OCR Text |
Show Atmosphere of the Planets. Tho iitmoaphero of a world depends on Its gravitation. Oases tend to diffuse dif-fuse Into space, unless retained by adenunte attraction. Our earth can hardly retain so light and mobile a gas as hydrogen; Mars may hnvu difficulty dif-ficulty In retaining the less mobile vapor of water; but the gravitation of the moon Is too slight to retain any known gas. hence she has no atmosphere atmos-phere or water. Yet this Is not huIII-dent huIII-dent reason for assuming the absence of life. |