Halley's Comet, 1985-86

Roy Cheesman & David Payne

Halley's Comet is named after Edmond Halley. It has a periodicity of approximately 76 years. Records of its observation go back to 690BC. Chinese astronomers recorded Halley's Comet on every apparition for over 2000 years from 240 BC to 1835 AD. (Until 1984, there was a missing observation from the Chinese record: the apparition of 164 BC. However, in 1984 astronomical historians deciphered a Babylonian tablet in the British Museum and found a description of a comet in 164 BC and also one of its next apparition in 87 BC: this had to be Halley's Comet!) Investigation of the Chinese records show that the comet has not faded significantly throughout the last 2000 years. Even now, Halley's Comet is the only bright comet whose apparitions can be predicted accurately.

Halley's Comet, like so many others, has been thought of in historical times as a bringer of doom and destruction. Some of the historical apparitions of Halley's Comet were as follows:

• 66 AD: the comet could have been an omen of the fall of Jerusalem to the Romans.

• 218 AD: the comet's apparition marked the end of the Hun Dynasty, which had ruled China for four centuries.

• 451 AD: the comet was on the side of the Romans at the battle of Chalons where they defeated the armies of Attila the Hun.

• 684 AD: the Ccomet marked three months of rain, crop failure and a terrible plague suffered by Europe.

• 837 AD: the comet's apparition was spectacular as it swept past the Earth on its closest ever approach, at a minimum distance only ten times that of the Moon.

• 1066 AD: William the Conqueror saw a bright comet (which we now know was Halley's Comet). The comet struck terror into the heart of England's King Harold who was killed on the battlefield at Hastings. William's army conquered England and he had an image of the comet embroidered in the Bayeux Tapestry which recorded the story of the conquest.

• 1301 AD: the Florentine artist Giotto de Bandone immortalised the comet when he depicted it as the Star of Bethlehem in his painting of the Adoration of the Magi in the Arena Chapel, Padua.

• 1456 AD: a myth grew up in later years that Pope Callistus III excommunicated the comet in 1456. (In fact, Platina, a contemporary of Pope Callistus III, who wrote a history of the popes, appears to have inadvertently caused the myth. Despite later efforts to dispel the myth, it remains widespread! See www.geocities.com/Athens/Olympus/6745/HCexcomunication.htm for more details.

Short Biography Of Edmund Halley (1656 - 1742)

Click here for a short biography of Edmond Halley.

Observations Of Halley's Comet

During early 1985, a wave of excitement about the prospect of observing Halley's Comet spread through OASI as it did through many astronomical associations. Click here for the notice in the OASI Newsletter of January 1985 inviting members to declare an interest in the available observing expeditions.

In early 1985, the UK 3.5m infrared telescope in Hawaii was first to detect Halley's Comet on its late 20^th Century passage around the Sun. When first detected, the comet was beyond the orbit of Jupiter and was too faint to be directly seen in visible light. However, initial observations indicated that the comet was circa 20km in diameter and already surrounded by a halo of dust despite its distance from the Sun.

At the 1985-86 apparition, the closest approach of the comet to the Earth travelling inbound towards the Sun was on 27 November 1985. The comet's velocity at closest approach inbound was circa 100,000 km/hr. Perihelion was on 09 February 1986, by which time the comet's velocity had increased to circa 150,000 km/hr. The second closest approach, this time leaving from the Sun, was on 11 April 1986, after which the comet receded to the outer regions of the Solar System.

In its 1910 apparition, the head of Halley's Comet expanded to some 450,000 km in diameter and its tail extended to some 30 million km. Unfortunately in its 1985-86 apparition, even had the comet assumed the same dimensions as in 1910, it was poorly placed for observation from the northern hemisphere and would not appear prominent to astronomers situated there. The comet was at its brightest during early April 1986 when it was visible from southern skies: best locations to observe were Southern Africa, Australia, New Zealand and Antarctica. Prior to the event, there were hopes that the Comet's tail might be observed from the northern hemisphere rising above the horizon in mid-April; however, a full moon occurred in mid-April which would seriously hamper such observations. At the end of April 1986 the comet returned to northern skies but was faint as it raced away from the Sun back into deep space. 

