sentence: Many extrasolar planets are known to move in highly elliptical orbits.
sentences_before: No information is available about the shape of the planet's orbit.
sentences_after: We only know that the semi-major axis of its orbit is within its host star's habitable zone. If Kepler-22b has a highly elongated orbit it may well only spend a small fraction of its time within this habitable zone, which would cause extreme temperature differences on the planet and make it inhospitable.
concept_name: extrasolar planet
headings: Kepler-22b Orbit
categories: Exoplanets