Then I think religious people ought to thank astronomers for showing
them more of the greatness of God. Those who only thought of him as the
Creator of the three thousand stars, to be seen by the naked eye, could
not have such a notion of his vast power as those who know of millions
upon millions of suns.”
* * * * *
After this, James was left to digest such wonderful lessons. When his
first astonishment had passed away, his curiosity was excited to know
more about the distances of the stars, so that he might form a simpler
idea of the thing. He took, therefore, another occasion of bringing up
the subject in these words:--
“Father, do you really believe the stars are so far off?
I am obliged to believe many things I do not understand, upon the
testimony of trustworthy witnesses; but in this case I can form a
good guess of the truth. Do you remember what I once told you of the
parallax, or angle of observation of the sun or moon?
Yes. That of the moon was 57 minutes, and the sun 8-3/4 seconds. A
degree is 60 minutes, and a minute 60 seconds.
Very well. Then 57 minutes, or 3420 seconds, will be four hundred times
as much as the other. If the moon be 240,000 miles off, the sun will be
four hundred times further or 96,000,000.
But how do you get this parallax?
Distances are calculated by the angle made in looking at an object from
two places. The two lines of sight cross one another. A great base is
needed to view a distant object, or else no angle can be observed.
Astronomers take the diameter of the earth’s orbit.
That is twice ninety-five millions of miles.
With that base--that is, looking at a star from both sides of our
orbit, or at six months’ interval--we could get the two lines crossing
one another, and so making an angle. The further the object, the more
minute the angle. Only a few of the fixed stars could be observed in
this way, as they generally are too far off to give an angle.
I know an equilateral triangle has its three angles equal to two right
angles; and with ninety degrees for one right angle, each angle of the
triangle will have sixty degrees. But I suppose no star parallax could
be one degree.
No; nor a minute, the sixtieth part of one degree. When the object
makes an angle of a second, or sixtieth of a minute, from a base line
of one hundred and ninety millions of miles, the distance of the star
will be about twenty millions of millions of miles.
Is there any star making the second angle?
The _alpha_ of the Centaur is about that, and is one of the nearest of
fixed stars.
That the nearest to us, and yet so far! Do tell me the distance of some
others.
Public-domain text, read in full here on John Shaqi.
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