Our Earth, like Mercury, goes sometimes a little faster and sometimes a little more slowly. When nearer to the Sun she travels faster, and when farther off from him she travels more slowly. But the differences in her speed are much less than in Mercury’s, because her pathway is not so oval in shape, and so she is always more nearly at one distance from the Sun. Outside Earth’s pathway is that of MARS, the last of the Four Lesser Worlds. His untwinkling red gleam is easily seen. Not always in the east or west, like that of Mercury and Venus; but, like all the outer planets, in different parts of the sky at different times. Mars is much smaller than our Earth. He is only some 4,000 miles straight through. A big knitting-needle which might run just through him would have to be twice as long as one for the Moon, but only half as long as one for the Earth. It takes Mars about twenty-four hours and a half to spin once on his axis; so days and nights are much the same in length there as with us. His axis, too, seems to lean over very much as our Earth’s axis does, and that would give Mars seasons a good deal like ours. Only, as the year of Mars is almost as long as two Earthly years, his seasons would last much longer. Spring and summer, autumn and winter, would be each about five or six Earthly months in length. The distance of Mars from the Sun is about 140 millions of miles. So Venus is somewhere about twice as far off from the Sun as Mercury. The Earth is about three times as far as Mercury. Mars is more than four times as far as Mercury. Mars is a very interesting little world. Not so brilliant or lovely as Venus, but really more easy for us to study and examine. Venus seems to be so covered with masses of white clouds that we can see very little of the planet itself; but Mars is not covered with clouds. Mars never comes so near to us as Venus does. Only, unfortunately, Venus at her nearest cannot be seen at all, because her bright side is turned away from the Earth and towards the Sun. While Mars at his nearest, being _outside_ the Earth, can be looked upon nicely, for the Sun then shines full upon that side of Mars which is towards us. When we talk of “studying and examining” a world which never by any chance comes closer than 35 millions of miles away, we have to be careful. It does not do to guess at things, or to be in a hurry to settle what cannot be truly known. Even with the Moon we found that the biggest of telescopes cannot make her look very much less than one hundred miles away. But Mars is a great deal farther off than the Moon. Just think of the difference! The 240 _thousands_ of Moon-distance are changed into 35 _millions_ of miles for the distance of Mars. And the most powerful telescope cannot bring down those 35 millions of miles to less than about 35 thousands of miles.