probably we were only seeing about 10% of all matter. There must be something present within the galaxies and that has become known as Dark Matter. More recently, measurements suggest that we see about 5% visible matter with about 27% Dark Matter and 68% Dark Energy.

Vera Rubin received many awards such as the national Medal of Science, the Gold Medal of the Royal Astronomical Society and Honorary Doctorates from Yale, Harvard, Grinnell and Princeton.

Smithsonian institute

Vera Rubin died on Christmas Day 2016 aged 88.

The second woman astronomer Brian told us about was Beatrice Tinsley. She was born Beatrice Muriel Hill in Chester, England in 1941 but she and her parents emigrated to New Zealand after the war.

Beatrice Muriel Hill Emigrated to New Zealand with her parents after World War 2

She wanted to take music and maths at school, but was sent to the boy’s school to study the latter. In 1958 she was awarded a scholarship to Canterbury University and chose to study physics.

Beatrice graduated in physics in 1962 and then took a Master’s Degree in crystal structures in magnesium nitrate. At this time she married a fellow student, Brian Tinsley and in 1963 they moved to Dallas in the USA. She enrolled on a PhD course at Austin and received her PhD in 1968.

3 We were told that in her thesis Beatrice stated that the colour of a galaxy depends on how the stars formed and changed as they evolved, so the galaxy changed in brightness and to ignore this would introduce errors into calculations. She also stated that the Universe would expand forever.

Her reputation grew and she was appointed visiting professor at Californian Institute of Technology, the University of Maryland, Yale and Lick observatories but it wasn’t until 1975, following her divorce the previous year that she obtained permanent employment as a Cosmologist – a Theoretical Astrophysicist at Yale which Brian said was exactly the sort of job she wanted.

Her contribution to the formation of galaxies was being recognised more and more. She was the first person to create a computer model of how colour and brightness changed as a galaxy aged and she made accurate predictions of how the interstellar medium was re-cycled.

Beatrice Tinsley at a symposium in 1977

New York Times

1978, Beatrice became the first woman to become a full professor of astronomy at Yale.

Sadly, she was diagnosed with a virulent form of cancer following the discovery of a mole on her leg and she died in March 1981 aged just 40 but we were told that she had even written references for each of her students that they could use after her death.

Beatrice Tinsley received many awards and recognitions. A main belt asteroid 3087 was named after her as was a mountain in New Zealand and in Auckland a street was named in her honour but Brian said one of her greatest accolades was to receive recognition by Google to mark what would have been her 75th birthday!

Following Brian’s talk we had a coffee and tea break with seasonal biscuits, Stollen and mince pies provided by Eva, Jan and Gill with grateful thanks.

Our December meeting wouldn’t be the same without John Wayte’s Christmas Quiz, and he didn’t let us down.

THE CHRISTMAS QUIZ

A popular event at our December meetings is John Wayte’s Christmas Quiz, and John didn’t let us down and provided a number of challenging and not so challenging questions with prizes to be won.

Here are just a few samples of his quiz questions.

1. Which astronomer is best known for his laws of planetary motions?

2. Ariel, Umbriel, Miranda, Titania and Oberon are all moons of which planet?

3. Olympus Mons is a large volcanic mountain on which planet?

4. Name the Russian space station that operated in low Earth orbit from 1986 to 2001?

5. Can you name either of the two moons of Mars?

6. How many moons in total do the four terrestrial planets have?

7. Name the first man made object to leave the Solar System and cross into Interstellar Space?

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8. What unit of length is equal to about 3.26 light-years?

9. Which space probe was the first to orbit another planet?

10. How much of the Milky Way is visible?

a. Less than 5% b. Around 50% c. More than 90%

11. Name the comet that completes an orbit of the Sun approximately once every three years – the shortest period of any known comet?

12. Which planet did Sir William Herschel discover in 1781?

The answers can be found at the end of the newsletter.

