1 However the origin of our solar system is explained questions still remain unanswered and are the focus of research by scientists around the globe.
Are there other planets outside of our solar system If there are, are they able to sustain life What techniques have been employed to study these planets and other heavenly bodies when they are light years away from us These are just a few of the crucial questions that scientists try to answer since Galileo Galile' invented the telescope in the early 1600s.
How does one differentiate a planet from an asteroid or from any other celestial body In an article by Samantha Harvey posted at the NASA e-magazine, planets have been defined as "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and (c) has cleared the neighborhood around its orbit." At the same time, new moons are also being discovered, both around existing planets and within these mysterious new worlds. Once the existence of a moon is confirmed and its orbit determined, the moon is given a final name by the International Astronomical Union (IAU), the organization that assumed this task since 1919.2
Though space has always been there, it was only in 1957 that a spacecraft was actually sent into space to measure what it is like. Until 1991, only the planets in our solar system are the only known planets. Nevertheless, astronomers did not believe that our Sun's environment was the only planet producer in the universe. Yet they had no evidence of planets outside our solar system.
Not until 1991 that radio astronomers detected the first extrasolar planets orbiting a dying pulsar star. This extrasolar planet is a remnant of a supernova explosion in the constellation Virgo hence is not able to sustain life because of the deadly radiation it emits. Then, in 1995, Swiss astronomers found another extra-solar planetary candidate. This star, found in the constellation of Pegasus, is much more like our Sun with respect to its temperature, size, rotation speed and emitted radiation. Although this is also considered not a good candidate to sustain life, it was the first ever evidence of an extrasolar planet around a Sun-like star.3
Other concern in studying extrasolar worlds is whether life may exist there. Variables like size, distance and temperature will serve as indicators that a particular extrasolar planet may be considered a life-bearing planet.
Basic techniques being employed to accomplish such