Archive for the ‘comet halley’ Category


Versatile spacecraft took on rendezvous job

November 30, 1985

Winnipeg Free Press, Saturday, November 30, 1985 page 63

FOR AMATEUR astronomers, this is a wonderful year for seeing comets. If it were not for Comet Halley, another comet would have been the most memorable astronomical object of the year. Comet Giacobini-Zinner was an easy object to see in a telescope, and it was the first comet ever to be visited by a spacecraft.

This August, as those of us in Manitoba were trying in vain to have our first glimpse of Comet Halley, the way to end a frustrating observing session was to look at Comet Giacobini-Zinner. It was an easy object in medium-size telescopes, it moved noticeably across the sky from night to night, and there was the knowledge that soon it was to be visited by a space probe.

Comet Giacobini-Zinner stays much closer to us, and the sun, than Comet Halley, and it returns every six and a half years. It has been observed 11 times since it was discovered by Michel Giacobini in 1900. At its closest point to the sun, it is just slightly beyond the orbit of the earth. This is ideal for an approach by a space vehicle.

Fleet of spacecraft

Although there is a small fleet of space craft heading for Comet Halley, none is from the United States. For those interested in the U.S. space program, this is a major disappointment. On Sept. 11, the U.S. probe ICE penetrated the head of comet Giacobini-Zinner, and beat all the other missions to a comet.

ICE began its existence as International Sun-Earth Explorer 3 (ISEE-3), a little spacecraft that was designed to park itself in orbit around the earth, at an altitude of 120 times the diameter of the earth, in the direction of the sun. (The moon is only 30 earth diameters away.) It was supposed to quietly monitor the solar wind; its designers never thought about comets.

Fortunately, to stay in orbit, it required the use of onboard maneuvering thruster rockets. After three years ISEE-3 proved it was a versatile craft when it carried out a second mission. Using the thrusters, it journeyed to the other side of the earth to investigate activity in the other regions of the earth’s magnetic field. That was in 1982, and U.S. space planners had heard the final word that they would not have the budget for the Comet Halley mission. Now they had an alternate plan.

For the low cost of three million U.S. dollars, ISEE-3 became International Comet Explorer (ICE) and, on Feb. 8, 1983, It was on its way to rendezvous with Comet Giacobini-Zinner.

Success story

While It is a wonderful success story, those of us who work at a planetarium tend not to be as enthusiastic about ICE as the mission merits. Since it is designed to measure the activity of the solar wind, it contained no cameras. We have trouble showing people who visit the planetarium a lot of data — we prefer to show pictures. ICE is blind. Instead, ICE can measure magnetic fields, detect sub-atomic particles, and record the energy of radio waves. This instrumentation was well suited for a mission to a comet, and it produced some new information about comets, and the changes in space caused by their passage.

ICE roared into the tail of the comet at the meteor-like speed of 21 kilometres per second. Although the comet looked like a tiny wisp of light in our telescopes, and in spite of the fact that the lump of ice at the centre of the comet — the nucleus is only a kilometre in diameter, the atmosphere around the comet is vast. ICE spent two hours and 42 minutes traversing 204,000 kilometres of the interior of the comet. Scarcely a second passed when a particle of dust did not strike the antenna. There was some concern that, if any larger particles were encountered, the craft might be disabled.

Scientists are gloating over the fact that most of the new information confirms the current theories about how comets behave. They discovered that the most common molecule sublimating from the comet’s nucleus is water. This is consistent with our picture of a comet; that is, 85 per cent frozen water with ices of carbon monoxide, methane and ammonia, along with fine dust and perhaps some rocks.

Some of the surprises include the discovery that the interior of the comet’s tail is writhing with magnetic fields. It was thought that the interaction between the magnetic field of the comet and the solar wind would be similar to that which occurs around the earth and other planets. Here, the solar wind compresses the magnetic field of the earth, which can then effectively deflect much of the wind. ICE produced evidence of more complex processes.