JANUARY MEETING

15 January 2020 – There will be a brief Annual General Meeting followed by a talk by Ian King entitled “Remote Astronomy”. Ian runs a remote astronomical telescope in Spain where the skies are far better than we get here in the UK. He intends demonstrating the facility live during the January meeting.

Meetings will take place at Uplands College, Lower High Street, Wadhurst and are held in classrooms IL5 and IL6, which are in the blue walled classroom block at the far end of the drive from the main gate and up by the tennis courts now being used as a temporary building site. Signs will direct you. There is car parking just to the right as you enter the college through the main gates. Alternative free parking is in the town car park next to the Greyhound pub. The Post Code is TN5 6AZ,

Meetings begin at 1930 prompt although members are invited to arrive anytime after 1900, as this is a good time to exchange ideas and discuss problems and also perhaps help set things up before the meeting starts.

Anyone is welcome but visitors are asked for a small fee of £3.

FUTURE MEETINGS

12 February 2020 – (Note: 2nd Wednesday of the month) We have a welcome return by Colin Stuart FRAS who talks about “Rebel Star; the Sun’s Greatest Mysteries”, the subject of his new book.

18 March – The entertaining Dr. David Mannion FRAS regales us with “The Beauty of the Heavens”.

22 April – (Note: 4th Wednesday of the month) Professor David Rees – tells us about ”Black Holes, Gravitational Waves and Horizon Events”.

20 May – Details to follow.

SKY NOTES FOR JANUARY

Planets

Mercury reaches superior conjunction on January 10th at which point it will be on the opposite side of the Sun to the Earth and of course invisible to us. In practice it is rarely true that Mercury is exactly behind the Sun as seen from Earth because what is usually the case is that the planet appears to pass either to the north or south (2° south in this case) of our parent star. This is due to the orbits of all the planets being tilted by small amounts with regard to each other so the line-up is nearly always imprecise. The exception, of course, is at the time of transit when the alignment is exact as we saw last year on November 11th when the tiny disk of Mercury passed slowly across the face of the Sun. The next chance to see such an event will be on November 13th 2032 beginning at 07:20 (sunrise) and concluding at 11:07.

Following superior conjunction Mercury moves to the east of the Sun to make itself available in the evening skies after sunset, reaching greatest elongation on February 10th. However, on the last day of January the planet is almost 10° high in the south west at sunset shining at a respectable magnitude of -1.0. Although its altitude will continue to improve next month its brightness will begin to fall off slightly. Despite this it will still be a moderately good apparition for UK observers. Fig 1 shows the position of Mercury with respect to the horizon and cardinal points throughout January and February 2020.

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Venus is becoming easier to see as its altitude gradually increases. On the 1st it is 18° above the south-south-western horizon at sunset, setting three hours after the Sun, allowing it to be seen in progressively darker skies. The planets brightness is slowly increasing as it moves towards greatest elongation on March 24th and this month attains magnitude -4.1. On January 27th it passes within .08° of the much fainter Neptune and the following day makes a photogenic pairing with 13% waxing crescent Moon. By the end of January Venus presents a 74% gibbous phase, though as the phase shrinks the planets apparent size increases as the distance between our two bodies decreases. It is by far the brightest object in that part of the evening sky, in fact in any part of the evening sky with the exception of the Moon. Venus begins the month in Capricorn, moving north-eastwards into Aquarius on the 11th and almost reaching the border with Pisces by the end of January.

Earth is at perihelion (it’s closest to the Sun) at 07:49 on January 5th 2020. At that moment in time the distance between the two bodies will be 147,091,144 km. This equates to approximately 0.983 AU or 0.983 of the mean distance between the Sun and Earth which is the basis of the astronomical unit (AU).

