celestial exploration: a journey through space

space solar system planets stars galaxies astronomy cosmology universe celestial bodies orbit rotation revolution gravity astrophysics planetary science stellar evolution galactic structure cosmic expansion black holes neutron pulsars nebulae star formation comets asteroids metors meteorites exploration telescopes spacecraft rockets launches orbiters landers rovers robots alien life exoplanets biosignatures astrobiology habitability terraforming interstellar travel wormholes hole singularities strings