The deepest hole anyone has ever dug is only 0.2% of the way to the Earth’s center. But then….how do we know that our Earth has a solid core?!? For a long time we thought the entire inside was molten, until a scientist looked at how ripples from earthquakes – seismic waves – bounced around inside the earth. Now we know we have a solid inner core that rotates at a different rate than on the surface, and right now it's slowing down! To find out why, subscribe! #shorts #science #earth #core #inside #earthquake