Tuesday, April 20, 2010


The space shuttle, Discovery passed overhead this morning. I didn't see it, but I know it did because Rachel heard the sonic boom. She thought it was an explosion. When I told her that I'd driven the last mile to work with the windows down and the radio off in expectation she realized that she'd heard it. I was disappointed not to hear it myself.

I had to do a little research to be able to explain the boom to her. I haven't heard one since I was a teenager and I'd forgotten the cause. In case you have too, here's a quick refresher course: the boom occurs when the sound barrier is broken in supersonic flight. The object passing through the air forms pressure waves in front of and behind the object. These waves travel at the speed of sound. When the plane or shuttle travels faster than the speed of sound the waves are compressed together into a shock wave and the boom occurs. (it's really more complicated than this, so just call my explanation Sonic Booms for Dummys)

This probably explains why Rachel heard it at her home, but why I was unable to at work:

Since the boom is being generated continually as long as the aircraft is supersonic, it fills out a narrow path on the ground following the aircraft's flight path, a bit like an unrolling celebrity carpet and hence known as the "boom carpet". Its width depends on the altitude of the aircraft.

I suppose I wasn't in the red carpet area.

By the middle of 1971 sonic booms had been outlawed by Congress over populated areas.

An interesting tidbit I picked up while reading up on the subject today is that the sound created when a bullwhip is cracked is a small sonic boom. The end of the whip, which is known as the cracker, moves faster than the speed of sound when the whip is wielded properly.

So there you have it....the little that I know on the subject.


  1. I so enjoyed reading this! I love facts about science, so thiswas wonderful.;)
    Particularly as this was one of the last flights (if not the last?) of the space shuttle.
    I think I heard some sort of a boom, but probably not a sonic one, once when I vacationed on Cocoa Beach in Florida. The shuttle lift off as in the night, which I was unaware off, and I awoke suddenly in the hotel room due to a loud boom, that sounded like an explosion.;) It was first in the morning that we got told that there was a shuttle launch.;)

  2. I had just read we were down to the last of the flights. I am sad to see that era end.
    VERY interesting facts!

  3. I've always wondered about the science of it. My sister and niece who live in Florida both heard it yesterday, too.

  4. very very cool....i was out of the zone too

  5. What an interesting post. And I had no idea about the sound of a whip. Too bad you didn't get to hear the BOOM!

  6. I heard it! I didn't know what it was... first I thought something fell on the house, then I thought something in the attic fell, then I thought someone was in the attic... called the husband and he said, "It was the shuttle." Phew, I was relieved to know that no one was in the attic!

  7. Fascinating .. I had no idea Discovery flew low enough to make a sonic boom

  8. ..very interesting....it does make the world seem smaller to know so many can hear the same sonic boom. I seem to remember hearing sonic booms on a regular basis...can that be true? or am I remembering something else...

  9. Fascinating post Steviewren. When I lived in London, every evening at the same time I would hear the sonic boom of the late lamented Concorde going over en route to Gatwick Airport. It was an incredibe sound.


  10. Great post - you're such a fabulous, curious person - I love that! I was at an air show last year when a jet was doing a fly-by of the crowd and accidentally went a teensy bit supersonic on us...I'd heard it before, but my boys hadn't, and it's all they could talk about for the rest of the day!

  11. Interesting! I just read today that the military will be testing an unmanned plane that takes off, flies into space and comes back to land just like a conventional aircraft.

    Successor to the shuttle, perhaps??


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  13. BOOM!! Thanks for the info...hope you are having a fine sunny day!
    Let's just crack the ole whip..hee hee. :) The Bach

  14. So interesting, Stevie!

    The supersonic shuttle to France used to fly in and out of Kennedy airport and its flight path was over my neighborhood. I remember there was much discussion about not allowing it to reach the speed of sonic boom until it cleared populated areas. I love to see it fly over even though it made a lot of noise. It looked like a giant bird!

  15. Yes, the boom from the shuttles always shakes our house! Gets us almost every time, as for a second we think there has been an explosion or even that a car crashed in to our house, and then someone remembers a shuttle is coming back. So we can see them take off from our house, and hear them return. Or, we could...

  16. indiana jones is a great action movie i like


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