Asteroids and the Earth are both traveling in orbits around the Sun.
The Asteroids that cross the Earth's path are in highly eliptical
orbits, while the Earth is in a near circular orbit.
If you draw the two orbits on a piece of paper, they
intersect at two points, but notice that the two
orbits are not perpendicular to one another, and
the two points of intersections are also not perpendicular to
Also the speeds of the Earth and the Asteroids are not the same,
so the colission if and or when it occurs will be very
energetic. Energy = 1/2 Mass x Velocity Squared.
The probability that the Earth, and the Asteroid will be exactly
on the same plane of the ecliptic is very very small,
and the probability that it will collide exactly at 90 degrees,
while being exactly on the same plane of the ecliptic is
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