Mars reached solar conjunction in early September last year and so is now rising more than three hours ahead of the Sun meaning it is 16° high in the south-south-east at the beginning of civil twilight on the first of January. As the month progresses the angle that the plane of the ecliptic makes with the horizon becomes less and less, cancelling out the increased elongation (by 10°) of Mars from the Sun. The red planet spends the first week of January in Libra before its easterly (direct) motion carries it over the border into Scorpio where it remains for just eight days before moving to non-zodiacal Ophiuchus. It spends the remainder of the month there although its movement is rapid. It passes close to NGC 6287, a magnitude +9.3 globular cluster, on January 29th. The brightness and angular size of Mars are both slowly increasing as opposition approaches in October. Fig 2 shows the position of Mars mid-month with the Sun six degrees below the horizon (beginning of civil twilight). At this time the planet passes 5° to the north of the brightest star in Scorpio, whose name, Antares in Greek, means “rival of Mars”. The reddish hue of Antares is obvious so there can be no doubt how it came by that name.

6 Jupiter was at solar conjunction at the end of last month so as the year begins it is very close to the Sun. The apparent easterly motion of the Sun soon opens a gap up between it and the gas giant to the extent that, by the end of January, Jupiter precedes sunrise by over an hour and a quarter when it lies 9° above the south eastern horizon. The planet spends January moving eastwards amongst the stars of Sagittarius, growing in brightness (to magnitude -1.9) and apparent size (to 32.5 arc seconds). Fig 2 shows its position mid-month although it is very low down in the twilight.

Saturn reaches solar conjunction on January 13th and is therefore not available for observation this month. It should become visible as a morning object later in February although it doesn’t have the stand-out brightness that Jupiter does which helps so much when trying to locate an object in a twilight sky.

Lunar Occultations In the table below I’ve listed events for stars down to magnitude 7.5 that mostly occur before midnight although there are many others that are either of fainter stars or occur at more unsociable hours. DD = disappearance at the dark limb, RD = reappearance at the dark limb and RB = reappearance at the bright limb. The column headed “mm” (millimetres) shows the minimum aperture telescope required for each event.

Jan. Time GMT Star Mag Phase % illumination mm Jan 3rd 18:03 SAO 109783 7.3 DD 55 70 Jan 3rd 23:46 ZC 208 7.0 DD 57 90 Jan 4th 16:10 ZC 291 6.8 DD 64 100 Jan 4th 20:33 ZC 306 6.8 DD 65 70 Jan 9th 17:04 ZC 976 2.9 DD 99 40 Jan 12th 00:16 onwards M44, Beehive 3.1 98 40

Phases of the Moon for January

First ¼ Full Last ¼ New Jan 3rd Jan 10th Jan 17th Jan 24th

ISS Below are details for the evening passes of the International Space Station (ISS) this month that are brighter than magnitude -2.0. The details of other passes, including those visible between midnight and dawn, can be found at www.heavens-above.com. Please remember that the times and directions shown below are for when the ISS is at it’s maximum elevation, so you should go out and look at least five minutes beforehand.

Jan. Time GMT Mag. Alt° Az. Jan. Time GMT Mag. Alt° Az. Jan 22nd 18:41:28 -2.3 26° S Jan 28th 18:38:47 -3.9 80° N Jan 23rd 17:53:28 -2.0 20° SE Jan 29th 17:49:52 -3.8 88° N Jan 24th 18:40:55 -3.4 52° SSE Jan 30th 18:37:41 -3.9 81° N Jan 25th 17:52:11 -2.9 38° SSE Jan 31st 17:48:44 -3.8 78° N Jan 26th 18:39:52 -3.9 82° SSE Jan 31st 19:24:16 -2.2 35° W Jan 27th 17:51:00 -3.6 66° SSE

Iridium Flares There are no Iridium flares predicted for evenings in January.

Meteors The Quadrantids are generally seen as ushering in the new season, although activity begins on December 28th and carries on over the New Year until January 12th.

