NASA's Juno spacecraft will come within 1,038 kilometres of Jupiter's moon Ganymede's surface tonight at (11:05pm PST).

This would be the closest a spacecraft has come to it since Galileo spacecraft in May 2000.  

From JunoCam's viewpoint, Ganymede will go from being a point of light to a viewable disk then back to a point of light in about 25 minutes.