Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and “Xena” (2003 UB313). When is a planet really a planet?
Astronomers at the International Astronomical Conference Union in Prague are debating this question at the moment. If these ‘three new’ planets are not accepted then that will most likely be the death knell for Pluto’s status as a planet. Dr. Nick Lomb, Sydney Observatory’s astronomer who is currently in Prague, will cast his vote on Thursday 24th August.
The proposed new factors determining if an objects is a planet include:
1. The object must orbit the sun and not a planet,
2. It must be large enough to be predominantly spherical or round
Size remians a contentious criteria as Pluto is smaller than the Earth’s Moon and the newly discovered 2003 UB313.
How would you vote?
(To find out more about our planets visit Sydney Observatory and interact with an astronomer who will show you the planets , including 2003 UB313(Xena) in the 3-D Space Theatre. Daily 2:30 and 3:30pm or as part of a night tour)