Night Sky Gaze

Supernovas: The Biggest Fireworks Show in the Universe

A supernova is the death of a star. It’s also the most incredible, explosive event in the universe.

Supernovas are bright enough that they can easily be seen without a telescope. Chinese astronomers recorded a “guest star” that appeared in the sky in 185 AD.  Johannes Kepler and Tycho Brahe documented a supernova in the Milky Way back in 1604.

The most recent supernova we’ve been able to see on Earth occurred in 1987.

Supernovas and Massive Stars

In the life-cycle of a massive star, a supernova is the equivalent of the villain in a horror movie that pops up one last time before dying.

As a star runs out of hydrogen fuel to burn, the delicate balance between outward pressure and inward gravity is upset. The dying star’s core eventually collapses in on itself when gravity wins.

When that happens, the resulting shockwave blows the outer layers of the star into space. The supernova shines brighter than whole galaxies before it finally burns out.

Betelgeuse, the red supergiant that forms Orion’s right shoulder, is a prime candidate to go supernova. The star has been cooling and expanding for a long, long time, giving it the distinctive red hue. Eventually, it’ll lose the fight against gravity. When that happens, Betelgeuse will be as bright as the moon in the night sky!

Binary Star Systems Can Go Supernova, Too

The other type of supernova happens in a binary star system. In a binary system, two stars orbit each other. Think Luke’s home planet of Tatooine in Star Wars.

If at least one of those stars is a white dwarf–a planet-sized star that’s run out of fuel–it can steal matter from its companion star. Once the white dwarf has siphoned off enough mass, the mostly dead star core can reignite.

In other words, boom!

Could the Sun Go Supernova?

The Sun simply does not have enough mass to explode as a supernova. It would need to be at least 5 times more massive to go boom. And since the other type of supernova requires a binary star system, we’re safe.

Well, we’re safe from a supernova, at least. Astronomers predict that the Sun will eventually expand as it runs out of fuel, becoming a red giant. Unfortunately, the expanding Sun will devour Mercury and Venus–and possibly also the Earth. At the very least, it’ll fry our oceans and leave the planet a barren rock.

But that won’t happen for another 5-7 billion years, so don’t change your weekend plans.

Deana Adams

When Deana Adams was a kid, she begged her parents for a backyard telescope every birthday and Christmas until they finally caved. As an avid amateur stargazer, she memorized the constellations and hunted for the planets, collecting facts about astronomy the way other kids collected baseball cards or Barbies.

Deana is a contributing writer at NightSkyGaze. She still has her very first telescope.