How Could The World End In One Day?

[ZedBloke]

Ok in tandem with my news question I would like to get your ideas on how the world could end in one day and also what we mean by the world ending, I mean are we talking about the ending of life or the destruction of the whole planet? I'd say the former would take to long and the latter would have to be something cataclysmic like being to close to a GRB or a Supernova, possible a solar flare could vaporise the whole planet if we got closer to the sun.

[Teddio]

A collision with a large body such as the Moon or Mars would effectively reform the Earth, producing a large molten blob and other orbiting debris. On a lighter note (forgive !) the Winter Solstice occurred this morning at 11.11 so we have six months of lengthening days to look forward to.

[jake-the-peg]

Well lets see - Gamma Ray Bursts are thought to often associate with Supernovae so I'd consider them together - In principal yes a close by one could wipe out all life in a day but I don't think there are any candidates near enough.

A mantle plume such as that posited for the Deccan Traps is another candidate although whether that could actually manage it in 1 day might be stretching it a bit - ditto supervolcano (very similar concepts)

Obviously a large body impact as previously mentioned but no real candidates here either.

Thats about all I can think of

[mibn2cweus]

I would think a wandering black hole could do the job . . .

[wildwood]

I can assure you it isn't going to happen! It is 10.38am 22nd where I am at the moment so that's how I know. lol

[modeller]

If the world was going to end on the 21st would it happen in stages starting off in the far east and then as the world rotates gradually engulf the rest of the world.

[atalanta]

A colossal escape of methane might wipe out a lot of the earth's population. If there is ( as scientists believe) a vast amount of methane trapped in clathrates under the world's ice, it could be released in a huge burst, and it could catch fire. ( you can't breathe methane, by the way, even if it doesn't catch fire.)
There is the alternative of an expected monster landslip in the Atlantic which would send one undreamed-of supercolossal tsunami (or several ) rushing towards the US and rebounding onto all Atlantic coasts. Could be tomorrow, could be 5,000 years away. This could easily inundate all land up to at least 30 miles inland, destroying communications, buildings, roads, farmland and essential services. The sweep of the tsunami/s would reach and devastate all coasts of the Atlantic, including western-facing UK coasts, Ireland, Iceland. Portugal, France, Greenland, etc. It could sweep into the North sea and the Caribbean, and also probably along the north coast of South America. All islands in its path would be annihilated. The Panama canal could be wrecked.
This might not destroy all human life, but the repercussions of this could cause total world economic meltdown.
But if you are thinking of a solar flare - it would have to last over 24 hours in order to destroy all exposed life on earth - to make sure it lasted until the earth had turned at least once on its axis. We'd all fry, unless we were down deep mines, but the auroras would be magnificent !