The top picture shows Neptune as our eyes would see it. The bottom picture is infrared "light", which shows heat. The bright spot at the bottom of the IR image shows that Neptune's South Pole is the warmest place on the planet!
Click on image for full size
Images courtesy of NASA/JPL (visible light) and VLT/ESO/NASA/JPL/Paris Observatory (infrared).
The Poles of Neptune and Its Moons
The South Pole of the planet Neptune is a bit strange. Triton, Neptune's largest moon, also has interesting features at its poles.
Neptune is tilted on its axis by about 28°. That isn't so strange... Earth is tilted, too, by a similar amount of 23°. That means Neptune's poles take turns being in sunlight or in shadow. So Neptune has seasons, like Earth. However, Neptune takes roughly 164 years to orbit the Sun once. That means each season on Neptune lasts more than 40 Earth years! It has been summertime in Neptune's Southern Hemisphere for the last few decades. Sunlight has been warming Neptune's South Pole for many years. The South Pole of Neptune is the warmest place on the planet!
Earth is pretty much a solid ball of rock. Neptune is not; it is made up of gases and ice. Different parts of Neptune spin at different speeds. Places near its equator go around every 18 hours, but places near the poles spin around every 12 hours. Because of this, between the poles and the equator there are some very strong winds. At 70° south latitude they blow at speeds of 1,080 km/hr (671 mph)! Some of the chemicals in Neptune's atmosphere are different at the poles, too. There is much less methane, ethane and acetylene at the poles than at the equator.
Neptune's magnetic field is tilted too. It isn't lined up with Neptune's spin axis. Earth's magnetic field is tilted, too, but only by a small amount... about 11°. Neptune's magnetic field is tilted a lot more... about 47°. If Earth's magnetic field was tilted that much, the North Magnetic Pole would be somewhere south of Paris.
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