Fortunately not very often - because if one does hit, it would be a major catastrophe.
1km
1km = 1,000m which is larger than 334m
There are 1000 metres in one kilometre. Therefore, this is larger than 334 metres.
1 kilometer is 1,000 meters. That is much larger than 224 meters.
one mile is longer than one kilometer
There have been about 300 identified Earth-crossing asteroids. The total number of asteroids that cross the Earth's orbit is estimated to be significantly greater than this; by one estimate, there are perhaps 1500 asteroids that are greater than 1km across, and 135,000 steroids that are greater than 100m across.
yes ,1km=100000cm 10km=1000000cm
Asteroids from 10m to 100m in diameter can cause national devastation (i.e. a country or state). Asteroids from 1km to 10km in diameter can cause global devastation (i.e. the world or several continents).
1km = 1000m 1km > 50m 1km is bigger
1km = 1000m520m/1km:= 520/1000 or 13/25 of 1km
100000cm = 1km 50cm = 1km/1000000cm/1km 0.00005km = 50cm 50cm < 1km
1km -450 = -449