Plural of “nebula”

The plural of nebula is nebulae (some dictionaries also accept nebulas).

Why

"Nebula" is Latin for "mist," "cloud," or "vapor," and like "alumna," it's a first-declension feminine noun whose classical plural is "nebulae." Astronomers adopted the word in the 17th and 18th centuries to describe the fuzzy, cloud-like patches of light they saw through early telescopes, long before they understood that some of these "nebulae" were actually distant galaxies rather than clouds of gas within our own.

As telescopes improved and astronomy became a more mainstream subject of popular science writing, "nebulas" emerged as a genuinely accepted alternative plural, particularly in casual or popular astronomy writing, while "nebulae" has remained the more common choice in academic and professional astrophysics — a split that closely parallels the technical/general divide seen with "focus/foci" and "focuses."

Usage note

In a research paper or planetarium show aimed at a general audience, either "nebulae" or "nebulas" reads as acceptable, with "nebulae" carrying slightly more scientific formality; in truly technical astrophysics literature, "nebulae" remains the safer default.

Science fiction and popular culture have helped popularize "nebulas" specifically, since many films, games, and novels aimed at general audiences favor the simpler, more phonetically obvious English plural over the Latin form, contributing to its wider acceptance outside professional astronomy. Some of the most photographed nebulae, like the Orion Nebula, are visible even through amateur telescopes, which has made "nebulae" (or "nebulas," in more casual astronomy writing) one of the more publicly recognized Latin-derived plurals in everyday English, encountered far more often by ordinary readers than words like "corpora" or "genera" that stay confined to specialist fields.

Common real mistakes

Writers occasionally invent "nebuli," incorrectly applying the masculine -us/-i pattern to a feminine -a noun — "nebula" is feminine, following the -a/-ae pattern like "alumna," not the -us/-i pattern like "focus" or "cactus."

The wider pattern

"Nebula" and "alumna" share an identical grammatical story: both are Latin first-declension feminine nouns pluralizing in -ae, though "nebula" shows notably more openness to a regularized "-s" alternative than "alumna" does, likely because astronomy writing reaches a much broader general audience than most academic institutional writing about alumnae does. The famous Hubble Space Telescope images of nebulae, particularly the "Pillars of Creation" photograph of the Eagle Nebula, did more than almost anything else to popularize the word among general audiences worldwide, making "nebulae" one of the rare Latin-derived scientific plurals most non-scientists have actually encountered directly.

Examples

• The telescope captured images of three distant nebulae in a single frame.
• Astronomers cataloged dozens of nebulas visible from the southern hemisphere.
• Several nebulae mark the remnants of stars that exploded millennia ago.
• The planetarium show featured stunning footage of colorful nebulae.
• New nebulas are still being discovered as telescope resolution improves.
• The star chart labeled each of the visible nebulae by catalog number.
• Two overlapping nebulae created an unusually bright patch in the night sky.
• Her photography project focuses entirely on deep-sky nebulas.
• Astrophysicists study how nebulae eventually collapse to form new stars.
• The documentary compared nebulae captured by telescopes decades apart.
• Amateur astronomers photographed two nebulae during the same clear night.
• The observatory's new instrument can detect faint nebulas invisible before.
• Several nebulae in the image were later confirmed to be forming new stars.
• The planetarium's dome show cycled through a dozen striking nebulae.
• The Hubble images of distant nebulae became instantly iconic worldwide.
• The planetarium compared nebulae at very different stages of stellar formation.
• Two newly cataloged nebulae were named after the astronomers who found them.
• Amateur photographers now capture nebulae using surprisingly affordable equipment.
• The telescope's newest images revealed nebulae never photographed before.
• Two nebulae appeared to overlap from Earth's vantage point.
• The observatory added new instruments specifically to study distant nebulae.
• Two overlapping nebulae created a striking, colorful cloud in the image.