By computing the difference, it becomes quite obvious that they were caused with a traveling object. And the distance from here's approximately 48 miles.
8 seconds sound clip from the The Thing from Another World movie soundboard.
You can hear this line at 00:14:52 in the Blu-ray version of the movie.
Quote context
[...]
- Here, at 6:14, it's moving upward. At 6:15, it drops to the earth and vanishes.
- A meteor might move almost horizontal to the earth, but never upward.
- How do you determine the distance to the point of impact from here?
- You lost me, but I'll take your word for it.
- One thing, doctor. 20,000 tons of steel is an awful lot of metal for an airplane.
- It is for the sort of airplane we know, captain.
- Redding will check every quarter hour.
[...]