It is this leaning of the earth (23 1/2 degrees) that occasions summer and winter, and the different length of days and nights. If the earth turned round itself in a position perpendicular to the plane or level of the circle it moves in round the Sun, as a top turns round when it stands erect on the ground, the days and nights would be always of the same length, twelve hours day and twelve hours night, and the season would be uniformly the same throughout the year. Every time that a planet (our earth for example) turns round itself, it makes what we call day and night; and every time it goes entirely round the Sun, it makes what we call a year, consequently our world turns three hundred and sixty-five times round itself, in going once round the Sun. The names that the ancients gave to those six worlds, and which are still called by the same names, are Mercury, Venus, this world that we call ours, Mars, Jupiter, and Saturn. They appear larger to the eye than the stars, being many million miles nearer to our earth than any of the stars are. The planet Venus is that which is called the evening star, and sometimes the morning star, as she happens to set after, or rise before the Sun, which in either case is never more than three hours. The Sun as before said being the center, the planet or world nearest the Sun is Mercury; his distance from the Sun is thirty-four million miles, and he moves round in a circle always at that distance from the Sun, as a top may be supposed to spin round in the tract in which a horse goes in a mill. The second world is Venus; she is fifty-seven million miles distant from the Sun, and consequently moves round in a circle much greater than that of Mercury. The third world is this that we inhabit, and which is eighty-eight million miles distant from the Sun, and consequently moves round in a circle greater than that of Venus. The fourth world is Mars; he is distant from the sun one hundred and thirty-four million miles, and consequently moves round in a circle greater than that of our earth. The fifth is Jupiter; he is distant from the Sun five hundred and fifty-seven million miles, and consequently moves round in a circle greater than that of Mars. The sixth world is Saturn; he is distant from the Sun seven hundred and sixty-three million miles, and consequently moves round in a circle that surrounds the circles or orbits of all the other worlds or planets.