SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 45 
that 3072 shooting stars enter daily the limited air space which 
our eight observers watch only a few hours. 
In this figure the earth’s radius OA = 3959 miles. The are 
ezb indicates the level of air surface in which shooting: stars 
first appear. lLet.us eall it the surface of apparition. As 
previously shown, the height Az — 75 miles. Our eight ob- 
servers, flat on the ground, have their heads about the pole at A. 
Their lowest line of sight Ab, or Ae, is elevated 30 degrees. 
Therefore angle zAe — 60 degrees. During their vigils they 
see all shooting stars that enter the zone of apparition capping 
the funnel shaped space eAb. 
We must compute the area of that zone. The upper edge or 
rim of the funnel is a circle whose diameter is eb. The zone 
watched is that part of the air surface cut off by a horizontal 
_ plane through eb. It is called a zone of one base, and its area 
equals a circle whose radius is the distance ze. We must find 
that distance. In triangle eOA, angle at A being known, also 
the sides OA and Oe, we find eOA, or eOz = 18 47’ 47’. In 
triangle eOz, knowing angle eOz and sides Oc and Oz, we find 
ze — 12634 miles. A circle of this radius contains 50462 square 
miles. The watched zone of apparition then covers 50462 
square miles. 
How many times larger than that zone is the entire surface of 
apparition which envelopes the earth at a height of 75 miles? 
Its radius Oz = 3959 + 75 — 4034 miles. Its area therefore, is 
over 204 million square miles. This is fully 4052 times 50462 
square miles. That is, the area of the entire surface of appari- 
tion is 4052 times the area of the zone through which, as we 
have seen, enter daily 3072 shooting stars. Therefore, into the 
entire atmosphere enveloping the world there enter daily at 
last 4052 times 3072 shooting stars—in round numbers, 1215 
million. 
But had our eight observers held their vigils in the early 
morning before dawn, they would have counted more than 
double as many shooting stars per hour—indicating some 28 
million per day. 
Average the evening and the morning counts, and we find 
that the number of shooting stars which plunge into our atmos- 
phere daily is fully 20 million. 
Distribution 
The earth with its air envelope to a height of 75 miles, or 
simply the whole surface of apparition, is a globe whose radius 
is 4034 miles. The space through which it speeds daily 181% 
miles per second, is more than 114 million miles long. Its eross 
