The Jovian Planets

The planets outside the orbit of Mars are called as Jovian planets because their structure is similar to that of Jupiter. These are all gaseous bodies. They have ring systems around them and have large number of moons.
Jupiter is a very bright object in the sky. It can be easily seen with the naked eye. It is the largest and the most massive planet in the solar system. It has a very deep atmosphere, mainly of hydrogen and helium. Because of its large mass and size, Jupiter exerts a strong gravitational pull on other objects which pass by it. The next three planets Saturn, Uranus and Neptune are similar to Jupiter. Saturn has the most beautiful and visible rings. The last planet Pluto is so small that it cannot be observed from the earth and no space mission has been sent into it yet.

Electro Encephalogram(EEG)

Electro Encephalogram shortly called EEG is used to record the electrical activity of the brain. This electric al activity is measured in the form of electric potentials. This process is called as Electro Encephalography. By placing two electrodes on the scalp of the patient, and leading via suitable amplifier to a CRT or to a ink-writing device, a record of four different types of waves can be obtained. These waves are named as alpha, beta, delta and theta. They vary in their frequency. These waves give the characteristic activity of the brain, and that is useful for study of brain problems like tumors, cerebral palsy, etc.