SCIENCE LAB SPECIAL : HIDDEN OCEANS

 

Looking for water on Neptune or Uranus ? You have to dig deep?

We might finally understand what's going on inside Uranus and Neptune, and the answer is pretty surprising  : 

 They may each contain an ocean of water. The idea about the two planets - known as ice giants because of the freezing conditions in which they formed - was put forward by Burkhard Militzer, a planetary scientist from the University of California, Berkeley, and was published  in the Proceedings of the National Academy of Sciences. It could explain the strange magnetic fields of both worlds.

Earth's magnetic field is generated in its core, producing a clear north and south pole known as a dipole that roughly aligns with the axis of the planet.

''It's like there's a big, giant bar magnet inside the planet,'' said Heidi Hammel, an astronomer and planetary scientist at the Association of Universities for Research in Astronomy. ''That's true for Jupiter, Saturn, Earth, and some of the moons of Jupiter as well.''

When NASA's Voyager 2 spacecraft flew past Uranus in 1986, however, ''the magnetic field was hugely tilted and offset from the center of the planet,'' Dr. Hammel said.

At first, scientists thought that the disordered field could be explained by a giant impact that's thought to have happened early in Uranus's existence. But then the spacecraft flew past Neptune three years later and found that its magnetic field was also significantly tilted.

The Militzer's proposal, which was based on simulating the motion of 500 atoms to model the interiors of the two ice giants, suggests that there is a layer of water about 5,000 miles [ 8,000 kilomters ] thick inside the two planets, sitting beneath their outer atmospheres.

'' We think it's an ocean,'' Dr. Militzer said. '' There's hydrogen mixed in with it, and it has a high conductivity that's important for the magnetic field.'' [ Jonathan O' Callaghan ]