The 1985-86 apparition of Halley's Comet was the first which was observed from space as well as from the ground. Table 1 lists the space probes sent to rendezvous with the comet.

Table 1. Space probes scheduled to rendezvous with Halley's Comet.

OASI made its first attempt to find Halley's Comet with the 26cm refractor during the early hours of Sunday 01 September 1985. At the time, the comet lay in Orion, close to the stars 68 Ori and 71 Ori. Unfortunately, the attempt was unsuccessful due to a combination of object too faint, altitude too low, seeing slightly hazy and observers too tired! However, the comet was brightening rapidly (forecast to reach magnitude 12.0 by mid-September) so the observers were enthusiastic about the prospects of securing an observation before too long. The Society as a whole was excited about the prospect, and the committee offered to organise further early-morning observing sessions and proposed a number of observing projects for members to contribute to:

• A photographic record, using both colour and black & white film, following as far as possible the International Halley Watch guidelines.

• Drawings made using the 26cm refractor. This project was particularly relevant to Orwell Park Observatory because drawings made with the 26cm refractor could be compared directly with drawings made using other long-focus refractors of similar vintage at the last apparition in 1910.

The Committee published in the September 1985 Newsletter the following guide to the observation of Halley's Comet (table 2).

Table 2. Observing guide for Halley's Comet.

Following the first attempt at locating Halley's Comet from Orwell Park, the weather in the east of England deteriorated and by 23 September 1985 David Payne (then OASI Chairman) wrote an article in the Newsletter bemoaning the fact that no members of OASI had yet seen Halley's Comet. Fortunately by early October the weather had improved and members of OASI had recorded Halley's Comet photographically from Orwell Park, and one week later several members observed the comet visually. The following extracts from the Newsletter for October 1985 convey something of the excitement of the occasion.

Photographic Recovery Of Halley's Comet,   A J Smith

During early August 1985 it was decided that an attempt should be made to photograph Comet Halley using the Orwell Park 10" refractor. Unfortunately it was not until the night of 4/5 October that weather conditions permitted a sensible try at the much heralded object. Following a few phone calls, three members assembled in the observatory at midnight. Despite a nearly full Moon close to the predicted field, photographic exposures were started at 02:00 UT by two of the members using Ilford HP5 B/W and 1000 ASA colour films.

After development, the 10 minute exposures on both films showed an object in the predicted position. A 10x8 inch print of the HP5 film (rated at 3200 ASA) showed a remarkable lack of background fog and a definite image of the comet.

The following weekend using much clearer skies and no interfering moonlight another attempt was made. Again using HP5 rated at 3200 ASA, a photograph taken with the 10" refractor, guiding on stars in the predicted field (no glimpse of the comet to the eye) produced star images down to mag 12.5 and an object exactly in the predicted position. Subsequently, a comparison with a drawing made by David Payne at the same time using his own telescope showed an object in the same place.

Were these photographs the first of Comet Halley through the 10" Orwell Park Telescope, or did someone else take some 76 years ago at the comet's last apparition? If anyone knows of any other photographic observations of Comet Halley made with the Orwell Park Refractor I would be very glad to hear from them.

Sighted At last, Halley's Comet!   D B Payne

On Saturday 12 August 1985 we had one of the finest nights for some considerable time and it was the first real opportunity since the middle of August for a thorough search for that elusive wanderer, Halley's Comet. I had been away for the previous ten days and hadn't had any contact with other members of the Society, I therefore decided to search with my 10" reflector rather than travel to the Orwell Park Observatory. However I subsequently discovered on the following Wednesday that several members had taken the opportunity of the clear Saturday night to use the Orwell Park Refractor for a search for the comet.

