as in Fig. 30. Looked for from some of the stars about us, the
sun could not be seen at all. Indeed, seen from the earth, it is
not always the same size, because the distance is not always the
same. If we represent the size of the sun by one thousand on the
23d of September or 21st of March, it would be represented by nine
hundred and sixty-seven on the 1st of July, and by one thousand
and thirty-four on the 1st of January.

[Illustration: Fig. 30.--Relative Size of Sun as seen from Different
Planets.]

We sometimes speak of the sun as having a diameter of 860,000 miles.
We mean that that is the extent of the body as soon by the eye.
But that is a small part of its real diameter. So we say the earth
has an equatorial diameter of 7925-1/2 miles, and a polar one of
7899. But the air is as much a part of the earth as the rocks are.
The electric currents are as much a part of the [Page 79] earth as
the ores and mountains they traverse. What the diameter of the earth
is, including these, no man can tell. We used to say the air
extended forty-five miles, but we now know that it reaches vastly
farther. So of the sun, we might almost say that its diameter is
infinite, for its light and heat reach beyond our measurement. Its
living, throbbing heart sends out pulsations, keeping all space full
of its tides of living light.

[Page 80]
[Illustration: Fig. 31.--Zodiacal Light.]

We might say with evident truth that the far-off planets are a
part of the sun, since the space they traverse is filled with the