Final answer:
Planets are indeed in constant free fall towards the sun but the correct horizontal velocity ensures they stay in orbit, guided by Kepler's laws of planetary motion. This concept also relates to the weightlessness experienced by astronauts.
Step-by-step explanation:
The assertion that planets in orbit around the sun are actually ‘falling’ towards the sun and missing it due to their speed is true. Planets are in constant free fall towards the sun, but because they have the correct horizontal velocity, they keep missing it. This phenomenon is similar to how astronauts experience weightlessness in orbit; they are in free fall, but the Earth's curvature falls away from them as they move forward, creating a stable orbit. Kepler's laws of planetary motion also apply, describing how a planet's speed increases as it approaches the sun and decreases as it moves away, which explains why orbits are not perfect circles but ellipses, with the sun at one focus.