An international team of astronomers has discovered that Neptune's south pole is much hotter than the rest of the planet, NASA's jet propulsion laboratory (JPL) reported Tuesday.

©NASA/JPL-Caltech
An international team of astronomers has discovered that Neptune's south pole is much hotter than the rest of the planet.


"The temperatures of south pole are so high that methane gas, which should be frozen out in the upper part of Neptune's atmosphere, the stratosphere, can leak out through this region," said Glenn Orton of NASA's JPL.

Orton is lead author of a paper appearing in the Sept. 18 issue of the journal Astronomy and Astrophysics.

These findings were made using the Very Large Telescope, located in Chile, operated by the European Organization for Astronomical Research in the Southern Hemisphere (known as ESO).

In the paper, Orton and his colleagues report that the temperature at Neptune's south pole is hotter than anywhere else on the planet by about 10 Celsius degrees. The average temperature on Neptune is about minus 200 Celsius degrees.

Neptune, the farthest known planet of our solar system, is located about 30 times farther away from the sun than the Earth is. Only about one thousandth of the sunlight received by our planet reaches Neptune. Yet, the small amount of sunlight Neptune does receive significantly affects the planet's atmosphere.

The astronomers found that these temperature variations are consistent with seasonal changes. A Neptunian year lasts about 165Earth years. It has been summer in the south pole of Neptune for about 40 years now, and they predict that as winter turns to summer at the north pole, an abundance of methane would leak out of a warm north pole in about 80 years.