[Page no. 8.]
[Title: The Search for Extrasolar Planets]
[Image: Caption: An artist's view of an exoplanet!]
Since the first discovery of a planet around another normal star in 1995 we have known of the existence of extrasolar planets ("exoplanets" for short") - and later also of extrasolar planetary systems - although so far, only giant, Jupiter-like planets have been discovered. By mid-2001, astronomers have found nearly 70 extrasolar planets and at least three other planetary systems (with more than one planet.
The fact that no Earth-like planet has been found until now is above all because of the limitations of current astronomical telescopes and instruments. They are not "sensitive" enough to finding smaller, Earth-like planets around foreign stars. The lightest explanet found so far weighs about 50 times more than the Earth.
However, great efforts are now being made to improve the situation. New, extremely powerful instruments at the largest telescopes on the ground and soon also in space will be able to search for smaller planets around nearby stars.
This is a scinetific discipline in very rapid development and discoveries are made all the time. Who knows what next week will bring to us?
There are several active groups of scientists working in this field with ground-based telescopes. The latest news may be found at some of the main websites, from where there are also many links to related webpages:
In addition to ground-based observational programmes, various space missions are also being planned that will search for exoplanets above the disturbing effects of the Earth's atmosphere. The include:
The possibility of life around the exoplanetary systems, and how those lifeforms may be different from our own, can be evaluated and investigated with current theoretical models.
Maybe we are now close to beginning to grasp little bits and pieces of the answers to some of the related key questions: