Pluto has a new moon! Using the Hubble Space Telescope, astronomers discovered the tiny object with the provisional name of S/2012 (134340) 1. “S” refers to satellite, “134340″ is Pluto’s official minor planet name and “1″ is the first new moon of Pluto discovered in 2012.
That’s all fine and good, but we’re going to call it by its nickname “P5″, the fifth moon found around the dwarf planet.
P5 is extremely faint (magnitude 27) and orbits just 58,000 miles from Pluto. Based on its faintness and the reflectivity of its surface, the moon is estimated at 6 to 15 miles across. Even to Hubble’s eye it’s only a speck of light.
Pluto probably got its moons as a result of a collision between the dwarf planet and another asteroid billions of years ago. Objects move very slowly in the outer solar system far from the sun. The collision that lofted chunks of Plutonian crust into space was gentle enough for some of the debris to be captured in orbit. Much of the remainder fell back to Pluto.
On July 14, 2015, the New Horizons spacecraft is scheduled to fly just 6,000 miles from the erstwhile planet at 32,000 mph. At that speed, even a collision with a pebble could destroy the probe. Astronomers are using the Hubble to hunt down as much “orbital debris” as possible in case the craft’s trajectory needs to be changed to avoid a potential hazard.
Pluto is the Roman god of the underworld; Charon the ferryman who sailed the souls of the dead across the River Styx; Nix the Greek goddess of darkness and night and Hydra, a many-headed serpent that guarded the underwater entrance to the underworld.
Sunspot group 1520 is still a spectacle through a small telescope equipped with a solar filter. I can’t get enough of this prolific outbreak of magnetic energy on the sun’s photosphere.
Today the group directly faces Earth AND just released a powerful X1.4 class flare at 11:53 a.m. (CDT). This and additional flares from the region in the next few days would be Earth-directed, bringing with them a good chance for auroras late this weekend and early next week. I’ll post alerts if that’s likely to happen.
There’s still more sun-related news. Returning comet 96P/Machholz showed up today in SOHO’s C3 coronagraph, a device that blocks sunlight so astronomers can study the sun’s outer atmosphere or corona. The comet will pass only 11.2 million miles from the sun when it reaches perihelion on July 14. Then in late July it will swing north of the sun into the early evening sky where observers with small telescopes might catch it shining around 8th magnitude. I’ll have more on Machholz in tomorrow’s blog.