Why Earth Needs an Atmosphere

The atmosphere supports conditions needed for life, but saying solar energy alone would kill all life is imprecise. Without an atmosphere, the surface would lose greenhouse heat retention and experience much larger day-night temperature contrasts; there would also be no ozone layer to absorb much of the biologically harmful ultraviolet radiation. Surface life would face critical changes in temperature and radiation, though specific outcomes would depend on the organism and location. [1–3]