Escape Velocity of Uranus
| Value | 21,300 m/s |
| Status | Conventional / typical value |
| Source | NASA NSSDC Planetary Fact Sheet, Uranus (escape velocity) |
| Categories | Astronomicalsolar-systemplanets |
| millimeter per year | 672,176,880,000,000 mm/yr |
| millimeter per hour | 76,680,000,000 mm/h |
| foot per day | 6,037,795,300 ft/d |
| inch per hour | 3,018,897,600 in/h |
| meter per day | 1,840,320,000 m/d |
| millimeter per minute | 1,278,000,000 mm/min |
| meter per hour | 76,680,000 m/h |
| inch per minute | 50,314,961 in/min |
| millimeter per second | 21,300,000 mm/s |
| foot per minute | 4,192,913.4 ft/min |
| centimeter per second | 2,130,000 cm/s |
| meter per minute | 1,278,000 m/min |
| inch per second | 838,582.68 in/s |
| kilometer per hour | 76,680 km/h |
| foot per second | 69,881.89 ft/s |
| mile per hour | 47,646.743 mph |
| knot | 41,403.888 kn |
| meter per second | 21,300 m/s |
| mach (sea level) | 62.592934 Ma |
| kilometer per second | 21.3 km/s |
| speed of light | 0.000071049152 c |
Learning zone
At 21.3 km/s, Uranus keeps everything: even hydrogen, the lightest and fastest gas, cannot reach escape speed from an atmosphere at 76 K, the coldest planetary cloud tops in the solar system. The chill is itself a puzzle — alone among the giants, Uranus radiates almost no more heat than it receives, as if its primordial interior heat were lost or locked away, possibly in the same ancient collision that knocked the planet sideways.
The escape velocity a mission cares about runs the other way. Getting to Uranus cheaply means a Jupiter gravity assist, and the windows when Jupiter stands in the right place recur only every 13–14 years — the orbital mechanics behind the urgency in the 2023 decadal survey's call for a Uranus orbiter. Voyager 2 remains the only spacecraft to have used one: its 1986 flyby borrowed Uranus's own gravity to bend onward to Neptune, completing the Grand Tour alignment that occurs once in 175 years.