Answers

How can Space Shuttle Orbiters enter the atmosphere without being vaporised like a meteoroid?

The black tiles on the underside of the shuttle heat up to 1,620° C and radiate away the energy as infra red waves. They also have a melting point higher than meteorites.

The orbiter does not take a direct line through the atmosphere. Instead it banks into wide S-shaped curves. This increases the time for deceleration (by 30 times compared to a meteorite) and decreases the energy conversion rate (again by 30 times). The tiles are able to shed heat at this rate so that the orbiter does not continue to heat up.

When would you expect to see more meteors – early evening or early morning?

Early morning. The combined speed of the Earth's and meteorite's orbit in a head on collision create more heat and a brighter meteor.

When would you expect most meteorites to land – early evening or early morning?

Early evening. Just like a rear collision on the road, the Earth's orbital speed results in a slower collision, less heat is transferred and there is more chance the core of a meteoroid will survive entry.

What is the maximum collision speed between a meteoroid and the Earth?

100km/sec - a little more when you add on the spin of the Earth and acceleration due to the gravitational attraction of the Earth.

People have picked up meteorites just after they land and report that they are only warm to the touch despite having a glassy covering created by intense heat only a minute before. Why do they cool so quickly?

Before it enters the Earth's atmosphere, a meteoroid's temperature is only a few degrees above absolute zero (-270oC). The heating and melting of the outer parts of the rock takes only a few seconds; not enough times for it to be conducted into the core. During the minute or so the surviving meteorite descends at terminal velocity (150-250m/s), the heat on its surface has time to spread into its cold centre by conduction, leaving the overall temperature of the meteorite not much more than the human body.