Soon, the European Space Agencies’ space craft, Giotto, will plunge into the head of Comet Halley. It will fly so close to the nucleus of the comet that it will be destroyed by the density of material streaming away from the comet. It has a huge battery of scientific equipment on board, including a camera. Pictures!

With all of Giotto’s discoveries, it will be hard to remember this little craft that was the first to fly by a comet.

Valuable service

The ICE mission to Comet Giacobini-Zinner performed a very valuable service. In addition to providing information about the environment of the comet that will be useful in determining the best trajectory for Giotto, it gives us two comet examples to study. Although the U.S. did not manage a mission to Comet Halley, their clever use of ICE will contribute to our understanding of Halley, and all comets.


While posting this article to the blog, The Return of Comet Halley, I came across this account of the recent contacts with the spacecraft ICE called “IT’S ALIVE!” << Follow the link to read that article posted at The Planetary Society. If ICE is to have another comet mission after it returns to the Earth-Moon in 2014, the person who will likely make the proposal is Jim Slavin.

In 1985 Robert Ballantyne was director of the Manitoba Planetarium. His weekly column in the Winnipeg Free Press, called Sky Watch, focused on the return of Comet Halley.

© 1985 Robert Ballantyne and The Winnipeg Free Press

Added to this blog on 2010 April 18

Sky Watch - Robert Ballantyne | Winnipeg Free Press


Big crowd disrupts schedule

November 23, 1985

Thousands see Halley, get a look at Jupiter

THE HEATER IN THE VAN DIDN’T work very well, and we thought that was an advantage for the big telescope in the back. Telescopes need to be the same temperature as the surrounding air to avoid air currents in the tube and the resulting degradation of the image. The cool air was relief. Bill Peters and I were over-dressed in anticipation of standing for hours in the cold. The newly-emerged stars were motionless above the speeding countryside. We were heading for Steinbach.

One sure way to guarantee a blizzard is to plan a public observing night. We were rejoicing: the sky was cloudless, and the temperature was unseasonably warm. Bill looked at the thin crescent moon about to set in the west. “That moon is like an advertisement,” he said, “lots of people will see it and think of Comet Halley Sky Watch No. 1. We could have a good turn out.”

It was Nov. 15, and we had announced that this would be the first chance for people to see Comet Halley. We wanted to be out of Winnipeg to avoid the light pollution, but l wondered how many people would drive to see a little fuzzy object in a telescope.

Excellent facilities

We thought we were well prepared. The Mennonite Village Museum was providing excellent facilities, including a heated restaurant and lecture room, and an adjacent lot with electricity for the telescopes. The Royal Astronomical Society of Canada, Winnipeg Centre, and the Manitoba Astronomical Club were bringing a total of 14 telescopes. There would be a series of indoor lectures, and two television crews: Switchback and CBC 24 Hours Late Night News. All we needed was a few people to show up.

We arrived at 6:30 p.m., an hour before the public was invited. There already were a few dozen cars, and a fair crowd of people. Peter Goertzen, director of the Museum, said they had started to arrive at 5 p.m.

I began to wonder if we really were prepared. During the next hour the flow of cars arriving increased from about one a minute, to bumper-to-bumper. The large yard for telescopes was as crowded as cocktail party, and half of the telescopes hadn’t arrived. Many members of the committee were still in their cars, trying to drive into the site. The TV crews were showing up and some of the kids had discovered that Laurie Mustard was here! Now I was sure. We were not prepared for the crowds.

Winnipeg Free Press 1985nov23 Planetarium Sky Watch number 1

Comet watchers lined up at the Steinbach Mennonite Village Museum for a look through a telescope

The next hour-and-a-half was a blur of setting up telescopes, working with TV crews, giving astronomical talks to groups, and telling countless people where the comet was in the sky (at that time it was near the Pleiades), and that it was just possible to see it with 7 x 50 binoculars, but probably not in 7 x 30s. Some people wisely had brought their binoculars so they could learn how to find the comet, and then be able to follow it by themselves in the weeks to come. I remember everyone as being very friendly, patient, and in remarkably good spirits as we tried to get our act together. Someone estimated there were more than 2,000 visitors.

