Jupiter Magnetospheric Orbiter the orbiter was proposed for a lift-off in 2020 together with ESA's Jupiter Ganymede Orbiter (JGO) from which it would undock upon its arrival at Jupiter in 2025/2026. However, the EJSM collaboration was disbanded and NASA renamed its initiative with Europa Multiple-Flyby Mission, ESA's Jupiter Icy Moon Explorer, and Roscosmos's Laplace-P. The JMO objective was to undertake detailed "in situ" studies of the magnetosphere of Jupiter as a template for an astrophysical magnetised disk for "3-point" investigations of the Jupiter system via synergistic observations with other orbiters. The size and weight of the JMO would have been limited to carry
Jupiter usually the fourth brightest object in the sky (after the Sun, the Moon and Venus); at times Mars appears brighter than Jupiter. Depending on Jupiter's position with respect to the Earth, it can vary in visual magnitude from as bright as −2.94 at opposition down to −1.66 during conjunction with the Sun. The mean apparent magnitude is -2.20 with a standard deviation of 0.33. The angular diameter of Jupiter likewise varies from 50.1 to 29.8 arc seconds. Favorable oppositions occur when Jupiter is passing through perihelion, an event that occurs once per orbit. Earth overtakes Jupiter every 398.9 days as