New research is helping to clarify ways a planet’s
orbit affects habitability.
ESA, NASA, and L. Calcada (ESO for STScI)
Earth is literally
inclined to be habitable. After running 93
simulations, NASA-funded researchers have gained a clearer understanding of the
parameters that make the orbits of Earth-like planets suitable for land-based
lifeforms to thrive.
The length of our planet’s day, the tilt
of its axis, and other orbital parameters ensure that the seasons, sunlight,
and temperatures across the surface vary within ranges that are amenable for
life as we know it. A larger or smaller orbit, faster or slower spin, or
significantly different tilt could make conditions more difficult for emerging
life on land. Scientists are now looking at Earth’s orbital parameters to help
narrow the search for habitable planets beyond our solar system.
The researchers have found that there’s
more to habitability than orbiting within the “Goldilocks zone,” where the
energy coming from a host star is intense enough to melt ice, but not so
intense that it boils water away. For planets that rotate slowly, with days
lasting more than 20 Earth days, habitability drops significantly because of
the cooler land temperatures that can result from long stretches when a
planet’s Sun isn’t overhead. For planets that turn more rapidly, the tilt of
the planet on its axis becomes important for habitability.
The study was funded under a Habitable
Worlds grant through the NASA Research Opportunities in Space and Earth
Sciences program.
~James Riordon
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