Moons of our Solar System
Moons of our Solar System

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Moons of our Solar System

1.10 New Horizons Pluto–Charon flyby

In July 2015 the New Horizons mission flew close past Pluto and Charon – its destination after almost a decade in flight. New Horizons explored the Pluto–Charon system and provided more detail than ever seen before, though it did not find any new moons.

When it was at Pluto, the radio signal that it used to send its data back to Earth took about 4.5 hours to reach us, travelling at the speed of light. New Horizons passed close to Jupiter en route, sending back pictures of Io’s erupting volcanoes.

This NASA video was released in 2011, before Pluto’s 4th and 5th moons, now named Nix and Hydra, had been discovered. When the narrator says that New Horizons ‘still has four more years of travel to go’, he is of course out of date. Also, New Horizons did not stop when it reached Pluto. It flew close past a Kuiper Belt object, then known as 2014 MU69 (but subsequently named Arrokoth) on 1 January 2019. Observations of this passing in front of a star [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] as observed from Patagonia in July 2017 suggested that it either has an elongated/dumbell shape or else is a double object (a primary and a nearby moon!) were vindicated when the close up images by New Horizons revealed it to indeed be a contact binary - so no moon to add to the list!

Download this video clip.Video player: moons_1_vid062.mp4
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Paying a visit to Pluto-- presented by Science at NASA. At this very moment, one of the fastest spacecraft ever launched, NASA’s New Horizons, is hurtling through the void at nearly one million miles per day. Launched in 2006, it has been in flight longer than some missions last and still has four more years of travel to go.
New Horizons is headed for the lonely world of Pluto on the outer edge of the Solar System. Although astronomers now call Pluto a dwarf planet, it’s actually a large place-- about 5,000 miles around at the equator, says Alan Stern, principal investigator for the mission. And it’s never been explored.
Indeed, no spacecraft has ever visited Pluto or any dwarf planet in the outer Solar System. "This is a whole new class of world, says Stern. "To understand the Solar System, we need to understand worlds like Pluto".
Pluto is a resident of the Kuiper Belt, a vast region beyond the orbit of Neptune. Stern believes the Kuiper Belt contains a thousand dwarf planets or more, a whole zoo of them. Dwarf planets are, in fact, the most numerous class of planets in the Solar System and probably in the whole universe.
Pluto is a world of mysteries. For one thing, Stern wonders, what are the molasses-colored patches on Pluto’s surface, seen by the Hubble Space Telescope? Some scientists think that they could be deposits of primordial organic matter. New Horizon’s spectrometers will help us identify the kinds of organic molecules on Pluto. We expect to find something pretty interesting."
Hubble recently contributed more intrigue by spotting a new moon circling Pluto, bringing the total to four. Composite Hubble images of Pluto now resemble a miniature planetary system. New Horizons will hunt for even more moons as it approaches the dwarf planet.
To aid in the investigations, New Horizons is carrying one of the largest and highest resolution interplanetary telescopes ever flown. It’s called LORRI, short for long range reconnaissance imager. At closest approach to Pluto, LORRI can resolve details almost as well as a spy camera. The view will be incredible.
If we flew this instrument over Earth at the same altitude as we plan to fly over Pluto, we would see individual buildings and their shapes. What will we see on Pluto? Some researchers predict icy geysers, like the ones on Neptune’s moon Triton. Some say we could see those surface deposits of organic material.
Stern says simply, "There could be all kinds of surprises. It’s a first exploration of a new kind of planet". New Horizons is scheduled to reach Pluto in 2015. For mission updates, please visit
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