1 00:00:01,000 --> 00:00:06,000 In the outer reaches of the Solar System, nearly six billion kilometres away, 2 00:00:06,000 --> 00:00:11,000 the dwarf planet Pluto slowly orbits the Sun. 3 00:00:11,000 --> 00:00:17,000 Before NASA’s New Horizons probe flew past the icy world in July 2015, 4 00:00:17,000 --> 00:00:25,000 almost all the information we had about this distant object came from observations made by Hubble. 5 00:00:44,000 --> 00:00:49,000 Discovered in 1930 by the American astronomer Clyde Tombaugh, 6 00:00:49,000 --> 00:00:54,000 Pluto was originally classified as the ninth planet of the Solar System. 7 00:00:56,000 --> 00:01:03,000 However, as more and more objects of a similar size, mass, and composition were discovered, 8 00:01:03,000 --> 00:01:08,000 astronomers started to question whether it was truly a planet. 9 00:01:13,000 --> 00:01:17,000 In 2006, they decided it wasn’t. 10 00:01:17,000 --> 00:01:23,000 Pluto was reassigned to the newly defined category of dwarf planet. 11 00:01:30,000 --> 00:01:37,000 Until July 2015, when NASA’s New Horizons space probe reached Pluto after nine years of flight, 12 00:01:37,000 --> 00:01:42,000 almost all the information that we had about Pluto came from Hubble. 13 00:01:47,000 --> 00:01:54,000 Pluto’s largest moon, Charon, was discovered by the United States Naval Observatory in the USA 14 00:01:54,000 --> 00:01:58,000 before Hubble was launched in 1990. 15 00:01:58,000 --> 00:02:06,000 After launch, Hubble turned its gaze to this small system, to see what more it could find out. 16 00:02:09,000 --> 00:02:14,000 The space telescope was able to discover four additional moons around Pluto, 17 00:02:14,000 --> 00:02:19,000 due to its advantageous position outside of Earth’s atmosphere. 18 00:02:20,000 --> 00:02:27,000 Hubble observations from 2006 uncovered the small moons Nix and Hydra, 19 00:02:27,000 --> 00:02:31,000 both less than 60 kilometres in diameter. 20 00:02:33,000 --> 00:02:40,000 In 2011 and 2012 two additional moons were found in Hubble data. 21 00:02:40,000 --> 00:02:47,000 They were named Kerberos and Styx, fitting the names of two of the other moons and Pluto itself 22 00:02:47,000 --> 00:02:52,000 in being creatures and places of the mythological greek underworld. 23 00:02:54,000 --> 00:03:01,000 Hubble images taken over a period of time allowed astronomers to estimate the size and brightness 24 00:03:01,000 --> 00:03:08,000 of the moons, and showed that both Nix and Hydra are chaotically tumbling as they orbit. 25 00:03:09,000 --> 00:03:14,000 Astronomers think that the same would be true for Kerberos and Styx. 26 00:03:18,000 --> 00:03:24,000 Over the years, Hubble’s sharp vision has allowed some features to be seen on Pluto. 27 00:03:24,000 --> 00:03:27,000 These span several hundred kilometres, 28 00:03:27,000 --> 00:03:33,000 and the planet’s polar regions as well as some large bright spots are visible. 29 00:03:34,000 --> 00:03:40,000 These remained the most detailed maps of Pluto until the New Horizons flyby. 30 00:03:45,000 --> 00:03:50,000 Hubble's high-resolution images can’t compete with pictures taken from probes 31 00:03:50,000 --> 00:03:53,000 that pass close to the planets of the Solar System. 32 00:03:54,000 --> 00:03:59,000 However, Hubble has the advantage of being able to carry out long-term monitoring, 33 00:03:59,000 --> 00:04:03,000 returning to look at these objects periodically. 34 00:04:05,000 --> 00:04:11,000 This is crucial for the study of planetary atmospheres and geology. 35 00:04:14,000 --> 00:04:20,000 In the coming years, astronomers plan to use the infrared vision of Hubble’s successor 36 00:04:20,000 --> 00:04:27,000 the NASA/ESA/CSA James Webb Space Telescope, for future observations of Pluto. 37 00:04:27,000 --> 00:04:35,000 This telescope, planned for launch in 2018, will be able to study the surface chemistry of Pluto, 38 00:04:35,000 --> 00:04:40,000 its moons, and many other bodies that lie in the distant region around Pluto, 39 00:04:40,000 --> 00:04:47,000 hopefully resolving many of the mysteries lurking in the outer reaches of the Solar System. 40 00:05:06,000 --> 00:05:10,000 Transcribed by ESA/Hubble, Translated by ---