By Gladstone C. Walling, Contributor
IT IS no longer science fiction to speculate about the existence of planets in solar systems other than our own, because new technologies in astronomy, have expanded the search for planets outside our solar system the extra-solar planets. New technologies have also assisted astronomers to accumulate data that provide proof that such planets do exist.
Many of us are very familiar with our Solar System. It consists of the Sun at the centre of the system and nine planets gravitationally held in separate elliptical orbits around the sun. Not only do the planets vary in distance from the sun, but they also vary in size; Jupiter, a gas giant, is the largest planet with a diameter of 142,984 km orbiting the sun at an average distance of 778.4 million km. In contrast, the planet Earth, on which we live, is a terrestrial or rocky planet with a diameter of 12,656 km and orbits the sun at an average distance of 148.6 million km (1 AU. Astronomical Unit).
In 1995 the exalted single status of our Solar System was changed to that of "another solar system" in our Galaxy. That was just the beginning. As of January 2003, astronomers have so far discovered 91 other planetary solar systems with 105 planets distributed between them. Of the 91 solar systems, they have so far identified 12 multi-planet systems.
In 1995, the discovery was made of eight extra-solar planets orbiting sun-like stars. Michael Mayor and Didier Queloz of the Geneva Observatory were the first astronomers to detect the presence of the planets orbiting a sun-like star. The first planet was discovered orbiting the star 51 Pegasi, in the constellation Pegasus. Soon after Geoffrey Marcy and R. Paul Butler in their survey of some 107 stars discovered six new planets.
It was interesting to note that the first nine stars, around which the planets were detected, were very much like our own star, the Sun. Most of the stars were spectral type G stars and had masses similar to our sun. Many of these planets had masses greater than or similar to the mass of Jupiter.
Please do not take your telescope out into the night to hunt for these planets. Amateur Astronomers like us do not yet have the technology to image these planets. A planet "shines" only due to the reflected light of its sun and therefore will be about a billion times fainter than its star.
The other problem is the relational closeness of the planets to their suns and it is for that reason that planets are lost in the glare of their star's light. The planets are therefore not detected by observation through a telescope but by the effect of the planet on the parent star. The parent star wobbles due to the gravitational pull the planet exerts on it. Extra-solar planets are detected using a number of cleaver scientific methods.
Gladstone C. Walling,
president, Astronomical Association of Jamaica;
member, Council of the
Jamaica Association of Scientists & Technologists.
