## The Effect of a Nearby Supernova on Earth

The power output of a supernova is about
$10^{11}$
times the power output of the Sun, or
$10^{11} \times 3.84 \times 10^{26}=3.84 \times 10^{37}W$
. The minimum safe distance for a supernova is said to be 50 light years. How will a supernova at this minimum distance affect the Earth?
The distance of the supernova in metres is 50 light years or
$d=50 \times 9.46 \times 9.46 \times 10^{15}=4.73 \times 10^{17}$
m.
The intensity of radiation from the supernova at the Earth is
$I=\frac{L}{4 \pi d^2}=\frac{3.84 \times 10^{37}}{4 \pi \times (4.73 \times 10^{17})^2}=13.37 W/m^2$
.
This is only about 1% of the intensity of the Sun's radiation received at the Earth's surface (1358 W).