Tunguska-Sized Asteroids Impacts Not So Common

JoeGee writes "MSNBC.com is reporting that a new study aided by data from U.S. Military satellites is causing scientists to revise the frequency of Tunguska-like impacts downward. Military satellites used to detect rocket launches and/or nuclear flashes are also good at monitoring the frequency of flashes in the atmosphere caused by ten meter to one meter sized objects burning up in our atmosphere. The study has concluded that Earth encounters much less interplanetary debris than was previously thought, and Tunguska-scale events only occur on average of once every millenium."

Comments

Huh?

[Daniel Dvorkin]

So if I read the article right, what they're saying is that because only X meteors of a given size hit Earth in a given period, only Y meteors of a much bigger size will hit Earth in a much longer period? How do they know that Y has any relation at all to X?