Five amazing facts about supernovae

They’re bright and they’re violent but what else do we know about these stellar explosions?

An artist's impression of a supernova explosion. Image Credit: ESO

An artist’s impression of a supernova. Image Credit: ESO

1. Approximately one supernova occurs every second. Supernovae happen more often than you might think: one occurs somewhere in the universe every second. However, the Milky Way only has an average of two supernovae per century and trying to spot one as it happens is still very tricky. The last one directly observed in our galaxy was over 400 years ago and its namesake, Johannes Kepler, considered SN 1604 a new type of star at the time.

2. Most chemical elements are made in a supernova. The normal process inside stars, stellar nucleosynthesis, fuses hydrogen to create the elements, from helium through the periodic table to iron. To create the heavier elements through to uranium, however, requires something exponentially hotter and more energetic even than the core of a star – those forces typically found in the instant of a supernova.

3. They’re brighter than a galaxy. For a short period of time, a single supernova can easily outshine an entire galaxy of stars, releasing as much energy in a single burst as our Sun will in its entire, 10 billion-year lifespan.

4. Not all supernovae destroy stars. Some stellar explosions don’t destroy their progenitor stars: these are known as stellar impostors and they’re not true supernovae, although they’re easily mistaken as one. Rather, they’re a type of especially powerful nova – a phenomenon that causes a star to release large amounts of energy and brighten significantly for a short period.

5. Supernovae can create incredibly beautiful remnants. The result of this immense and apparently destructive force is often quite stunning. Some of the most famous stellar objects that we know of today – the go-to targets for astronomers – were created by supernovae that occurred hundreds or thousands of years ago. These classic sights include the Crab Nebula (M1) and Tycho’s Supernova Remnant (SN 1572).

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