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Peak activity is expected to be seen just before dawn on January 4th so with a 57% Moon having set at 01:00 and the radiant at more than 70° it just needs the weather to cooperate for there to be a really good show. The prediction for the zenithal hourly rate (ZHR) is in the order of 80 under ideal conditions. The best time to look is late at night on the 3rd, when the Moon is low in the sky, though to the early hours of the 4th. Fig 3 gives the location of the radiant close to the “handle” in the plough although it is actually over the border in neighbouring Boӧtes.

Penumbral Eclipse of the Moon There will be a penumbral lunar eclipse on January 10th which occurs in the early evening.

First contact with the penumbral shadow occurs at 17:07:45 (P1) as the Moon begins to move into the outer, fainter, area of shadow that is cast out into space by the Earth. Maximum immersion occurs at 19:11:10 although the northern extremity of the Moon will remain clear of the shadow at all times. Once maximum eclipse has been reached the Moon moves slowly out of the penumbra until by 21:12:19 (P4) it has left the Earth’s shadow entirely.

8 As has been mentioned before, the change in magnitude of the Moon during such events is very small and can easily be missed by a casual glance. There are four penumbral eclipses of the Moon this year although only this one is visible in its entirety from the UK. The others are limited either at moonrise or moonset.

The Night Sky in January (Written for 22.00hrs GMT mid month) In the east Leo has cleared the horizon whilst ahead of it lies the faint and difficult to identify shape of Cancer. The crab contains two easy to locate open clusters: M44 known as the “Beehive” and M67, slightly south of its brighter neighbour. The former is magnitude +3.7 and is about three times the size of the full moon whilst the latter is fainter at magnitude +6.1 and about a third the size of the beehive. Just below Cancer is the head of Hydra (the water snake) although only about half of its body is above the horizon at the present time.

As we turn to the south we see that Orion is on the meridian with his retinue scattered about him. However, there are constellations that abut the hunter that rarely get a mention being overshadowed as they are by their more illustrious neighbours. To the east of Orion is Monoceros the unicorn that is comprised of stars that are mostly 4th and 5th magnitudes. It lies on the galactic plane so there are more than fifty open clusters, with M50 and NGC 2244 being the brightest, but few galaxies. To the south of Orion is the small but easily identified shape of Lepus, the hare. It contains no bright deep sky objects but M79 is a magnitude 8.0 globular cluster that can be seen in binoculars. Finally, to the west of the hunter begins the long winding line of stars that forms Eridanus, the river. Beta Eridani, the second brightest star in the constellation, lies just to the north-west of Rigel and looks as if it ought to be part of the hunter but in fact the boundary, as defined by the International Astronomical Union, passes between the two stars. Above Orion and close to the meridian lies Capella, the brightest star in Auriga, the charioteer that dominates the zenith at this time of year although in the summer it passes just a handful of degrees from the northern horizon.

Looking towards the west we see that despite Pegasus preparing to set M31 in Andromeda is still 40° in altitude. Although one of the fish in Pisces may be setting the other will be visible for some time yet as will the two small constellations close to it, Aries and Triangulum the former of which has the planet Uranus currently within its boundaries.

In the north two members of the Summer Triangle, Deneb and Vega are approaching (but not disappearing below) the horizon although for the latter of the two it will be a very close skirmish. The larger of the two bears is standing on its tail whilst the dragon that winds between them has its head on the meridian below the pole.

Highlights for 2020 January 10th – Penumbral eclipse of the Moon March 18th – early morning conjunction of Mars, Jupiter and the Moon. Saturn is also nearby. June 5th – Penumbral eclipse of the Moon. Eclipse in progress at moonrise. July 5th – Penumbral eclipse of the Moon. Eclipse in progress at moonset. July 14th – Jupiter at opposition. July 20th – Saturn at opposition. August 12th/13th – Perseid meteor shower maximum. Moon rises at midnight. October 13th – Mars at opposition. November 30th – Penumbral eclipse of the Moon. Eclipse in progress at moonset. December 13th/14th – Geminid meteor shower maximum. No interference from moonlight. December 21st – extremely close early evening conjunction of Jupiter and Saturn. The two pass approximately six arc minutes apart. Fig 5 shows the relative positions of the planets as well as their brighter moons and two stars, from the Hipparcos catalogue, that happen to lie in the same line of sight.

