Monday’s fireball… What caused the light and the sound?


Many across Central Pennsylvania reported a loud sound and/or a bright flash just before 10:30pm Monday morning. Chris Vipond shared his security camera video seen above. There was a lot of speculation as to the cause of this event, but the American Meteor Society helped to confirm that what was seen was a bright meteor, also known as a fireball. As seen in the map below, we were not the only ones that saw this event.

No photo description available.

Observations were from Eastern Pennsylvania southward to the Richmond area. Putting together the reports, the path of the fireball was located high in the atmosphere over Virginia just southeast of Washington DC. You can see the estimated path with the blue line between the green and red locator. It seemed closer than that to witnesses around our area, but keep in mind that what you was was much higher in the atmosphere and visibility from such high events can be hundreds of miles.

After this event, there have been many questions about these fireballs, so let’s break down the science for you.

What causes the light we see?

  • All meteors (what we call shooting stars), including these fireballs, emit light because their temperature gets high enough to emit visible light. In fact, that’s why the sun sends visible light. These meteors are traveling at a rate of 25,000 mph to 160,000 mph as they enter the atmosphere. As they start to enter the atmosphere, the friction with air molecules causes the meteoroid to heat. It also starts to slow down, especially as it starts to reach the lower parts of the atmosphere. Because of this slowing, the meteor actually cools enough that it would not be visibly emitting light by the time it reaches the lower atmosphere. Therefore, while many people think the brightness means it should be close, actually if it were close to the ground, you would not see it.

What is the difference between a regular meteor and a fireball?

  • All fireballs are meteors, but not all meteors are fireballs. What is the difference? It’s the brightness. A fireball is brighter than the planet Venus.

What caused the sound we heard?

  • More people actually heard a loud explosion-like sound Monday evening than saw the light. In fact, it shook our television station and sounded like a loud close by firework.
  • The sound is not really an explosion but rather is a sonic boom. This comes because the meteor is travelling at the speed of sound.
  • Speaking of the speed of sound, it is much slower than light. This is why the sound came after the visual at the video at the top of this story.
  • Sometimes the sound can come minutes after the light of the fireball.

Where did this land?

  • It’s hard to believe, but the vast majority of fireballs never reach the ground. At least not more than the size of dust. The heat and friction breaks them apart way before reaching the ground.
  • On rare occasions there will be a rock that reaches the ground, at this point it is called a meteorite.
  • If there is a meteorite, it will have landed a good bit away from the light seen.

How rare is this?

  • It’s not that rare, we just got luck as to be where it can be seen.
  • Several thousand fireballs strike the atmosphere each day. Keep in mind that most of the earth is isolated and/or oceans. Therefore most occur that most happen where there is no one to see it. They also can be masked by daylight.
  • Once in a while they can be seen during the day. Such was the case where many in our region saw a daytime fireball in the early 2000s.

How big was this meteor?

  • Most of the bright meteors you seen in the sky are from objects that are the size of a nugget of Grapenut Cereal.
  • Some of the brightest and louder fireballs are larger, but still often start smaller than the size of a basketball. Still not big enough to reach the ground.

Where can I learn more?

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