NASA's planet-hunting TESS mission has found its first Earth-size exoplanet in a star system only 53 light-years from Earth. (CNN) - Space is not a friendly environment, even for the stars, planets and galaxies born in its cold, violent reaches. When applied to our own solar system, these theories point to the suggestion of a rocky planet closer to our sun than Mercury. Did the planet just not form or was it kicked out of the solar system? Pondering the idea, Flock said it's interesting to think "not only that our Solar System was baby-proof -- it is possible that the baby thus protected has since 'flown the nest.'"

This diagram shows the layout of the GJ 357 system. Planet d (at left) orbits within the stars so-called habitable zone, the orbital region where liquid water can exist on a rocky planets surface. Multiple exoplanets -- planets orbiting stars outside our solar system -- were discovered orbiting an M-dwarf star, called GJ 357 in the Hydra constellation. The first exoplanet discovered around the star was GJ 357 b. "We describe GJ 357 b as a 'hot Earth,'" said Enric Pall, study co-author and astrophysicist at the Institute of Astrophysics of the Canary Islands.