Planetary magnetic fields- The summary (part 2)

How they can drive dynamos

We know that all information of planetary magnetic fields based on indirect measurements which are mostly obtained from the space missions. We also make Earth’s dynamo process as reference to understand other planet magnetic fields, although for the Earth itself there is no certain theory how it can generate a dynamo at least 3.5 Ga (Stevenson, 2003).

Can we predict the earthquake?

Findings could lead to earthquake prediction

New instruments detect small changes in rocks along the San Andreas fault up to 101/2 hours before a temblor. But more research is needed.

By Thomas H. Maugh II, Los Angeles Times Staff Writer
July 12, 2008

U.S. researchers said they were able to measure small changes in the density of fractures along the San Andreas fault as much as 10 1/2 hours before an earthquake, a step toward the long-sought goal of predicting potentially devastating quakes.

The team has so far monitored only two events over a two-month period, so a great deal more work will be necessary before their findings can be verified and understood. But the results suggest for the first time that it may be possible to forecast quakes hours before they occur — giving residents time to prepare or, if necessary, evacuate.

Planetary magnetic fields- The summary (part 1)

Introduction

The solar system can be defined as the sun with all the planets, satellites and asteroids that move around it. The bodies in the solar system which have radius greater than 1000 km are likely to have dynamos that can generate magnetic fields (Jones, 2007). These bodies are the gas giant planets: Jupiter and Saturn, the ice rich planets Uranus and Neptune and the terrestrial planets, which contain iron rich cores, Mercury, Venus, Earth and Mars. Before explaining the solar system’ bodies one by one how they can drive their self-sustaining dynamos, first let we see the dynamo theory explaining that the magnetic field can be obtained through the conversion of mechanical energy (Merril, McElhinny & McFadden, 1998). From the Navier-Stokes equation we know that the Coriolis force has an important role to play in solving the dynamo problem. Therefore, the planets which have slow rotation may be difficult to drive a dynamo.

The external magnetic field

Source: http://astronomyonline.org

The magnetic field of the Earth consists of magnetic fields coming from several sources both internal and external source. The external magnetic field of the Earth is mainly from the interaction between the solar wind and geomagnetic field. The solar wind can be described as the movement of particles particularly H⁺, Helium and electron which are traveling from the Sun to the Earth and interacting with the geomagnetic field. This interaction leads to pressure to the geomagnetic field creating a cavity called the magnetosphere.