If Eta Carinae becomes a supernova, how much of a radiation dose will earth get?

Question

Eta Carinae is a massive and unstable star about 8000 light years away.

Answer 1

8000LY = about 500,000,000 AU

It's said that a supernova explosion can outshine all the other stars in a galaxy combined. There are 400 billion stars in our Milky Way, let's say that Eta Carinae going boom would light up like 500 billion stars.

Assuming also that our sun is roughly of average luminosity.

Assuming also that the proportional increase in luminosity for a supernova is the same across the entire EM spectrum.

So the additional light/radiation that Earth would experience would be: (5*10^11) / [(5*10^8)^2] = .000002, or 1/500,000ths.

So even if the majority of the radiation was emitted as X-rays & gamma rays, Earth would not see a dangerous increase in radiation.

Answer 2

As a rough approximation (others can probably give you a better formula, but I'm first) divide 8000 light years by astronomical units (the distance of earth from the sun). Estimate that the radiation a hypothetical planet orbiting that star at 1 AU would be something like 100 million times what our sun puts out.

Now double the distance. The radiation is cut in half. Double it again. Cut the radiation in half again (1/4). Double the distance again, The radiation is cut again, to 1/8. This is called the inverse square law. Keep going till you run out of distance.

Your estimate will probably be within an order of magnitude of what anybody else's estimate will be. Close enough, for purposes of our discussion.

Answer 3

How long would it take the radiation to reach us if the star is 8000 light years away? 20 thousand years? Thirty?
Civilizations on our planet rise and fall within hundreds of years... technology is increasing at an amazing pace... in 20 thousand years...we will have found out if Christ will indeed return, or if mankind evolves into a different creature. There will be thousands of generations that pass after yourself - we will be the ancient past, it seems just too far away to even seriously consider. Let's focus on 500 years or less, which would be 200 light years or less, which amounts to a few hundred stars in or own galaxy. Life would me simpler.
:-)

Answer 4

In 4 billion years and counting, the Earth has been exposed to thousands if not millions of distant and probably much closer steller explosions and life continues on. Earth has never been completely devoid of life once it evolved.

An exploding star would have to be at least as close as the solar system's closest stellar neighbors in order to have a significant impact on life here.

There are some theories about extinction episodes linked to one.

Answer 5

The Earth will receive only a small amount of hard radiation from the explosion, not enough to cause too many mutations and such, but it will show on detectors like gamma ray detectors and the like. It will, however, give off a lot of light and that will brighten the nights quite a bit. It will be visible during the day and will be more than bright enough to cast shadows.


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cdf......that's approximately 506million AU's, so using the inverse square law, and your typical supernova luminosity of 25 billion solar luminosities, that's 25billion x (1/506million^2).

If we use your methods.