WEBVTT FILE 1 00:00:46.450 --> 00:00:49.090 So Mercury is special not just because it's the closest planet 2 00:00:49.100 --> 00:00:52.490 to the Sun but also because the distance it is 3 00:00:52.500 --> 00:00:55.840 from the Sun varies more than any other planet in our solar system. 4 00:00:55.890 --> 00:00:59.980 Mercury actually has a very oval-shaped orbit compared to the rest. 5 00:01:00.800 --> 00:01:04.209 Mercury is a natural laboratory for running experiments. 6 00:01:04.300 --> 00:01:08.200 We can observe the planet's surroundings as it gets closer and farther away from the Sun 7 00:01:08.270 --> 00:01:09.590 and see what changes. 8 00:01:38.730 --> 00:01:42.440 When solar wind particles bounce off this magnetospheric boundary, 9 00:01:42.500 --> 00:01:45.180 they generate low-frequency waves. 10 00:01:45.240 --> 00:01:49.330 They're like ripples traveling upstream in the solar wind. 11 00:02:11.090 --> 00:02:14.010 Farther from the Sun, the Sun's magnetic field is weaker. 12 00:02:14.180 --> 00:02:18.130 We found that this is the key parameter that allows more waves to be generated. 13 00:02:55.300 --> 00:02:58.290 This is something we could only have measured with Mercury, 14 00:02:58.300 --> 00:03:00.620 thanks to how close it is to the Sun 15 00:03:00.700 --> 00:03:03.190 and the shape of its orbit.