Although the comet would have risen about 10:00pm (BST), my eastern horizon is obscured by houses and it was about midnight before the region of sky containing Halley was visible from my observatory. At 00:05hrs (Sunday morning) I opened up the observatory and, using binoculars, began to familiarise myself with the area of sky containing the comet. Having found the correct area of sky with binoculars (there was no sign of the comet) I started to use the telescope. I first used my lowest power and widest field eyepiece, a 32mm Erfle. This gives a magnification of about 50x with almost a 1 degree field. I first identified the two stars 68 & 71 Orionis and then using the Sky and Telescope star chart as reproduced in last month's Journal I slowly 'star hopped' towards the predicted position of the comet. When I had the correct region of sky centred in the field I began searching for the comet. Although I could identify all the stars in the field on the star chart, there was no sign of the comet! I decided to increase magnification to darken the sky glow. Just before I changed eyepieces I glimpsed a very faint fuzzy patch but it was so elusive that I couldn't properly position it against the background stars. I then switched to a 20mm Erfle giving approximately 80x magnification. This darkened the sky significantly and at 1:15am on Sunday 13th October I had my first positive view of Halley's Comet.

It appeared as a very faint misty patch in the centre of which could be glimpsed (with averted vision) a small, almost stellar point. It was most reminiscent of the nucleus of a faint spiral galaxy. I increased the magnification to 200 times using a zoom Kellner eyepiece and then went to 280x with a 6mm orthoscopic eyepiece. With this magnification the stellar like nuclear region was clearly visible, the surrounding faint glow appeared circular 30-40 seconds of arc across. I decided at this time to go in and have a cup of coffee and then come out and draw the field. I left the telescope tracking the comet and came out again at about 2:00am. After about 15 minutes of dark adaptation I drew the field as shown below. However in the half hour or so that I had left the telescope a slight mist had come up and I had lost about half a magnitude of sensitivity. There were several other fainter stars not shown on the drawing or on the star chart that were clearly visible when I first sighted the comet. By the time I had finished recording the field the comet was becoming difficult to see (although I could still see all the stars shown on the Sky and Telescope chart. The comet was in fact considerably fainter than I expected it to be and I would estimate its magnitude as being around 12.5. The faintness was independently confirmed by the observers using the Orwell Park Refractor. They did not have a unanimously agreed visual sighting but did get a photograph of the region with a 15 minute exposure on HP5 film uprated to 3200 ASA. This negative has a faintly recorded object in precisely the same position as shown in the drawing (see accompanying article by A J Smith).

Halley's Comet,  M Barriskill

After an unsuccessful first attempt to observe this most famous of all comets on 27 August 1985, when it was probably too faint for my 8.5" reflector (the BAA magnitude prediction being 12.8), I have now made two successful visual observations, on 12 and 14 October.

On 12 October I used binoculars to locate the general area and then a wide field eyepiece in the reflector to find the exact position. At first there was no comet to be seen but after nearly 30 minutes of searching I started to suspect a very faint object in the predicted position. It could only be glimpsed with averted vision at first but with the sky transparency improving I became increasingly certain that it was Halley's Comet. I estimated the brightness at mag 11.5, a full magnitude fainter than most predictions, and the size at approximately 2 arc-minutes. It was generally diffuse but the nucleus was visible with high magnification. The naked eye limit by this time was mag 6.

The observation on 14 October was much the same as the previous one, with a delay before the comet became visible due to low altitude, but by 00:20 UT it was directly seen. Both the size and brightness were the same as on the 12 October.

Hopefully these will be only the first such observations of this long awaited and much heralded comet!

Once the comet had been located, further observations were obtained at Orwell Park Observatory and at members' home observatories. The following extracts from the OASI Newsletter provide details.

