ry of the sun, and another glory of the moon,
and another glory of the stars: for one star differeth from
another star in glory."

The ancient Greek astronomers divided the stars according to their
brightness into six classes, or six "magnitudes," to use the modern
technical term. The average star of any particular magnitude gives about
two and a half times as much light as the average star of the next
magnitude. More exactly, the average first magnitude star gives one
hundred times the light of the average star of the sixth magnitude.

In a few instances we have been able to measure, in the very roughest
degree, the distances of stars; not a hundred stars have their
parallaxes known, and these have all been measured in the course of the
last century. And so far away are these stars, even the nearest of them,
that we do not express their distance from us in millions of miles; we
express it in the time that their light takes in travelling from them to
us. Now it takes light only one second to traverse 186,300 miles, and
yet it requires four and a third years for the light from the nearest
star to reach us. This is a star of the first magnitude, Alpha in the
constellation of the Centaur. The next nearest star is a faint one of
between the seventh and eighth magnitudes, and its light takes seven
years to come. From a sixth magnitude star in the constellation of the
Swan, the light requires eight years; and from Sirius, the brightest
star in the heavens, light requires eight and a half years. These four
stars are the nearest to us; from no other star, that we know of, does
light take less than ten years to travel; from the majority of those
whose distance we have succeeded in measuring, the light takes at least
twenty years.

To get some conception of what a "light-year" means, let us remember
that light could travel right round the earth at its equator seven times
in the space of a single second, and that there are 31,556,925 seconds
in a year. Light then could girdle the earth a thousand million times
whilst it comes from Alpha Centauri. Or we may put it another way. The
distance from Alpha Centauri exceeds the equator of the earth by as much
as this exceeds an inch and a half; or by as much as the distance from
London to Manchester exceeds the hundredth of an inch.

Of all the rest of the innumerable stars, as far as actual measurement
is concerned, for us, as for the Hebrews, they might all actually lie on