Answer is Retrograde motion
Most of the time planet moves in expected path near the ecliptic which is east to west. Some times each planet turns around and moves to the east for a period of time, then it turns around to head in west direction again making a loop or zig-zag against the star background. This is called retrograde motion. Thus retrograde motion is the change of direction of the planets in loop.
20 meters walk south is the <u>short leg</u>. The long leg is 30 meters walk east. Distance from 30 meters east to starting point is a hypotenuse.
Rock layers in order is basically natures calendar.
The highest layer is the newest formed layer
While the deepest layer was the oldest and probably has been there from some time
And everything in between goes accordingly
So putting rocks in order by age helps scientists better understand what was there before what and how the rocks changed over time.
Hope this helps!
Brailiest is always appreciated if you feel its deserved! :)
