Nebulous star

At first he was uncertain whether he was seeing a comet or a "nebulous star," but he dismissed the possibility of it being a comet when the object's position remained unchanged during succeeding nights.

What caught his attention on this evening was what he described as a "curious either Nebulous Star or perhaps a Comet." The object, which had been observed at various times by other astronomers without them distinguishing its odd nature, was neither a nebulous star or a comet, but rather the first planet to be discovered in recorded history.

Discovered by the Italian astronomer Giovanni Maraldi on 1746 Sept 7 while looking for de Cheseaux' comet (he also discovered M2 a few days later), he described it as 'A nebulous star, fairly bright and composed of many stars.' It was not observed by Messier until 1764.

It was on a Tuesday, March 13, 1981, that a professional musician and amateur astronomer named William Herschel observed through his telescope what he described as "a curious either nebulous star or perhaps a comet." Determining that it was in fact neither took some time.

While searching Eridanus for comets with his 4 1/2-inch Henry Fitz refractor in 1859, he encountered a "most conspicuous nebulous star visible from this latitude." He assumed "this wonderful object" must be well known, until he saw that it wasn't included in John Herschel's 1864 General Catalogue of Nebulae and Clusters of Stars.

At first Maraldi mistook this object for the comet, but then he realized that it was another "nebulous star," like the one he'd found four nights before--the globular cluster M15 in Pegasus.

The cluster's discovery predates Lacaille by nearly a millennium, having been noted around AD 964 by the Persian astronomer al-Sufi, who described its naked-eye appearance as a "nebulous star." Lacaille elaborated somewhat, noting that through his small telescope it appeared as a "small heap of stars."

In his 1784 catalog Charles Messier described his 40th object as "two stars very close to one another and very small, placed at the root of the great Bear's tail." Messier's position corresponds to just such a star pair, so there's no reason to consider anything "missing." He noted this double while searching for a "nebulous star" reported by Johannes Hevelius.

M11 was discovered in 1681 by Berlin astronomer Gottfried Kirch, who called it a nebulous star. A quote often attributed to Kirch, but actually from a 1715 paper by Edmond Halley, specifically mentions M11's foreground star: "It is of its self but a small obscure Spot, but has a Star that shines through it, which makes it the more luminous." In 1733 English clergyman William Derham laid claim to being the first to resolve the cluster's fainter stars, but he may have been referring to the Scutum Starcloud as a whole.

His journal record for his first sighting on Tuesday, March 13, 1781, documents his suspicion: "In the quartile near [Zeta] Tauri the lowest of the two is a curious either Nebulous Star or perhaps a Comet." Four nights later, Herschel observed it again.

H 1-70 VIR [NGC 5634]: Beautiful lacery of nebulous stars.

William Herschel picked up NCC 2392 in a January 1787 sweep, adding it to the list of "nebulous stars" spotted through his 18.7-inch speculum reflector.