Some Observations Of Halley's Comet During November 1985,   D B Payne

My first observation of Halley's Comet in November was on Saturday 02 November. It was four days from full Moon but the bright gibbous moon was still causing significant interference and a slight haze did not help matters. However using the Sky and Telescope chart I quickly found the comet with my 25cm reflector about 0.25 degrees to the west of 109 Tauri /  Eta Tauri. I have a 75mm Maksutoy telescope attached to the 25cm reflector but there was no sign of the comet in this instrument. In the 25cm telescope the nucleus appeared more diffuse than in my first observation on 13 October also it was not central in the surrounding diffuse glow but offset to the north. This suggested that some tail might he forming but due to the acute angle subtended to the Earth and the faintness of the object it was not yet clearly visible.

I estimated the diameter of the diffuse region to he about 40 seconds of arc as seen in the 25cm reflector with an Erfle eyepiece giving 80x magnification.

On Sunday 03 November it was another clear night and the Moon was less of a disturbance although there was still a slight haze. Finding the comet was very easy this time using the 25cm reflector. At 11:30pm I was able to see the comet distinctly in the 75mm Maksutov and I attempted to find it with binoculars. At 11:40pm I could just make out a fuzzy patch using averted vision in 10x50 binoculars. This was my first binocular observation of the comet.

Monday was cloudy but Tuesday again afforded clear skies (despite it being bonfire night). The Moon had now waned and did not interfere and I found the comet without difficulty in 10x50 binoculars as a roundish misty patch. In binoculars however it displayed fairly uniform brightness without a defined nucleus region. I estimated it to be about 10 minutes of arc across.

Wednesday 06 and Thursday 07 November were both cloudy. Friday 08 November was also cloudy but with some clear breaks and I just managed to glimpse the comet with binoculars.

Saturday 09 November was also cloudy but on Sunday 10 November some reasonably clear skies permitted further observation. Again I easily found the comet with binoculars about 2 degrees east of the small arc of stars 72, 69, 65 and 67 Tauri. Using binoculars I estimated its diameter to be about 13 minutes of arc.

Monday l1 November was again clear but when I tried to find the comet with binoculars it apparently was not there! The seeing was fairly good and the sky was dark. The reason for the apparent lack of comet was its close proximity to the star 65 Tauri (mag 4.36) which was drowning it out! 

On Tuesday 12 November I again found the comet without difficulty with binoculars. By now the coma region could be seen against the surrounding glow and the shape had become triangular hinting at the beginnings of a tail.

Since Wednesday 13 November the bad weather has prevented any further observations.

An Observation Of Halley's Comet In December 1985,   D B Payne

December was generally a hopeless month for astronomical observations, at least from the Ipswich area! On the few nights that it was possible to observe the comet at Orwell Park Observatory we were inundated with visitors wishing to get a glimpse of the elusive object. Not wishing to turn the interested visitors away has meant that we have not been able to carry out a serious observational programme as intended.

Despite the generally awful weather during December, there was one night, Saturday 07 December, that had excellent seeing conditions. On that night I started observing the comet at 9.00pm with binoculars. The comet was easily visible about 0.5 degrees east of the pair of stars 31 and 32 Pisces. About 15 minutes later I could distinctly see the comet with the unaided eye - my one and only naked eye observation so far! In my ten inch reflector the comet was a glorious sight and for the first time I could make out significant structure. By this time I had half a dozen visitors all wishing to have the comet pointed out to them and a view of it through the telescope. This meant that I was unable to draw the comet until just after 10:00pm - unfortunately by this time the comet was beginning to sink down into a slight haze in the south west and I was unable to see the detail that I could see earlier.

The drawing below shows a rough sketch of what was still observable. The nucleus of the comet was almost stellar in the 10 inch using a 50x magnification Erfle eyepiece. Surrounding the nucleus was a bright coma fading to a fainter and core diffuse region that stretched to a tail at least 1.5 degrees long in the north east direction. In 'front' of the comet was an arc of material about 1 degree wide which appeared almost detached from the coma/tail region.

This was without doubt the best observation that I have had of Halley's Comet and could well be the best I will experience unless we get some excellent observing conditions in April. As an indication of the excellent seeing conditions of this evening, when observing the Orion Nebula (M42) I could see the two faint 11th magnitude stars in the trapezium clearly and steadily. Also for the first time ever I could distinctly glimpse the Merope nebula in the Pleiades!

