Once (or twice) in a lifetime

During the 18th century the appearance of Halley's Comet was a once-in-a-lifetime experience. Today many live to see it twice, while numerous stamps depict the comet for those who miss it.

Naming the comet

Since Halley lived from 1656 to 1742, it is interesting to learn why an object that had been seen for so long should have become known by his name. The reason was that, until Halley performed the calculations, nobody had realised the comets which kept appearing were, in fact, the same one returning on a regular orbit. Edmond Halley was able to forecast the comet's appearances thanks, in part, to the work of Sir Isaac Newton, who had recently completed studies on the effects of gravity.

Only once for Halley...

Halley first saw the comet that would take his name in 1682. Using the formula he had developed, he forecast it would not be seen again for another 76 years. His prediction was accurate and the comet was sighted again in England on Christmas Day 1758, making this year the 250th anniversary. Unfortunately, Halley's sighting proved to be a once-in-a-lifetime experience, as he died 16 years earlier.

...but twice for Mark Twain

At the time, the period between sightings was far greater than the average life expectancy in Britain. Thus, the phrase that seeing Halley’s comet was a ‘once-in-a-lifetime’ event has been absorbed into the English language to mean any rare happening. The famous American author, Mark Twain, is noted for having been born in 1835, a year in which Halley’s comet was visible. Curiously, he died in 1910, which was also the year of the comet’s return. Thus, despite the saying, his own life spanned the exact time of one complete orbit of Halley’s comet.

A change of phrase?

Now that life expectancy has improved, this phrase requires a slight amendment to read ‘once-or-maybe-twice-in-a-lifetime’. This explains the use of the word ‘maybe’ on the 31p British stamp issued in 1986 to commemorate the comet's appearance that year. The artist Ralph Steadman drew the four stamps issued by Royal Mail for this event and received a BBC Design Award for the set.

More stamps for the 1986 sighting...

The appearance of the comet in 1986 was accompanied by a very large number of stamps. The design shown here from Guyana demonstrated the period between sightings using stamps. Issued se-tenant, the left hand stamp bore a reproduction of a 1910 stamp, whilst the other half portrayed a stamp that had appeared in 1986. These were the two dates when the comet was last visible from Earth. The drawing of the comet is shown above the two stamp impressions. Brazil’s commemorative stamp in the same year simply showed the comet in flight.

...but not all feature the astronomer

Many of the countries had issues containing multiple values, and, on at least one of these, a portrait of Halley was included. Examples are shown here from Sri Lanka and St Vincent. The first day cover from Poland issued for the same occasion showed a different portrait. It was of Professor Michal Kamienski, the director of the Warsaw University Astronomical Observatory, who was recognised as the world’s leading expert on the orbits of comets.

Honouring Halley

The 1986 issues to mark the appearance of Halley’s comet came from the following countries: Anguilla; Antigua; Barbuda; Belize; Benin; Bhutan; British Antarctic Territory; Central African Republic; Christmas Island; Comoro Islands; Congo Republic; Cyprus; Dominica; Grenada; Guinea; Hong Kong; Hungary; Ivory Coast; Laos; Maldives; Mauritania; Mauritius; Mexico; Montserrat; Romania; Russia; St. Helena; Samoa; Seychelles; Togo; Tonga; Uganda; Vanuatu; and Zambia. There have been stamps featuring Halley in other years and these are usually part of larger sets honouring famous scientists.