After nine years of waiting, the appointment with Pluto it's finally here. Today, at 13.39 Italian time, the New Horizons probe of NASA, started in 2006, will arrive at the minimum distance from the dwarf planet (12.500 kilometers). It will zip around at around 50 kilometers per hour, collecting images and data on the surface and atmosphere. Meanwhile, a swarm of charged particles released by one of the last solar eruptions will arrive on the planet.
One of the first mysteries that the probe will have to investigate is a brilliant heart-shaped structure and four large dark spots, each as large as the US state of Missouri, and placed at the same distance from each other. The features run along the equator and could be plateaus or plains, or changes in brightness over a completely smooth surface. It will be up to New Horizons to verify that. After the close passage to Pluto, the probe will also approach the moon Charon, with which the planet forms a binary system.
When the mission New Horizons had begun, in January 2006, his goal was the ninth planet of the Solar System. Such was in fact considered Pluto. The downgrading to dwarf planet was decided a few months later, on August 24, by the International Astronomical Union (Iau), in a news story that had gone around the world.