Although it looked like a clear evening, there were some ice crystals at low altitude and it made the comet, which was low in the east, hard to spot, even in the bigger telescopes.

Some time after 9 p.m., things calmed down. The telescopes had arrived, were set up, and cooled to air temperature. Comet Halley was high enough to be seen in even the smallest telescopes, and the lines of people were moving in an orderly fashion. It was hard to believe. Our carefully worked out schedule of who was supposed to be at what post was in a shambles, but it didn’t really matter. The evening was mild enough that the telescope operators agreed to stay outside for more than the planned 1/2 hour shifts.

“Look down into this plumbing,” I said for the, umpteenth time, referring to the eyepiece that was at right angles to the telescope, “and move your head until you see the stars. The comet is right in the centre of the field. It looks as if someone has erased some of the black of the sky.” Often, to make sure that people were actually seeing Comet Halley, I would ask them to describe what they saw. “A piece of lint” said Laurie Mustard.

Early in the evening, some of the telescopes were focused on the planet Jupiter, until it settled into the trees. Towards 11 p.m. people had a chance to see the Andromeda Galaxy, and the greenish fan-shaped Great Orion Nebula. By that time the sky was clear, the lines relatively short, and many folks looked at the comet several times through a variety of telescopes. One of the plans that had not materialized was to count the number of people who attended. Judging by the length of lines at telescopes, and the number of cars that had arrived, we estimated we had shown Comet Halley to about 4,000 people.

The comet was not impressive, but this was only the first look. Between now and January it will move rapidly from the eastern sky to the western sky at sunset. During this time, it will grow from a small, dim, hazy patch of light, to the traditional image of a comet — complete with a tail. If it continues to develop as we have predicted, by Jan. 10, everyone should he able to see it without the benefit of a telescope. It is my hope that some of the people who saw it at this early stage will be able to feel that they have personal sense of this astronomical object, hurtling through space and being transformed by its encounter with the sun.

Next viewing

On Monday I had a call from someone who wanted to know when Comet Halley Sky Watch No. 2 would be held. We are planning several programs including something for mid-December and at least one in January. Comet Halley Sky Watch No. 2 will be a more modest event at the Fort Whyte Centre for Environmental Education Dec. 8. The space for this one is limited and there is a charge. For information call, the Fort Whyte Centre

In 1985 Robert Ballantyne was director of the Manitoba Planetarium. His weekly column in the Winnipeg Free Press, called Sky Watch, focused on the return of Comet Halley.

© 1985 Robert Ballantyne and The Winnipeg Free Press

Sky Watch - Robert Ballantyne | Winnipeg Free Press


Star-gazers plan Halley night

November 9, 1985

COMET HALLEY IS IN THE sky. It is moving noticeably among the stars from night to night. Since we first saw it in August, local observers have watched it become transformed from something so faint that it was barely perceptible in the biggest telescopes, to a hazy ball of light that is visible in a midsized amateur telescope. One especially sharp-eyed person reports that she could easily see the beginnings of a tail on the comet.

If you do not have a telescope, you will have your first chance to see Comet Halley next Friday night.

Comet Halley Sky Watch #1 will take place at the Mennonite Village Museum, just north of Steinbach, between the hours of 7:30 p.m. and 11 p.m. Admission is free.

Very often, when the public is invited to look through telescopes, they do not have the opportunity to learn exactly what it is that they are seeing. The wonder of the telescope is not that it shows beautiful views of the universe — often the objects seen are faint and indistinct, and certainly not self-explanatory — but that you can see real things that populate our galaxy. When we can understand what it is that we are seeing, we can begin to develop a sense of who we are, and how and where we fit into this universe. For this reason, Comet Halley Sky Watch #1 will have an indoor program to explain something about the telescopes, to give some background on Comet Halley, and to talk about some of the other interesting things in the sky. Because of the indoor program, Comet Halley Sky Watch #1 will take place even if there is a cloudy sky.

