High Planetary Tilt Lowers Odds for Life?

If you think summer is too hot or winter unbearably cold, take solace that in the distant past seasons on our planet might have been much harsher. However, the advent of milder seasons did more than offer comfort, some scientists suggest. Subdued seasonality might be linked to the emergence of complex life on Earth around 600 million years ago. On alien worlds, extreme seasonal spikes and plunges in temperature could likewise determine whether life teems, scrapes by, or dies.

Seasons arise when the axis of a planet's spin is tilted relative to the plane of the planet's orbit. Recent research has suggested that a loss of axial tilt and its attendant seasonality, which helps moderate global temperatures, could doom extraterrestrial creatures. Scientists are also considering the opposite case: worlds where blazing summers and devastatingly frigid winters make the development of life with any complexity a long shot.