Halley's Comet From Down Under,   A J Smith

On 03 April 1986, two members of OASI set off on what must be the most ambitious field trip yet undertaken by the Society. Roy Cheesman and I travelled through sub-zero temperatures and a blizzard to journey from Ipswich to Gatwick for a flight to the southern hemisphere to observe Halley's Comet. Thirty six hours after take-off from Gatwick we landed in record April temperatures at Sydney Airport to start an observing session that had been planned for two and a half years. By careful planning (?) we had managed to get a window seat on the Boeing 747 that would enable us to get our first glimpse of Halley's Comet at 12 km altitude just outside the airport of Abu Dhabi, the second of many stops (on what seemed to he a world tour!) en route to Australia.

After extricating ourselves from the clutches of Australian immigration officers (Roy seemed particularly attractive to close scrutiny) we boarded a coach for the short journey to our hotel. Here we would spend a night preparing to cross, overland, the whole continent from Sydney in the East, via Port Augusta in the South, to Darwin at the 'top'.

My first problem was to find a source of 24v power to enable me to charge (and recharge frequently) the power supply of the electrically driven equatorial mount that had caused so many headaches (and strange looks from customs officials). After some negotiations with the coach driver and some dismantling of various parts of the coach, a permanent switched supply was provided on the dashboard of the driver's pride and joy.

The first night provided us with a taste of things to come, and we eagerly scanned the magnificent southern skies between the clouds (the only clouds that we saw for three weeks!) The first day of the trip we spent touring Sydney Harbour by boat followed by the drive to Dubbo (a small town near Parkes Radio Observatory (the radio telescope used to chart the progress of the space probe Giotto a couple of weeks previously). The first day proved to be only the first of a succession of superlative sights, including the conducted tour of Parkes Observatory, the fantastic scenery of the Warnimbungle National Park, Siding Springs Anglo-Australian Telescope, Woomera Rocket Range, Coober Pedy opal mining town (where EVERYTHING happens underground, including the camping!) Ayers Rock, Henbury meteor craters, Alice Springs, Katherine Gorge and Darwin being only a selection of memories.

The southern skies can only he described as magnificent. We could see stars from horizon to horizon with easily recognisable constellations such as Orion appearing oddly, upside down and going backwards, being lost in the rich starfields of the Milky Way and Magellanic Clouds.

And what about Halley's Comet, I hear you ask. Well, similar to experience in the northern sky it was less than spectacular to the naked eye with only a five degree tail being visible. However, using telescopes and binoculars we could see the tail perform various complex manoeuvres from night to night.

We also witnessed other astronomical sights that were truly splendid, including most of the planets, the zodiacal light and a partial eclipse of the Sun. Our last view of Halley's Comet, to complete our tour of Australia, was probably the most bizarre from the perspective of the British psyche - from a swimming pool at 7 o'clock in the evening, with tropical palms waving overhead, night time temperatures of over 85 degrees Fahrenheit and a cool glass of something to enjoy!

We brought back nearly 1000 slides and memories that will last a lifetime, obviously too much to put into a short article for the Newsletter, so we will be holding a slide show and talk at the Friends Meeting House on 20 June where hopefully we will he able to share some of the sights of Australia and show some spectacular slides of the heavens.

The high public profile of Halley's Comet meant that many astronomical events were organised throughout the UK to coincide with its apparition. OASI opened the doors of Orwell Park Observatory on three occasions to enable the public to view Halley's Comet:

• Sunday 13 - Wednesday 16 November 1985

• Wed 11, Thu 12, Sat 14, Sun 15 December 1985

• Friday 25 - Saturday 26 April 1986

Unfortunately, the weather was not kind to the visitors and clear skies were rare on the open days!

J Appleton Original: Newsletters February, June, July, August, September, October, November, December 1985 and January, February, June 1986 Updated 11 September 2009