VOA慢速英语:“外星小行星”可能是太阳系中最古老的天体

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

solar system – n. a star other than our sun and the planets that move around it

swirl(ing) – v. to move in circles or to cause something to move in circles

alien – adj. from somewhere other than the planet Earth

interact(ed) – v. to come together and have an effect on each other

fit(ting) – v. to be the right size and shape for someone or something

cluster – n. a group of things or people that are close together

proximity – n. the state of being near

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

collide(d) – v. to hit something or each other with strong force