The exploration of the Pluto system by the New Horizons spacecraft

Pluto’s largest moon Charon are revealed in this image from New Horizons’ Long Range Reconnaissance Imager (LORRI), taken late on July 13, 2015 from a distance of 289,000 miles (466,000 kilometers). NASA-JHUAPL-SWRI

The exploration of the Pluto system by the New Horizons spacecraft has also revealed surface features on Pluto's largest moon, Charon, showing what look like impact craters and chasms splitting the landscape. One of the most obvious chasms splits the southern hemisphere, and appears to be much longer and deeper than the Grand Canyon in Arizona. This was never detected before the New Horizons spacecraft got close enough to image things in great detail.

Before this image, Charon looked like nothing more than a featureless gray ball.

There's also at least one major crater on Charon, which is close to the moon's south pole. It's close to a hundred kilometers (60 miles) across, and it is surrounded by bright rays of material splashed out during the impact.

Mission scientists think this very obvious crater is a relatively recent one, in geologic time, perhaps less than a billion years old. It's "floor" is relatively dark, and there's a suggestion that when the impactor smacked into Charon, it dug out (exposed) a different sort of icy surface material than is on the upper surface. Planetary scientists have also suggested that there are some other differences between the ices in the crater or on the surface. Maybe the ices remelted and refroze into smoother ice or larger chunks of ice after the impact.

What smacked into it? The most likely candidate is another Kuiper Belt Object orbiting out in this frigid zone of the solar system.

The New Horizons mission traveled more than 10 years to get to Pluto, moving at a speed of 49,600 kilometers per hour (30,800 miles per hour).

It has a collection of seven science instruments busily gathering data. It is on a trajectory out of the solar system and will pass by at least one more outer solar system object along its path. This is the only probe to visit this part of the solar system for the foreseeable future.

Pluto and Charon are sometimes thought of as a "double planet", although that is not an official designation. With the discoveries made by New Horizons, many ideas about the outer solar system and, in particular, the Kuiper Belt — home to comets as well as other small worlds — will have to change. Among them is the idea of Pluto as a dwarf planet, as well as the perception that there is little to explore in this distant part of the solar system. It turns out this world is one of many such "dwarf planets" and the Kuiper Belt is a treasury of places to study.

The Pluto system has five moons, and lies so far away from Earth that it takes more than four hours to send a one-way message there. As New Horizons moves farther away, round-trip conversations with it will take longer, and longer. Eventually the spacecraft will leave the solar system on a one-way trip. It carries onboard the ashes of Pluto's discoverer, astronomer Clyde Tombaugh, as well as the names of several hundred thousand people on a storage disk. It will communicate with Earth until its fuel runs out and can no longer send signals to the home planet.

The cameras and instruments onboard New Horizons comprise cameras to take high-resolution images, as well as spectrometers, which are instruments designed to study light being reflected off the surfaces of the worlds. Other sensors include a dust counter, built by college students at the University of Colorado, as well as detectors for energetic particles such as cosmic rays.