How to destroy the Earth, part 4

4.
Cooked in a solar oven

You will need: Means for focusing a good few percent of the Sun's energy output directly on the Earth.

What I'm talking about here is: mirrors, and lots of them. Intercept several decent sized asteroids for raw materials and start cranking out kilometre-square sheets of lightweight reflective material (aluminised mylar, aluminium foil, nickel foil, iron foil or whatever you can scrape together). They need to be capable of changing focus direction at will because it is generally impossible to place things stationary in space and the relative positions of the Earth and Sun will be shifting as time passes, so attach a few manoeuvering thrusters and a communications and navigation system to each sheet.

Preliminary calculations suggest you would need roughly two trillion square kilometres of mirror.

Method: Command your focusing array to concentrate as much solar energy as you can directly on the Earth - perhaps on its core, perhaps at a point on its surface. So the theory goes, this will cause the Earth to generally increase in temperature until it completely boils away, becoming a gas cloud.

A variation on this method involves turning the Sun into a gigantic hydrogen gas laser.

Earth's final resting place: A gas cloud.

Feasibility rating: 3/10. The major problem here is: What's to stop the matter cooling and becoming a planet again? In fact, once the top layer of planet becomes gaseous, what would compel it to vent into space rather than remaining on the surface, absorbing more heat and preventing the lower layers from even being heated? Unless the amount of heat put in was really immense, all you'd get is a gas planet at best, and a temporary one at that. Moving the Earth towards the Sun (see later) is likely to be a far more viable method.

Source: This method suggested by Sean Timpa.