Several organizations are combining forces to give us this early look at Comet Halley: the Manitoba Planetarium of the Manitoba Museum of Man & Nature, the Royal Astronomical Society of Canada (RASC) — Winnipeg Centre, The Manitoba Astronomy Club (MAC), and the Mennonite Village Museum. Each is providing volunteers to make the event happen. For a long time we have known that Nov. 15 would be a special observing night for the comet. As you may know from reading these articles, the best time to view a faint object, like the comet, is when the moon is not around. Therefore we seem to have a series of good observations once a month during the dark of the moon, and then we have to wait while the moon goes by; and the next month we are back out to see what has happened.

Moon waning

This past week the moon had been waning away in the early morning sky. On Tuesday there is a new moon, which means that the moon is so close to the sun in the sky that you will not see it. For the next two weeks, the comet observers will be out with their telescopes.

Incidentally, and this has nothing to do with the comet, at the time of the new moon, there will be a total eclipse of the sun. If you want to see it, the best place for viewing will be north of the Ross Sea on the coast of Antarctica. I know that it will be spectacular, and I wish I could be there.

The other thing that makes next Friday special is that it is the first of three days during which Comet Halley will be sliding past a very prominent star cluster called The Seven Sisters or The Pleiades. This means it will be very easy for everyone to look up in the sky and know exactly where the telescopes are pointing.

In addition to observing the comet, Comet Halley Sky Watch #1 will have telescopes trained on a number of interesting astronomical objects. The Pleiades look stunning in small rich-field telescopes. It is a galactic star cluster, a group of stars which are all young and hot. They were born together from the same dust cloud and they are continuing to move together through space. There are several beautiful clusters in this part of the sky.

This is the best time of year to observe the Great Galaxy in the constellation of Andromeda. This vast whirlpool of stars is the giant in the local group of galaxies, and If you have good eyesight, it is the most distant thing you can see without a telescope. It is one of those objects that does not look impressive, but when you understand what you are seeing, it is awesome.

Jupiter is the brightest star-like object shining in the southwestern sky lately. Because of its churning atmosphere and its family of moons, it’s always an interesting sight in a telescope.

Astronomy buffs

Free Press caption: Powerful scope is essential for astronomer Ballantyne

Powerful scope is essential for astronomer Ballantyne

If you have ever thought you might be interested in astronomy as a hobby, or if you have been considering buying a telescope, Comet Halley Sky Watch #1 will, give you the chance to meet people who love the subject and have considerable experience. Both the Royal Astronomical Society and the Manitoba Astronomy Club will have tables set up to explain what they are all about. The RASC accepts membership from anyone with an interest in astronomy over the age of 16. MAC is associated with the Planetarium and its members are all under 18. In addition to looking through the telescopes, be sure to ask the operators about the size and nature of their ‘scopes, and then compare with the others. Consider cost and convenience as well as the optical excellence of each.

Folks in Thompson can see the comet Friday Nov. 15 if the sky is clear. Bill Taylor will have a program at Eastwood School, with a movie at 7 p.m., followed by viewing of the comet through an eight-inch (20.32-centimetre) telescope. If the weather is cloudy, the viewing may be rescheduled

In 1985 Robert Ballantyne was director of the Manitoba Planetarium. His weekly column in the Winnipeg Free Press, called Sky Watch, focused on the return of Comet Halley.

© 1985 Robert Ballantyne and The Winnipeg Free Press

Sky Watch - Robert Ballantyne | Winnipeg Free Press


Comet gives closer look at 1910 photos

November 2, 1985

Study of old photos will help chart way through the comet’s maelstrom

GOOD OBSERVATIONS, and good records have always proved useful in astrononmy. Over the years it is amazing how often a new theory insight has been helped by examining existing observations.

When a faint Saturn-like ring around the planet Jupiter was discovered by the Voyager spacecraft, everyone was amazed; except for S.K. Vsekhsuyatskij who, two decades before, had published observations of the shadows of the rings cast on the surface of Jupiter. Unfortunately, at the time, this significant discovery went almost unnoticed.

Now the photographs of Comet Halley taken in 1910, the last time the comet was in our skies, are being reworked to find detail that the original observers never dreamed was there. The difference is that the astronomers of 1910 did not have the benefit of computers, so they had no way of seeing all of the information in the pictures they were taking.

