On Dec. 21, at 8:49:48 a.m. PST (11:49:48 a.m. EST) NASA’s Juno spacecraft will be 3,140 miles (5,053 kilometers) above Jupiter’s cloud tops and hurtling by at a healthy clip of 128,802 mph (207,287 kilometers per hour). This will be the 16th science pass of the gas giant and will mark the solar-powered spacecraft’s halfway point in data collection during its prime mission.