Astronomers are proposing a new definition of a planet, nearly two decades after a previous such change led to Pluto’s demotion. The new definition would add measurable criteria, including considerations of the planet’s mass — and it would still leave Pluto with its dwarf planet status. Currently, the International Astronomical Union (IAU) defines a planet … Read more
Many maps of the solar system make it look as though everything in space moves in perfect, concentric circles. Planets orbit the sun, and moons orbit the planets. So that must be the case for everything in space, right? Not quite. Orbits form all sorts of shapes. “Planets and other bodies rarely go around in … Read more
The solar system contains eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, all of which circle the sun due to its intense gravitational pull. But is this the maximum number of planets that can orbit the sun? Or is there room for more? Compared with other known planetary systems, the solar system … Read more