Great astronomer

One of the great astronomers of the early part of the century was George Ritchey of Mount Wilson Observatory in California. Among his many achievements, he was responsible for grinding the mirror of the 100-inch telescope — at the time the largest in the world.

It was through this mighty eye that our universe was transformed from a single galaxy, our Milky Way, to a cosmos populated with countless galaxies.

Comet Halley 1910 Ritchey / Larson

Top Photos taken June 2 (left) and June 5, 1910. With computer enhancements below.

Photographs of Comet Halley, taken by George Ritchey in 1910, were the result of the same kind of painstaking labor known to any astronomer today.

A telescope and a camera are technically the same thing. When it is a telescope, an eyepiece is placed at the viewing end, and the astronomer can look at the image created by the telescope.

When it is a camera, a film plate is placed at the locus the telescope. The advantage of film is that it can soak-up light over a long period of time and reveal more than the eye can see. It is the astronomer’s job to make sure that the telescope never wavers from the object during the exposure. An astronomical exposure may take from a few minutes to several hours.

The process of controlling the telescope during photography is called ‘guiding’. This is necessary because the sky is always moving due to the rotation of the earth.

Telescopes have clockwork motor systems to drive the telescope across the sky at the same rate as the stars. Because of the slight magnifications, small adjustments are always required. The astronomer borrows some of the light coming through the telescope for an eyepiece. This eyepiece has a dimly illuminated pair of cross-hairs. The object photographed, or a nearby star is placed in the cross-hairs, and the astronomer keeps it there by speeding up or slowing the telescope

It is a tedious and exact job, and there is no room for error.

Comets are more difficult to photograph than most objects In the sky because they move independently of the stars.

This fall, when Bill Peters was in Arizona researching material for the planetarium show The Comet Adventure, he obtained a remarkable series of photographs from astronomer Stephen M. Larson.

Precisely guided

As part Of their preparation for the new pictures that will be taken of Comet Halley, Larson and his colleagues used 1910 photographs, and a computer to see if they could find new ways to process photographic data. Fortunately, those pictures were taken by George Ritchey. His guiding was so precise that the pictures preserved detail that he never saw.

Look closely at the accompanying pairs of pictures. They are the head, or coma, of Comet Halley as taken by Ritchey on the nights of June 2 and June 5, 1910. The top version are the images as Ritchey saw them, just hazy balls of light. Below each is the computer enhancement. There is much more detail.

In each picture there are a number of wavy streaks. These are stars. During the exposure the telescope was following the comet, which was moving compared to the stars. Each of the little ripples in the star-trails is a correction that Ritchey made at the telescope.

Many more stars

The computer pictures show many more stars. They also have some spurious shadow images of the stars that can sometimes be seen as black lines.

The really interesting features are the jets, and shells of comet material. The picture taken June 2 shows a jet appearing from the bottom of the nucleus, the next day the stream is much longer, and fainter. If the jet is not as violent, it forms a spiral as the comet rotates.

The energy for this material being ejected from the surface of the comet is the heat from the sun. We are seeing the comet-version of a volcano. The gases in the jets are accelerated to speeds of one to two kilometers per second. The sun-warmed surface of a comet must be a dynamic and exciting place.

Both the European Space Agency spacecraft, Giotto, and the Soviet probes, Vega 1 and Vega 2, will fly into the head of the comet, and try to get close to the nucleus. These jets could be fatal to the delicate craft. Larson will be analyzing, and he will recommend the safest route through the danger zone.

In 1985 Robert Ballantyne was director of the Manitoba Planetarium. His weekly column in the Winnipeg Free Press, called Sky Watch, focused on the return of Comet Halley.

© 1985 Robert Ballantyne and The Winnipeg Free Press

Sky Watch - Robert Ballantyne | Winnipeg Free Press


New discoveries help Planetarium design comet model

October 26, 1985

ASTRONOMERS LOVE TO DESCRIBE nature in terms of numbers and mathematical formulae. At the planetarium, we look at all of this and say, “Yes, that is all very interesting, but what does it look like?” A planetarium has to be able to show it. The question is simple, but it can produce some interesting results.

