QQQ has huge tech exposure, but it is not a 'tech fund' in the pure sense either. The fund's arcane weighting rules further distance it from anything close to plain vanilla large-cap or pure-play tech coverage.
During the time when Earth was forming and was in a molten state, heavy materials like iron and nickel sank to the center of the Earth's mass and lighter materials floated to the surface of the mass. The very center of what we call the core, is solid in the middle because of the increased pressure in that region.
At the center of the Earth lies a two-part core. The inner part is about the size of our moon, Marone says, and has a density of essentially steel.. The outer core surrounding it is an ocean of liquid metal 2,300 kilometers thick. The Earth's rotation makes this ocean flow and swirl, and the moving metal generates the planet's magnetic field. Most of Earth's heat is stored in the mantle, Marone says, and there are four sources that keep it hot. First, there's the heat left over from when gravity first condensed a planet from the cloud of hot gases and particles in pre-Earth space.