New Horizons is approaching Pluto! Let's see its timeline of approaches and discoveries:

  • July12th UTC 11 AM:A ring, designed R/2015(134 340)Pluto 1, is discovered.
  • July12th UTC 1 PM:The new data suggests the mass and diameter of Pluto is (1.3157±0.0012)×1022 kg and 2386.45±0.97km.
  • july13thUTC 2AM:A photograph suggests a ring arc around Styx.(Ring arcs are not necessarily rings. These are the so-called proto-rings, which are not that disrupted by the host planet/space object's gravity yet(in this case, Pluto). The ring arc is always formed by an big asteroid impact on a moon that throws(more like blast) materials outward from the moon.) This is the first such system around a minor planet.
  • July 13th UTC 3AM: a moon is discovered and named S/2015(134 340)Pluto I. It is the first such moon without a clear resonance with Charon. It might be 3:10, though. The calculation puts its diameter at around 1.5km.
  • July 13th UTC 5AM: New Horizons finds a possible moon candidate around Charon on its image of discovery of the ring.
  • July 13th UTC 6AM: the moon is confirmed. It is called S/2015(134 340I)Charon 1.
  • July 13th UTC 10AM: the atomsphere of Pluto is measured. It is mostly nitrogen, with 12% methane and some others. The escape rate is surprisingly high: about 0.26% per year.(main missions of Pluto)
  • July 13th UTC 1PM: the chemical composition of Charon and Pluto is mapped.
  • July 13th UTC 6PM: now, most of New Horizon's main and secondary objectives are completed. New Horizons also send a new map of Pluto, which didn't have lot's of craters.
  • July 13th UTC 8PM: New horizons saw a new asteroid flying toward Pluto. It is expected to collide with Charon, which will give us better learning for Charon---since it is still mostly unknown.
  • July 14th UTC 9PM: The new estimates for Charon's mass put it 11% more than pervious estimates.
  • July 14th UTC 11PM: Silver Solicate is found in Charon's atomsphere, which is the first to be found.
  • July 14th UTC 11PM: A tiny TNO smashes into New Horizons, which damages its imaging engine. The mission ends.