[usefulcat]

Seems like that would only help if the duration of the blast was less than 24 hours

[DavidSJ]

Rotation around the axis doesn't expose the northern hemisphere to the southern sky, nor vice versa.

[causality0]

That depends on the orientation with regard to the poles. If the source were directly over a pole, only fifty percent of the planet would be directly exposed. If it were over the equator, however, the whole planet would be, if it were a magic GRB that lasted way longer than usual.

[phyzome]

Or perhaps more like 12 hours, as half of the Earth would be exposed instantly.

But even then it depends on whether it's the direct radiation that's the issue or something more indirect (atmospheric changes, etc.)

[IAmGraydon]

The longest gamma ray bursts only last a few minutes.

[thfuran]

Just how many nines reduction from peak intensity after a few minutes are we talking? Because I'd imagine 0.01% of a nearby gamma ray burst would still be bad news.

[jiminymcmoogley]

doesn't this depend on the blast's origin relative to the Earth's axis?