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The Question
(Submitted May 21, 1998)
Is there a possibility that a nearby star could go supernova and destroy
the earth? Or have other bad effects on us?
The Answer
To destroy the Earth itself, the Sun will have to go supernova
(which it never will).
If you are talking about the life on Earth, then there is a detailed
calculation of the risks due to a nearby supernova on the web:
http://stupendous.rit.edu/richmond/answers/snrisks.txt
The author concludes that a supernova has to be within 10 parsecs
(30 light years) or so to be dangerous to life on Earth. This is
because the atmosphere shields us from most dangerous radiations.
Astronauts in orbit may be in danger if a supernova is within 1000
parsecs or so.
No stars currently within 20 parsecs will go supernova within
the next few million years.
There are some indirect effects, though, which are harder to evaluate:
the possible effects on the Earth ozone layer is listed in the
article above. Additionally, according to one calculation,
the neutrino flux from a nearby supernova might heat up the Sun.
Best wishes,
Koji Mukai & Eric Christian
for Ask an Astrophysicist
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