News broke today that some circumstantial evidence suggests the existence of a new planet in our solar system. Unlike poor Pluto which lost its official planet status, this planet is estimated to mass 5 to 10 times Earth, which would make it indisputably a planet.
To be clear, the planet has not yet actually been discovered. Instead, its existence has been inferred by noting that a number of Kuiper belt objects that *have* been observed appear to be gravitationally perturbed by a single object that fits the Planet IX description. If it is eventually found, we won;t be sending probes to it anytime soon… it’s estimated orbital semimajor axis averages 600 AUs; it might get as close to the sun as 200 AU. Neptune is a mere 30 AU from the sun. It is thought to be an ice giant… a large rocky core that *could* have turned into a gas giant, but is too far out to have gathered much gas during the initial formation of the solar system, and what gas it does have is frozen as ice onto the surface. Due to its extreme distance (600 AU), it’s thought to probably look 600 times dimmer than Pluto as seen through a telescope. Sunlight should be about 0.0025 times as bright as it is on Pluto, or 0.0000028 times as bright as on Earth… one part in 360,000. In other words: kinda dark. So if you’re planning on sending a probe, basically the day side of the planet would be like trying to photograph the night side of the moon. If we duplicated the New Horizons mission (interesting note: new Horizons launched ten years and one day ago) to this world, it would take at least 190 years for the probe to get there.