The story of the sun, moon, and stars . hundred and eighty thousand earths, his weight is inproportion less. Our earth is about four times asdense as the sun. If her size were increased to thesuns size, her density being the same as now, shewould be very much heavier than the sun, and wouldattract much more strongly. Still, though the sun isof lighter materials than the earth, his immense sizegives him weight equal to seven hundred and fiftytimes as much as all the planets put together. The attraction on the surface of the sun is alsovery great—so great that we can hardly picture it toourselve
The story of the sun, moon, and stars . hundred and eighty thousand earths, his weight is inproportion less. Our earth is about four times asdense as the sun. If her size were increased to thesuns size, her density being the same as now, shewould be very much heavier than the sun, and wouldattract much more strongly. Still, though the sun isof lighter materials than the earth, his immense sizegives him weight equal to seven hundred and fiftytimes as much as all the planets put together. The attraction on the surface of the sun is alsovery great—so great that we can hardly picture it toourselves. If life exists there at all—supposing it YET MORE ABOUT THE SUN. 155 possible that any kind of life can be in such a fieryatmosphere—it must be life very different from anyknown in this world. A man who on earth weighsone hundred and sixty pounds, and walks lightly erect,would, on the sun, lie helplessly bound to the ground,crushed by his own overpowering weight. It is saidthat a cannon-ball, reposing on the sun, if lifted one. COMPARATIVE SIZE OF THE EARTH AND SUN. inch and allowed to fall, would dash against theground with a speed three times greater than that ofour fastest express-trains. For weight on earth ismerely caused by the amount of force with which theearth draws downward a body towards herself—aforce greater or less according to the density of thatbody. So weight on the sun would be immenselyincreased by his immensely greater power of at-traction. I56 STORY OF THE SUN, MOON, AND STARS. It is an interesting question how far the suns at-tractive influence reaches effectually through nearer a body is to the sun, the greater the at-traction which he exercises over it. At the distanceof the planet Mercury, a speed of twenty-nine mileseach second is needful to overcome or balance it suffi-ciently for the planet to remain in his orbit. At thedistance of the planet Neptune, about three mileseach second is enough. If a planet were journeyingat four time
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