by Jonathan O'Callaghan
Those fantastic high-resolution images of Pluto you’ve been seeing lately have mostly just shown one side of the dwarf planet, owing to the brief flyby made by the New Horizons probe. However, in the run up to the flyby, New Horizons snapped images of the entirety of Pluto – and its largest moon Charon.
As Pluto rotates once every 6.4 Earth days, the Long Range Reconnaissance Imager (LORRI) and the Ralph/Multispectral Visible Imaging Camera on New Horizons were able to snap images of the rotation of the world. Starting at 8 million kilometers (5 million miles) out on July 7, the images run up to a distance of 645,000 kilometers (400,000 miles) on July 13, a day before the closest approach.
While one side of Pluto – with the heart-shaped region informally known as Tombaugh Regio – was snapped in higher resolution, the other hemisphere will not be seen in greater detail for the foreseeable future. New Horizons snapped no better images of it, and there is no other mission to Pluto planned.
A separate mosaic reveals a full day on Pluto’s largest moon Charon, which again only had one hemisphere in full view of New Horizons as it sped past. It also completes a rotation every 6.4 days, meaning it is tidally locked to Pluto – so it always appears in the same place in the sky from the dwarf planet.
Image credit: A full day on Charon. NASA/JHUAPL/SwRI
Unlike Pluto, the two hemispheres of Charon look fairly similar, with craters and ridges strewn across its surface. Both worlds are continuing to produce fascinating science, such as the recent discovery of volcanoes on Pluto.
New Horizons, meanwhile, is continuing to return data to Earth but is also on its way to an encounter with a Kuiper Belt Object (KBO) far beyond the orbit of Pluto.
