Sure seems like we’ve had more than our fair share of bollides this weekend (Russia, Cuba, and San Francisco to name a few). Guess what? I THOUGHT SO TOO. But I was also skeptical. So I asked the scientists I trust* and scientists who specialize in this. They said that we ARE NOT experiencing an apocalypse or really even an increase.
1. Please go read my blogfather, Phil Plait’s, article about this.
The rest of my article is mostly in addition to what he’s already said.
The Frequency Illusion
In popular parlance this is also called the Baader-Meinhof Phenomenon, but the sources on that name are a bit questionable, so I’ll call it the Frequency Illusion.
You know how when you learn a new word, like “brobdingnagian,” suddenly you begin to see that word everywhere? (Perhaps brobdingnagian is a poor choice, it’s just the newest word I’ve learned.) How about The Great Gatsby? I haven’t thought about The Great Gatsby in years and suddenly there’s a new DiCaprio movie coming out and it was jut mentioned in the novel I’m reading. For my husband this week it’s the word “Trypophobia.”
Anyway, that’s the Frequency Illusion. Your mind is keyed into something, and you notice it everywhere. We’ve been hyperaware of asteroids and meteors this weekend, so more people are noticing and reporting the ones that normally occur. The media too is taking special note which is helping us notice these seemingly-extra occurrences.
The asteroid 2012 DA14 and the spectacular and devastating bollide over Russia are a coincidence. Literally a cosmic coincidence. They are unrelated.
The bollides since then have been a normal part of our everyday lives here on Earth, you just haven’t been noticing them regularly.
Bollides are Normal?
“Alice, I don’t believe you. Are you saying the bollide over Russia was normal? I don’t think hundreds of people are normally injured in sonic booms from meteors in our atmosphere.”
You’re right about that. Fireballs/Bollides/Meteors as large and powerful as the one over Chelyabinsk tend to happen once every 100-ish years. That doesn’t mean there won’t be one tomorrow, or in 50 years. On average they happen once every 100 years.
Fireballs tend to happen for objects about the size of a basketball, and those hit the Earth about once a day. Again, you can easily have two or ten in one day, as well as several days without one, but on average they happen once a day. This is what the meteors over Cuba and San Francisco were: normal daily bollides.
Fund the search for near earth objects.
I see how you might be confused. I’ve used several words interchangeably, and those that I haven’t are minutely different than each other.
- Comet — an ice and rock body in space.
- Asteroid — a smallish rocky body in space. Smaller than a planet or a Moon, larger than a house usually.
- Meteoroid — a tiny rocky object in space, usually sand-sized but up to the size of a house.
- Meteor — when a meteoroid impacts the Earth’s atmosphere it incinerates. We see them and know them as shooting stars.
- Meteorite — when a piece of a meteor survives the Earth’s atmosphere and impacts the Earth’s surface.
- Bollide — an especially bright or exploding meteor. (This is the astronomy definition, the geology definition is different, but doesn’t apply here)
- Fireball — an especially bright or exploding meteor. (Mm-hmm, pretty much the same as a bollide.)
I got my statistics from Yeoman’s Top Ten on NASA JPL’s Asteroid Watch.
Of course, Phil’s “The Sky is Falling… or is it?” article is also great.
Vocabulary reference from NASA’s Near Earth Object program.
~ A l i c e !
*”Hey Alice, Phil just posted something a day or two ago that he later admitted was wrong. Why do you trust him?” That’s why. Scientists admit when they’re wrong and change their views as the evidence changes. This is harder to do than you might think, so keep practicing. I keep practicing too.