the star from the perspective of Earth, making it difficult to study their properties. GJ 876 is a candidate parent system for the ʻOumuamua object. The trajectory of this interstellar object took it near the star about 820,000 years ago with a velocity of 5 km/s, after which it has been perturbed by six other stars. Orbital arrangement Gliese 876 has a notable orbital arrangement. It is the first planetary system around a normal star to have mutual inclination between planets measured without transits (previously the mutual inclination of the planets orbiting the pulsar PSR B1257+12 had been determined by measuring their gravitational interactions). Later measurements reduced the value of the mutual inclination, and in the latest four-planet models the incorporation mutual inclinations does not result in significant improvements relative to coplanar solutions. The system has the second known example of a Laplace resonance with a 1:2:4 resonance of its planets. The first known example was Jupiter's closest Galilean moons - Ganymede, Europa and Io. Numerical integration indicates that the coplanar, four-planet system is stable for at least another billion years. This planetary system comes close to a triple conjunction between the three outer planets once per orbit of the outermost planet. Planets The outermost three of the known planets likely formed further away from the star, and migrated inward. Gliese 876 d Gliese 876 d, discovered in 2005, is the innermost known planet. With an estimated mass 7.55 times that of the Earth, it is possible that it is a dense terrestrial planet. Gliese 876 c Gliese 876 c, discovered in 2001, is a 0.84 Jupiter-mass giant planet. It is in a 1:2 orbital resonance with the planet b, taking 30.097 days to orbit the star. The planet orbits within the habitable zone. Its temperature makes it more likely to be a Class III planet in the Sudarsky extrasolar planet classification. The presence of surface liquid water is possible on sufficiently massive satellites should they exist. Gliese 876 b Gliese 876 b, discovered in 1998, is around twice the mass of Jupiter and revolves around its star in an orbit taking 61.106 days to complete, at a distance of only 0.219 AU, less than the distance from the Sun to Mercury. Its temperature makes it more likely to be a Class II or Class III planet in the Sudarsky model. The presence of surface liquid water is possible on