It's all about energy. As in any impact kinetic energy is converted to heat, light, and sound, as well as other kinetic energy (air movement). To an object travelling at say 50km/sec, hitting something as dense as the earth's atmosphere is not much different to hitting a solid object.
Personally, I only heard the one boom (I was inside) which sounded something like either a huge thunderclap, or as I'd imagine an LPG tank explosion would sound.
What I found interesting was the single huge gust of wind (perhaps 100km/h) which shook the house at the same time. This I imagine was the compressed air front responsible for the "sonic boom".
Let's say it was 1m in diameter, it might weigh say 1 tonne. At 50km/sec, that's 5 x 10e7 kg.m/s.
Depending on surface area, attitude, and angle of attack, that could move a lot of air I guess.
BTW. Saw on tonight's news that a fragment (Not confirmed as genuine yet) about 100mm in size has been found in a farm field, but is apparently a little light (in weight) to be asteroidal.
My theory is that the Space Shuttle astronauts flushed the toilet and what we should be looking for is a frozen block of ****.
![Laughing :lol:](./images/smilies/icon_lol.gif)
(On this note Selden, you'll probably want to move the thread to purgatory
![Wink :wink:](./images/smilies/icon_wink.gif)
)