1 00:00:00,000 --> 00:00:09,000 Researchers using the NASA/ESA Hubble Space Telescope recently took advantage of a rare opportunity to record Saturn when its rings are edge-on, 2 00:00:09,000 --> 00:00:14,000 resulting in a unique movie featuring both of the giant planet’s poles. 3 00:00:14,000 --> 00:00:17,000 Saturn is only in this position every 15 years or so 4 00:00:17,000 --> 00:00:24,000 and this favourable orientation has allowed a sustained study of the two beautiful and dynamic aurorae, 5 00:00:24,000 --> 00:00:27,000 Saturn’s own northern and southern lights. 6 00:00:45,000 --> 00:00:47,000 This is the Hubblecast! 7 00:00:47,000 --> 00:00:50,000 News and images from the NASA/ESA Hubble Space Telescope. 8 00:00:50,000 --> 00:00:56,000 Travelling through time and space with our host Dr. J, a.k.a. Dr. Joe Lisker. 9 00:00:57,000 --> 00:00:59,000 Hello and welcome to the Hubblecast. 10 00:00:59,000 --> 00:01:07,000 It takes Saturn nearly 30 years to orbit our Sun, so chances to image both poles simultanously are few and far between. 11 00:01:08,000 --> 00:01:11,000 Hubble has been snapping pictures of Saturn’s aurora since 1990, 12 00:01:11,000 --> 00:01:20,000 but 2009 brought the rare opportunity for Hubble to image Saturn with its rings edge-on and both of its poles visible, 13 00:01:20,000 --> 00:01:25,000 As Saturn was approaching its equinox, both poles were equally illuminated by the Sun, 14 00:01:25,000 --> 00:01:29,000 allowing for spectacular shots of its active aurorae. 15 00:01:29,000 --> 00:01:37,000 An enormous and grand ringed planet, Saturn is certainly one of the most intriguing bodies orbiting the Sun. 16 00:01:37,000 --> 00:01:43,000 Hubble has now taken a fresh look at the fluttering aurorae that light up both of Saturn’s poles. 17 00:01:43,000 --> 00:01:51,000 These recent observations go well beyond just a still image and have allowed researchers to monitor the behaviour of both Saturn’s poles 18 00:01:51,000 --> 00:01:55,000 in the same shot over a sustained period of time. 19 00:01:55,000 --> 00:02:01,000 The movie they created from the data collected over several days during January and March 2009, 20 00:02:01,000 --> 00:02:06,000 has aided astronomers studying both Saturn’s northern and southern aurorae. 21 00:02:06,000 --> 00:02:15,000 Given the rarity of such an event, this new footage will likely be the last and best equinox movie that Hubble captures of our planetary neighbour. 22 00:02:17,000 --> 00:02:21,000 Despite its remoteness, the Sun is still Saturn’s parent star 23 00:02:21,000 --> 00:02:25,000 and, as we all know, a parent’s influence is far reaching. 24 00:02:25,000 --> 00:02:33,000 The Sun constantly emits particles, called the solar wind, that reaches all the planets of the Solar System, inclduing Saturn. 25 00:02:33,000 --> 00:02:40,000 When this stream of electrically charged particles gets close to a planet with a magnetic field, like Saturn or the Earth, 26 00:02:40,000 --> 00:02:44,000 the field traps the particles, bouncing them back and forth between the poles. 27 00:02:46,000 --> 00:02:49,000 A natural consequence of the shape of the planet’s magnetic field, 28 00:02:49,000 --> 00:02:54,000 a series of invisible traffic lanes exist between the two poles 29 00:02:54,000 --> 00:03:00,000 along which the electrically charged particles are confined as they oscillate between the poles. 30 00:03:02,000 --> 00:03:07,000 The magnetic field is stronger at the poles and the particles tend to concentrate there, 31 00:03:07,000 --> 00:03:12,000 where they interact with atoms in the upper layers of the atmosphere, creating aurorae, 32 00:03:12,000 --> 00:03:19,000 the familiar glow that the inhabitants of the Earth’s polar regions know as the northern and southern lights. 33 00:03:21,000 --> 00:03:27,000 At first glance the light show of Saturn’s aurorae appears to be symmetric with respect to the the two poles. 34 00:03:27,000 --> 00:03:30,000 However, analysing the new data in greater detail, 35 00:03:30,000 --> 00:03:35,000 astronomers have discovered some subtle differences between the northern and southern aurorae, 36 00:03:35,000 --> 00:03:40,000 and this reveals important information about Saturn's magnetic field. 37 00:03:41,000 --> 00:03:46,000 The northern auroral oval is slightly smaller and more intense than the southern one, 38 00:03:46,000 --> 00:03:51,000 implying that Saturn’s magnetic field is not equally distributed across the planet; 39 00:03:51,000 --> 00:03:55,000 it is slightly uneven and stronger in the north than the south. 40 00:03:55,000 --> 00:04:01,000 As a result, the electrically charged particles in the north are accelerated to higher energies 41 00:04:01,000 --> 00:04:04,000 as they are fired toward the atmosphere than those in the south. 42 00:04:04,000 --> 00:04:13,000 This confirms a previous result obtained by the space probe Cassini, in orbit around the ringed planet since 2004. 43 00:04:16,000 --> 00:04:21,000 These dramatic light shows observed by Hubble on Saturn are not only charming features, 44 00:04:21,000 --> 00:04:26,000 but they actually teach us something about the conditions on one of our magnificent planetary neighbours. 45 00:04:27,000 --> 00:04:29,000 This is Dr.J signing off for the Hubblecast. 46 00:04:29,000 --> 00:04:33,000 Once again, nature has surprised us beyond our wildest imagination.