January 13

1610 – Galileo Galilei discovers Ganymede, 4th moon of Jupiter.
1942 – A test pilot becomes the first person to escape from a stricken aircraft with an ejection seat.
1993 – Endeavour heads for space for the third time as STS-54 launches from the Kennedy Space Center.

Fun Fact:

Some large telescopes use liquid mercury as a reflective mirror instead of glass.
The rotating liquid assumes the parabolic shape regardless of the container's shape and it costs much lower than traditional glass mirrors.