Bad Astronomy: Misconceptions and Misuses Revealed, from ...

134 SKIES AT NIGHT ARE BIG AND BRIGHT
Why don’t I believe it was a meteorite? Well, that’s a tale of
bad astronomy.
PPP
I’ve always felt sorry for small meteors.
A given meteoroid may spend billions of years orbiting the
Sun, perhaps first as part of a magnificent comet or an asteroid.
Finally, after countless times around the Sun, its path intersects the
Earth. It closes in on the Earth at a velocity that can be as high
as 100 kilometers (60 miles) per second. Upon contact with our
atmosphere, the tremendous speed is converted to heat, and, unless
the meteoroid is too big (say, bigger than a breadbox), that heat
vaporizes the tiny rock.
From our vantage point on the Earth’s surface, the meteoroid
generates a bright streak that may or may not be seen by human
eyes. After all those billions of years, the life of that small rock is
over in a few seconds, and no one might even see it.
But its story doesn’t end there. When I am asked to name the
most common example of bad astronomy, I almost always answer:
meteors. Nearly everyone who is capable has seen a meteor flashing
across the sky, yet, ironically, most people don’t understand
them at all.
Worse, even the naming of the phenomenon gets confused.
Some people call them “shooting stars,” but of course they aren’t
really stars. In chapter 3, “Idiom’s Delight,” I go over the three
names describing the various stages of the rock: The solid part is
called a meteoroid both while out in space and passing through
our atmosphere, the glow of the meteoroid as it passes through the
atmosphere is called a meteor, and it’s a meteorite when (or if) it
hits the ground.
But giving them names doesn’t help much. We need to know
what’s going on during those stages.
A meteoroid starts out life as part of a bigger body, usually as
either a comet or an asteroid. Asteroids can collide with each other,
violently flinging out material or, in a worst-case scenario, shattering
the parent body completely. Either way, you get debris going off
rapidly in all directions. That debris can take on new orbits, where