planetesimals

"Clouds were forming interesting shapes in the sky. "

"The dry-stone wall used a large, flat through to support the top stones. "

"Ancient astronomers observed that seven planets – the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn – moved differently than the fixed stars. "

"The plants gradually grew taller over the summer. "

"Scientists believe that protoplanets, formed from smaller space rocks, eventually crashed together to create the planets in our solar system. "

"My science class requires us to use astronomical charts to identify constellations. "

"The gravitational pull of the Earth keeps us on the ground. "

"The attraction of a good teacher to their students is often strong. "

"When a body collides with another, then momentum is conserved."

"The teacher's lesson plan was together, covering all the key concepts logically. "

"The children collected colorful objects from the beach, like seashells and smooth stones. "

"The wet sand clumped together in my bucket when I tried to build a sandcastle. "