Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: When light passes from one medium to another, it changes speed.

Output: When light passes from one medium to another, it changes what?


Input: Consider Input: The core of a star collapses during a supernova, forming a neutron star.

Output: The core of a star collapses during what event, forming a neutron star?


Input: Consider Input: High altitude above sea level causes the alpine tundra to be so cold.


Output: What causes the alpine tundra to be so cold?