Because it is small and well concealed inside the atmosphere, or coma, of the comet, the nucleus of Comet Halley has been the invisible author of the great celestial show that we see every 75 years.

When it returns

In the new planetarium program, The Comet Adventure, producer Bill Peters wanted the show to illustrate what it might be like as the first humans land on the icy heart of Comet Halley, when it next returns in the year 2061. Artist Ed Barker had to find the answer to “what does it look like?” Everyone imagined that, because the comet is icy, the surface of the comet would present a miniature Arctic scene.

The first clue that this concept might be misleading came from some of the new research that was done on Comet Halley early this year. Astronomers made a series of infrared measurements with the three-meter NASA infrared telescope facility, and the 2.2-meter University of Hawaii telescope on Mauna Kea, in Hawaii. Surprisingly, they were able to announce the approximate color of the comet’s nucleus.

At the beginning of 1985, the comet was close enough to the sun that its heat was starting to evaporate some of the surface ices to produce the coma. There was a short period between the time when the nucleus was close enough, and bright enough to observe, and the point when the nucleus vanished inside the growing coma.

The astronomers measured light from the nucleus through filters at different wave-lengths, and were able to deduce that they were looking at a very dark reddish object. The astronomers said “No comet observed by us has a color consistent with clean ice.” This was exciting new information.

For dramatic reasons, we wanted the surface of the comet to be an active place. The next piece of startling evidence was collected during the 1910 passage of Comet Halley, although the researchers at the time did not know what they had found.


In Arizona, planetary astronomer Stephen Larson has been re-working 1910 photographs of Halley using a computer to enhance some of the features. As a result, Larson has been able to derive the speed of rotation of the Comet, as well as the orientation of its spin axis.

For our show, we discovered the surface of comets could be very dynamic. Warmed by the sun, the gases do not simply evaporate from the surface of the comet like snow on a sunny day. Larson’s pictures show violent jets of material being spewed into space.

Bill Peters and Ed Barker work on planetarium comet model special FX

Recent discoveries aid Planetarium staff in making comet model

Barker decided to illustrate the changes that take place on the surface on the comet by building a model of the surface. We use full-circle photography of the model to put the audience right in the scene.

He began with Styrofoam on a doughnut-shaped table that was 5-1/2 feet in diameter. It had a two-foot hole in the centre for the camera. For days Baker worked with a hot-wire Styrofoam knife to sculpt the fantastic surface of the comet as it was when it was as far from the sun as planet Jupiter. This is the point when the sun is just beginning to transform the sleeping comet from the little ice world that has remained unchanged since it headed out of the solar system in 1986, to the fuming giant that will shine in earthly skies In 2061.

Acrid smell

When the acrid smell of burning plastic faded, Barker was spraying, dabbing, and brushing the surface with a palette of colors, especially reds. Carborundum and barnsite (grit) were worked into the surface for texture. And finally, he added a dusting of stucco sparkle to provide reflections from the comet’s crystals.

The Fred Whipple, a comet-lander spacecraft, was added to the scene and photographed. Immediately, Barker attacked the surface of the comet with the hot-wire knife, lopping off icy spires, and opening up fissures where special-effects projectors will allow great jets of gasses to vent into space. This is the comet at its closest approach to the sun. Four scenes use this model. When we last see it, there is a light frosting of ice crystals caused by some of the coma freezing to the surface of the comet as it begins another 75 year Journey away from the sun.

At the planetarium, we will be interested in all of the new information that will be discovered about Comet Halley in the coming year. We particularly will be intrigued to see if there is anything that will indicate how accurate we are with our images of the comet’s nucleus.

In 1985 Robert Ballantyne was director of the Manitoba Planetarium. His weekly column in the Winnipeg Free Press, called Sky Watch, focused on the return of Comet Halley.

© 1985 Robert Ballantyne and The Winnipeg Free Press

Sky Watch - Robert Ballantyne | Winnipeg Free Press