Subaru also obtained spectal signatures for the two bodies that clearly reveal a very different make up for the two distant and highly eccentric bodies that are suspected by many as been super Kuiper objects.

Initial analysis of the data confirms that the surface composition for Pluto is one of frozen nitrogen, methane, carbon monoxide and newly discovered ethane "ice" (all at a temperature colder than - 346 F or -210 C). Whereas, Charon appears mostly covered in the more familiar water ice also at an extremely cold temperatures.

The detection of ethane is reagrded at particularly significant, as this material may be a remnant of the original interstellar gas cloud that collapsed to form our solar system 4.5 billion years ago, preserved over the eons by the extreme cold that exists out at the distance of Pluto's orbit.

Pluto was discovered in 1930 and is the furthest known planet in our solar system, taking 249 years to go once around the Sun. It travels in a very elongated orbit which takes it from 30 AU ("AU" = "Astronomical Unit", the distance between the Earth and the Sun = 150,000,000 km or 93,000,000 miles) to as far away as 50 AU from the Sun. It has a diameter of 2,274 km (1413 miles).

In 1978, Pluto was found to have a companion in orbit about it, the satellite Charon (pronounced "KAIR-on"). With a diameter of 1,172 km (728 miles), Charon is about half the size of Pluto which is unusually large, relatively speaking, for a satellite.

It may be more appropriate to regard the system as a binary planet rather than as a planet/satellite pair - similar to Earth and the moon. At an average separation of 19,640 km (12,200 miles or just eight Pluto diameters), Charon orbits Pluto in 6.387 days.

Charon travels in a synchronous orbit always keeping the same face pointed towards Pluto, just as the Moon does with respect to the Earth. But Pluto is unique among the planets in that it rotates at exactly the same speed that its companion orbits, always keeping the same face pointed towards Charon.

On June 9th, 1999, Pluto was 5.865 billion km (3.645 billion miles) from the Earth. At this distance, Pluto and Charon had apparent diameters of 0.08 and 0.04 arcseconds, respectively.

Although these CISCO observations are among the best ever taken from the ground (with a resolution of about 0.35 arcseconds), they are not sharp enough to show the true disks of either Pluto or Charon.

In the near future, Subaru will begin using its Adaptive Optics (AO) unit with a potential maximum resolution of 0.06 arcseconds (equivalent to being able to read newspaper headlines twenty-five kilometers or fifteen miles away). This is sufficient to begin resolving Pluto's surface features directly.

Way out there at TerraDaily