Huh, I didn't know that, and now I have a great mental picture to accompany that fact.
For anyone who skimmed and is wondering "How long before another mass extinction, according to this theory?", the answer is in the last sentence (on page 2): we've still got 10 million good years.
First we must survive ourselves. The earths immediate problems are nuclear weapons and human generated climate change.
https://news.nationalgeographic.com/news/2009/04/090403-gamm...
and
https://astrobiology.nasa.gov/news/how-deadly-would-a-nearby...
BUT, such events are (apparently) every billion years or so...
Source: former astrophysicist. Also if I remember correctly, the Wikipedia article on grbs is actually decent. (Edit: overstated things - need coffee, I suppose)
I do have a degree, though, so it's purely a matter of perspective.
Mars, venus, and mercury have next to no field, earth has a moderate field, and all our gas giants have very strong fields.
Some of the gas giant moons are attractive since the gravitational effects on the moons can create geo-thermal energy. Pair a large planet with a strong magnetic field and energy created from gravity and we might have something interesting worth exploring.
I do not think this is perfect though, due to the size of our atmosphere we are shielded from meteorites,, this might not be the case of these moons. We would need to consider making some way to protect ourselves like harvesting ore from surrounding areas. Even then this might not stop large collisions.
However, if you assumed that we were able to go the bottom of the ocean, transporting supplies there would be much easier than transporting supplies to Mars.
Except we reached it four times since 1960 : https://en.wikipedia.org/wiki/Mariana_Trench#Descents
My Inc. article asks why we think we will solve problems off Earth that we haven't on Earth. Or if we think we can solve them there, why don't we solve them here first?
If we want to get to Mars, probably the best start is to solve the problems we have here first.
Furthermore, it is a straw man, because nobody actually believes that we should give up on Earth. You cited a number of headlines attributing this position to people like Elon Musk and Steven Hawking, when a quick reading of their actual quotes shows that they do not actually say what the headlines claim (Musk also runs a clean energy company for Pete’s sake—doesn’t sound like he wants to give up on Earth). I really want to believe that you wrote your article in good faith, but that means I must believe you did not read the articles you linked as evidence.
Redundancy doesn't fix problems but it cushions the failure case. There are numerous ways Earth could be wiped out in a way we can't defend against.
Those migrations didn't bring utopia, either to the participants or the rest of humanity.
We'd do better to build out some element of human society underground, if interstellar radiation is our fear.
Actually, water is very good at stopping radiation, so if there was a massive gamma ray burst that killed all surface life on Earth, some small groups of humans would survive: deployed submarine crews.
They'd also help species survivability in the event of some extinction-level asteroids, climate change, or interstellar radiation.
I think it's an even money bet whether it'd be easier to build a comfortable habitat for x people underwater or in space (for most definitions of comfort, x, and space).