"Planetesimal" Natural Recordings by Native Speakers
A planetesimal is a small solid object in a protoplanetary disk or an asteroid belt, which plays a crucial role in the formation of planets through accretion. Planetesimals range in size from tiny dust particles to objects several kilometers in diameter. As multiple planetesimals collide and merge, they grow in size and eventually form larger bodies such as planetoids or full-fledged planets.
A large quantity of something that is transported in an aircraft, especially a large number of people or products.
There is no word "planer". However, I'm assuming you meant "planner" or "plane(r)". Planner: a person who plans or arranges things in detail. Planer: Not a commonly used word in modern English, but it could be a rare or obsolete Term, or possibly a proper noun. Plane(r): a flat surface or a machine that flies through the air, or a musical instrument played with a keyboard.
A building or a dome-shaped structure where a show of the night sky, particularly the stars, planets, and celestial objects, is projected onto the interior surface for educational and entertainment purposes.