© 1985, Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, CA 94112
Editor's Note: We have now entered what comet expert John Brandt of NASA has called "the golden year of comet exploration.'' The International Cometary Explorer (ICE) spacecraft has now had a close encounter of the best kind (the real kind) with Comet Giacobini-Zinner and has returned a host of useful scientific information. Telescopes on Earth (and aboard several spacecraft) will be turning more and more frequently toward the faint fuzzy patch in the sky which is Halley's Comet, approaching us from the realm of the outer planets.
This issue is devoted to the coming of the comet and to how you can prepare yourself and your students for finding, observing, and — most importantly — understanding the most famous of all celestial visitors. In this year of incredible "Halley hype,'' teachers will have an even greater responsibility than usual to help the students bring the real science and exploration into focus. The astronomers who work on this newsletter very much hope we can be of some small assistance to you in this important task.
Comets Events Schedule: 1985-86
[During March of 1986, five spacecraft will fly by the comet and study the nucleus (the dirty snowball, just a few miles across which is the main body of the comet), the coma (the much larger cloud of evaporated gas and dust, formed by the Sun's radiation), and the tail (the long streamers of comet material pushed away from the nucleus by the Sun's radiation and wind). Several of the spacecraft are equipped with excellent cameras that will send back historic first photographs of what a comet looks like close-up, as well as a steady stream of other scientific data.
Note: All the spacecraft encounter dates below are tentative and subject to minor revision.]
|The European Space Agency's Giotto spacecraft (above) will, if all goes well, come within 500 km of Comet Halley's nucleus on March 14,1986.|
|Where to look for Halley's Comet|
|This diagram shows where Halleys Comet will appear in the sky as seen from mid-northern latitudes. For January and late April, the comet is shown where it will be at sunset; for late March to early April, it is shown at sunrise. The tail is shown pointing in the proper directions, but its length is an estimate only (for clear, moonless, and very dark skies away from city lights.) (Chart adapted from one in The Comet Halley Handbook by D.K. Yeomans.)|
Best Times to See Halley's Comet (from the Northern Hemisphere)As many of you may have heard by now, this will be the worst pass of Halley's Comet in 2000 years as far as viewing the comet is concerned. (Just our luck!) From most urban areas, the faintness of the comet in the sky and the brightness of city lights will conspire to make the comet impossible to see with the naked eye. Also the comet will be low on the horizon from most of the U.S., so you will need to find a location with a clear view of the horizon (not generally an easy task, since even low buildings and trees may get in the way.) See the accompanying Halley observing chart.
Our suggestion is that families should try to find a good dark, country location to view the comet on a weekend camping trip, for example. The best instrument will usually be a pair of binoculars, since most typical telescopes restrict your held of view too much to be useful for comet viewing.
|Path of Halley's Comet Between November 1985 and May 1986|
This chart shows the path of Comet Halley through the constellations from November 1985 through May 1986. We should note that current estimates are that the comet may not be visible to the unaided eye in most areas before January or after April. Also, during February the comet will be behind the Sun and thus not visible from Earth.
Declination, the north-south coordinate, is expressed in degrees north ( + ) or south ( - ) of the celestial equator. Right Ascension, the east-west coordinate, is expressed in hours (24 hours all the way around) eastward from the point in Pisces where the Sun crosses the celestial equator at the spring equinox.
(Chart adapted from one in The Comet Halley Handbook by D.K. Yeomans.)
| 1 | 2 | next page >>
back to Teachers' Newsletter Main Page