Brian Mills FRAS

9 ANSWERS TO THE CHRISTMAS QUIZ

1. Johannes Kepler. Kepler stated three laws. a. Planets move in ellipses with the Sun at one of the focus points b. The radius vector describes equal areas in equal times c. The squares of the periodic times are to each other as the cubes of the mean distance

2. These are Uranus’s five major moons out of a total of 27.

3. Olympus Mons is on the surface of Mars and is something like 2½ times the height of Everest at over 20 km.

Olympus Mons on Mars NASA/JPL image

4. MIR was occupied for a total of 12 years. It replaced the low Earth orbit Salyut space stations and was the first modular space station. MIR was de-orbited with re-entry in 2001.

Russia’s low Earth orbit modular space station MIR

5. Phobos and Deimos are the two moons orbiting Mars. Phobos has a mean diameter of 12.2 km and smaller Deimos has a mean diameter of 12.6 km. They were discovered by Asaph Hall in 1877.

6. Three. Mercury has non, Venus has none, Earth has one and Mars has two.

7. Voyager 1. Voyager 2 was launched first in 1977 to allow flybys of Jupiter, Saturn, Uranus and Neptune. Voyager 1 was launched a couple of weeks later but on a shorter and faster trajectory designed to provide an optimal flyby of Saturn’s moon Titan. Today Voyager 1 is nearing 14 billion miles from Earth and Voyager 2 is just over 12 billion miles away and both have now reached Interstellar Space; Voyager 1 in 2012 and Voyager 2 in 2018.

8. The Parsec, which is about 19 trillion miles and is equal to 6.25 light years. Most professional astronomers prefer to us the Parsec which is defined as the distance at which one Astronomical Unit (The radius of the earth’s orbit round the Sun) subtends and angle of one are-second. Proxima Centauri, our nearest neighbour and is about 1.3 Parsecs away.

10 9. In 1971 Mariner 9 became the first probe to orbit another planet; Mars.

10. Less than 5% of the Milky Way galaxy is visible. The other 90% is made up of Dark Matter and Dark Energy.

11. Encke’s Comet, named after its discoverer Johann Franz Encke in 1786. The comet’s next perihelion is in June 2020.

12. Uranus.

2020 SUBSCRIPTIONS

Subscriptions to the Wadhurst Astronomical Society are due from the 1st of January 2020. At the October Committee meeting it was felt that we could keep our subscriptions unchanged for the coming year. The subscriptions remain at £25 per adult member and £35 for two family members at the same address. Members under 17 years of age and students remain free.

Subscriptions can be paid either by cheque made payable to Wadhurst Astronomical Society or as cash at the meetings or by post to: John Wayte Members Secretary Wadhurst Astronomical Society 27 Pellings Farm Close Crowborough East Sussex TN6 2BF

The Subscriptions can also be paid via electronic banking to: Wadhurst Astronomical Society Account Number 35104139 Sort Code 60-22-15 Putting your name as the Reference so we know who is paying.

CONTACTS

General email address to contact the Committee [email protected]

Chairman - Brian Mills FRAS 01732 832691

Secretary - Phil Berry 01580 291312

Treasurer - John Lutkin

Membership Secretary - John Wayte

Newsletter Editor - Geoff Rathbone 01959 524727

Observing Director - Ian McCartney

Librarian - Phil Berry

Catering Manager - Jim Cooper

SAGAS Representative - Eric Gibson

Wadhurst Astronomical Society website: www.wadhurstastro.co.uk

SAGAS website: www.sagasonline.org.uk

Any material for inclusion in the February 2020 Newsletter should be with the Editor by January 28th 2020

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