Short answer
A nova is a stellar outburst that leaves the stars in its binary system intact; a supernova is a destructive stellar explosion. Supernovae include both massive-star core collapse and white-dwarf explosions, so they are not simply stronger versions of novae. A dense core can remain after core collapse. 1 2
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At a glance
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| Question | Nova | Supernova |
|---|---|---|
| Are the original stars destroyed? | No | Generally, the exploding star is destroyed as such |
| Must it involve a binary? | Yes | No |
| What pathways are described? | Binary-system outburst | Massive-star collapse; white-dwarf explosion |
| Can a dense core remain? | The stars survive | Usually after core collapse |
These are physical distinctions, not a classification based solely on the view from Earth. 1 2
What each thing is
A nova names an outburst occurring within a two-star system, rather than the destruction of that system’s stars. A supernova names an explosion with a fundamentally different outcome for the exploding star. The sources distinguish the categories by what happens to the star, not just by how dramatic the event looks. 1
Key differences
The supernova mechanism matters. In core collapse, a massive star loses the pressure support that resists gravity; collapse produces shock waves that expel outer material. In the white-dwarf pathway, excess accumulated matter or a collision with another white dwarf can trigger an explosion. These are distinct routes within the supernova category. 1 2
How to tell them apart
A useful identification rule is to ask whether the event leaves the original stars intact, then establish its mechanism. Do not classify it from an impressive sky appearance alone: the sources compare luminosities but also note that dust blocks many Milky Way supernovae. They do not supply a stand-alone visual test for an Earth observer. 1 2
Where they overlap
Both categories involve bright stellar outbursts, and both can occur in binaries. Even a white dwarf receiving matter from a companion is not, by itself, enough to separate them: the sources discuss companion-fed white dwarfs in connection with nova activity and with destructive supernova explosions. Setting alone does not establish the category. 1
Edge cases
A surviving dense core does not automatically make an explosion a nova. NASA’s core-collapse description usually leaves such a core alongside expanding hot gas. Here, saying a supernova destroys a star means that the original star does not survive intact—not that every part of it must disappear. 1 2
Why the distinction exists
The distinction preserves different physical outcomes and mechanisms behind superficially similar brightenings. It also keeps the supernova category broad enough to include both collapse and white-dwarf explosions. Observing across wavelengths helps researchers investigate these events beyond their visible appearance; NASA describes such work for both novae and supernovae. 1 2
Common misconceptions
A supernova is not merely a nova that crosses a brightness threshold. Nor does every supernova require an isolated massive star: white-dwarf explosions can arise in two-star systems. Conversely, finding two stars does not prove that an outburst is a nova, because binary systems can also produce supernovae. 1 2
Examples
Hypothetical case one: an outburst occurs in a close binary, and both stars survive intact. That fits the supplied nova distinction. Hypothetical case two: a massive star collapses, ejects its outer material, and leaves a dense core. That fits a core-collapse supernova despite the remnant. These cases apply physical outcomes rather than Earth-visible brightness. 1 2