magnificent globe diffuses heat and light to all the
other planets.

Without the light and heat of the Sun no life would now be, or in the
past have been, possible on this Earth, or any other planet of the solar
system.

The eight planets of the solar system are divided into four inferior and
four superior.

The inferior planets are Mercury, Venus, the Earth, and Mars. The
superior are Jupiter, Saturn, Uranus, and Neptune.

The diameters of the smaller planets are as follow: Mercury, 3,008
miles; Mars, 5,000 miles; Venus, 7,480 miles; the Earth, 7,926 miles.

The diameters of the large planets are: Jupiter, 88,439 miles; Saturn,
75,036 miles; Neptune, 37,205 miles; Uranus, 30,875 miles.

The volume of Jupiter is 1,389 times, of Saturn 848 times, of Neptune
103 times, and of Uranus 59 times the volume of the Earth.

The mean distances from the Sun are: Mercury, 36 million miles; Venus,
67 million miles; the Earth, 93 million miles; Mars, 141 million miles;
Jupiter, 483 million miles; Saturn, 886 million miles; Uranus, 1,782
million miles; Neptune, 2,792 million miles.

To give an idea of the meaning of these distances, I may say that a
train travelling night and day at 60 miles an hour would take quite 176
years to come from the Sun to the Earth.

The same train, at the same speed, would be 5,280 years in travelling
from the Sun to Neptune.

Reckoning that Neptune is the outermost planet of the solar system, that
system would have a diameter of 5,584 millions of miles.

If we made a chart of the solar system on a scale of 1 inch to a million
miles, we should need a sheet of paper 465 feet 4 inches wide. On this
sheet the Sun would have a diameter of less than 1 inch, and the Earth
would be about the size of a pin-prick.

If an express train, going at 60 miles an hour, had to travel round the
Earth's orbit, it would be more than 1,000 years on the journey. If the
Earth moved no faster, our winter would last more than 250 years. But
in the solar system the speeds are as wonderful as the sizes. The Earth
turns upon its axis at the rate of 1,000 miles an hour, and travels in
its orbit round the Sun at the rate of more than 1,000 miles a minute,
or 66,000 miles an hour.

So much for the size of the solar system. It consists of a Sun and eight
planets, and the outer planet's orbit is one of 5,584 millions of miles
in diameter, which it would take an express train, at 60 miles an hour,
10,560 years to cross.