Added 2 new A* pages:Just about a year after researchers using the Hubble Space Telescope to look for a ring system around Pluto discovered Pluto's forth moon, researchers using Hubble to check for objects that might collide with the New Horizons probe when it passes near the (dwarf) planet have discovered a fifth moon of Pluto, according to NASA. With an irregular shape that may be something from 10 to 25 km across, moon S/2012 P 1 (or more simply, "P5") has taken the record from P4 for being the smallest known moon. Here's the updated family photo:|
image by NASA; ESA; M. Showalter, SETI Institute (source)
Scientists have been surprised by the complexity of the Pluto system, and think it may be the result of a collision between Pluto and some other object out in that distant and mysterious part of our solar system known as the Kuiper belt. One thing that suggests this is the nearly circular and nicely resonant orbits of the moons; if they were captured objects rather than moons that formed around Pluto from orbiting debris, their orbits would likely be more elliptical.
Pluto's shaping up to be a pretty funny little dwarf system indeed! Its inner, largest moon, Charon, is fully half as far across as Pluto itself is (1207 vs 2306 km), while the other known moons are wee little things possibly under 100 km across (source). There's a nice diagram showing just how much Pluto and Charon dwarf the other moons (except for P5, which wasn't discovered when this diagram was made) right here (wide image).
Some rather awfully rough character design sketches from the past few days: