Halley’s Comet: The 1758 Return Halley Foretold, Never Saw

What did Halley print in 1705?

Halley had worked out orbits for every comet with good enough observations and set them out in one table (Exhibit A, pp. 6–7). Three of them looked alike. He wrote that there were “many Things which make me believe” that the comet Peter Apian watched in 1531 was the one Kepler and Longomontanus described in 1607, “and which I my self have seen return” in 1682 (Exhibit A, p. 21).

The comet Halley saw in 1682, as drawn by Johannes Hevelius, reproduced in Chambers, The Story of the Comets (1909), p. 105. Chambers dates the drawing January 9, 1683, in his caption, but his text says the ray was seen from about September 8, 1682.

The gaps between those sightings were not equal. Halley addressed that head on. The inequality, he wrote, “is not so great neither, as that it may not be owing to Physical Causes,” and he compared the pull that Jupiter puts on Saturn. He added a fourth sighting, a comet of summer 1456, and then came to the sentence that made the comet his: “Hence I dare venture to foretell, That it will return again in the Year 1758” (Exhibit A, p. 22).

The 1705 printing matters because it was public long before the test. A dated book shows that the forecast existed by that date at the latest, the kind of evidence explained on how a printed date sets the latest possible date. The dated printing also separates it from a famous line that cannot be traced to the man it is pinned on, the case retried on the 1899 patent-office quotation.

How was the forecast split and scored?

The paragraph on pages 21 and 22 makes five claims that can be checked one at a time. The list below was fixed before any claim was graded; the downloadable table uses the same list. One more sentence was left out: Halley floated the idea that the comets of 1532 and 1661 might be one, then set it aside in the same paragraph because Apian’s observations were “too rude and unskilful, for any thing of Certainty.”

1. The comets of 1531, 1607 and 1682 were one comet.
2. The unequal gaps between them could come from physical causes.
3. The comet of 1456 was the same one.
4. It would return in the year 1758.
5. If it did, Halley wrote, “we shall have no Reason to doubt” that the other comets return too.

Only item 4 carries a deadline in Halley’s words: the end of 1758. For items 1 to 3 this site reads the deadline as the 1758–1759 return and the orbit work published by 1910. Item 5 has no deadline at all: Halley left the other comets to astronomers “for many Ages” (Exhibit A, p. 22). The same rules score the 1900 Ladies’ Home Journal forecast and Albert Robida’s picture of 1955.

Halley’s 1705 forecast, item by item, with the grade for each. Drawn from the forecast table published with this page; claims from Halley (Exhibit A), graded under this site’s rules against the evidence in Chambers (Exhibit C) and the 1911 Britannica (Exhibit D).

The five claims, with grades, reasons and sources (CSV) (where the data comes from) Data: Edmund Halley, A Synopsis of the Astronomy of Comets (1705); George F. Chambers, The Story of the Comets (1909); Encyclopaedia Britannica, 11th ed., vol. 6 (1910), "Comet"

By the strict count, 3 of the 4 scorable claims are hits, or 75%. By the lenient count, which adds the partial hit, 4 of 4 hold up. Item 5 is left out of both counts.

When did the comet come back?

The test for item 4 was set before grading: if both the first sighting and the perihelion fell in 1758, the claim is a hit; if one did, it is partial. Perihelion is the point where a comet passes closest to the Sun, and astronomers time its returns by it. The comet met one condition, not both.

Astronomers in Paris had worked the problem first. On November 14, 1758, Alexis Clairaut told the Academy of Sciences that Jupiter would hold the comet back 518 days and Saturn another 100, and he gave April 13, 1759, for the perihelion, allowing a month either way (Exhibit C, pp. 108–109). Clairaut’s paper is known here only through Chambers.

Illustration

Illustration of a winter night in 1758: a farmyard watcher searching the sky with a telescope. Not a record of the first known sighting.

In Chambers’s account, the first person to find it was not a professional. He names Palitzsch, a farmer at Prohlis near Dresden who studied astronomy, and says he “saw it on the night of Christmas Day, 1758,” with a telescope of eight feet focus (Exhibit C, p. 109). Charles Messier in Paris caught it on January 21, 1759. The comet passed perihelion on March 12, 1759, which Chambers calls “just within the limits assigned by Clairaut” (Exhibit C, p. 110), though the gap from Clairaut’s date is 32 days, one day more than a calendar month.

So the comet was back in sight within the year Halley named, with six days to spare, and it reached perihelion on March 12, 1759, 77 days after the first sighting. That split is why item 4 is graded partial, not hit.

Did Halley change the date before he died?

He did, in his later tables. Halley’s astronomical tables came out in 1749, after his death, and an English abridgement printed in London in 1757 reports what they said (Exhibit B). There he recalls that in 1705 he had told readers to watch for the return, “which I expected about the year 1758” (p. 15).

Edmund Halley in an engraved portrait inscribed with his titles, reproduced as plate XIa in Chambers, The Story of the Comets (1909).

The later text is more careful about the date. It says the pull of the planets might stretch the next period past 76 years, so the comet “may not be seen again till the end of the year 1758, or beginning of 1759” (Exhibit B, p. 18). That wording fits the event better than the 1705 sentence does, but this page scores the 1705 text, which was the one in print first.

The later tables were written in Latin, and Chambers gives Halley’s line in English: if the comet came back “according to our prediction about the year 1758,” then “impartial posterity will not refuse to acknowledge that this was first discovered by an Englishman” (Exhibit C, p. 106). The 1757 abridgement puts the same claim in reported speech (Exhibit B, p. 20). Nothing in either text speaks of a hope or fear about the world beyond credit for the discovery. For the time-stamped wish, Halley is a counterexample: his forecast is a sum worked from orbits, with little in it to read about his own era’s wishes.

What did the 1835 and 1910 returns add?

Each return after 1759 retested the period, and each came on a schedule set in advance. In 1835 the comet was first seen on August 6 at the Collegio Romano in Rome, and the perihelion fell on November 15, 1835 (Exhibit C, pp. 112–113). Chambers gives November 16 on the page before; the 1911 Britannica table gives November 15 (Exhibit D).

Halley’s Comet in 1835–36, drawn by C. P. Smyth: the long tail on November 11, 1835, then the head without a tail on seven nights in January and February 1836. Plate I in George F. Chambers, The Story of the Comets (1909).

For 1910, the 1911 Britannica records that Max Wolf at Heidelberg detected the comet on photographic plates exposed on September 11, 1909, and that it was then found on a Greenwich plate of September 9 (Exhibit D). Chambers, writing in 1909, expected the perihelion “about the middle of April” 1910 (Exhibit C, pp. 123–124). Over all seven returns in the table, the gaps run from 75 to 77 years.

Was there a panic in 1910?

What can be shown is that the danger was raised in print before the comet arrived. In a passage of Comet Lore (1910) written before the date, Edwin Emerson wrote that the Earth would pass through the comet’s tail on May 18, 1910 (Exhibit E). He reported that the spectroscope had found cyanogen, a poisonous compound, in the tail, and he admitted that no one could say for certain what would happen.

Halley’s Comet on May 4, 1910, photographed by E. E. Barnard at Yerkes Observatory and printed in the 1911 Encyclopaedia Britannica, vol. 6, plate II (Exhibit D).

Whether ordinary readers panicked is a separate question, and it needs the newspapers of May 1910. This page could not read them, so the stories of a public scare and of comet pills are not scored here and are not repeated as fact. Ronald Stoyan’s Atlas of Great Comets (2015) has a chapter on the 1910 return as a whole, cited here from its bibliographic entry only (Exhibit F).