1Two things you need to know
A "year" is one loop — and the Sun's pull is a leash
You only need two ideas. Watch each one:
A year = one full loop
Every planet circles the Sun. One trip all the way around and back to the start is exactly one year. Finish the loop, you're a year older.
The Sun's pull is a leash
The Sun tugs on every planet. Up close the leash is tight and strong. Far out the leash goes weak and floppy — the farther you are, the gentler the tug.
2Two runners, two lanes
The inside lane vs the outside lane
Think of a track. A close planet runs the inside lane; a far planet runs the outside lane. One thing is obvious — but keep an eye out for a second one:
The close planet
A short loop, tight against the Sun. The strong pull keeps it whipping around.
The far planet
A much bigger loop, way out in the cold. What about its speed? That's the part to watch.
3Your turn — move a planet
Slide one planet in and out and watch its year change
Drag the planet from close to the Sun all the way out to the cold. Watch its loop grow — and watch the year counter climb each time it finishes a lap.
4Now race them
Two planets, one start line — does the far one move at the same speed? 🏁
Forget moving one planet. Now we lock a close planet and a far planet in place and let them go at the very same instant. Guess first — then release them and count the birthdays.
Guess before you release them
A far-out planet has a longer path to travel. Does it move along that path at the same speed as a close one — or slower?