solar system – n. our sun and the planets that move around it

journal – n. a magazine that reports on things of special interest to a particular group of people

alien – adj. from somewhere other than the planet Earth

tidal – adj. of or relating to the regular upward and downward movement of the level of the ocean that is caused by the pull of the Sun and the Moon on the Earth

comet – n. an object in outer space that develops a long, bright tail when it passes near the sun

asteroid – n. any one of thousands of small planets that circle around the sun

disrupte(d) – v. to cause (something) to be unable to continue in the normal way

mutual – adj. shared between two or more people or groups

hypothesize(d) – v. to suggest an idea or theory