It's an impossible question to answer -- unless you're Neil deGrasse Tyson. Watch the famed astrophysicist take on a young boy's loaded query, and knock it out of the park.
A stretchy synthetic skin is embedded with sensors to replicate a skin-like sense of touch for prosthetics.
In a world first, a double amputee has been fitted with two prosthetic limbs -- which he can control simultaneously just by thinking.
A pooch born with deformed front legs gets to run like other dogs for the first time after getting fitted with a custom set of 3D-printed prosthetics.
A child-sized 3D-printed prosthetic hand packs in LEDs for a light-up thruster, Bluetooth, an Arduino and options for a whole bunch of cool Iron Man tech.
A man in Sweden has become the first recipient of a mind-controlled prosthetic arm that is directly interfaced with muscle, bone and nerves.
A custom 3D-printed prosthetic hand brings the "snikt" with Marvel hero Wolverine's signature colours -- and detachable claws.
Double amputee Hero has been given a pair of new "high tech" prosthetic hooves after losing his real ones to frostbite.
A determined maker without health insurance learns the ropes of 3D printing to make himself a new fingertip.
A prosthetic hand taps into nerve bundles located in the arm to allow the wearer to "feel" with the prosthetic fingers.