QOD: Why don’t stars explode?

Stars have a shelf life of billions of years. For the most part they are stable in a process called Hydrostatic equilibrium.

The Balance of Forces
Stars are constantly experiencing two opposing forces:

Gravity pulling inward – The star’s massive weight trying to collapse it
Pressure pushing outward – Heat and radiation from nuclear fusion in the core pushing out

These forces balance each other perfectly, keeping the star stable for millions to billions of years.

Why the Balance Holds
In a star’s core, hydrogen atoms fuse into helium, releasing enormous amounts of energy. This energy creates outward pressure that counteracts gravity’s inward pull. As long as the star has fuel to burn and maintains this balance, it remains stable.

When stars do explode it is called a supernova (there are two types):

Core-Collapsing supernova – this happens when a super massive star, we are talking about 10 times the mass of our star runs out of fuel. The core collapses in on itself and then unbelievably massive explodes outwards that can’t be contained.

Type Ia supernova – this occurs when a white dwarf start in a binary system (two stars that rotate around each other in close quarters) eats too much matter from the other start. The result is a thermonuclear explosion.

A supernova is one of the brightest and most powerful events in space. Often the result is a bright spot that can outshine an entire galaxy of starts (we are talking billions of stars). There is a star in the constellation Orion named Betelgeuse. It is showing signs that the star is relatively close (within 100,000 years or so). The star has already used up all of its fuel (Hydrogen) and it shows irregular dimming and brightening. We can also tell that it is fusing heavier elements in its core.

When Betelgeuse does go supernova, we will surely see it. It will be visible in the daytime and at night. In a previous post I was talking about distance. The light from Betelgeuse left over 650 light years away. So if it did go supernova, it went a long time ago and we are just seeing it now.

Back to the original question: Why do/don’t stars explode: