Exoplanets » Introduction

The distances between the stars is stupendous and is measured in light years. The speed of light is 299,792.458 km/s in a vacuum. For practical purposes it is stated as 300,000 kilometres a second or 186,000 miles per second. A light year is very close to 9,500,000,000,000 kilometres or nine and a half trillion kilometres. The Sun is about 8 light minutes from the Earth. The closest other star, Proxima Centauri, is over four light years away from our Solar System.

It is a tribute to modern science and technology that since the first discoveries in 1995 astronomers have been detecting more and more planets orbiting other stars. Almost all of them have been Gas Giants, many more massive than Jupiter. A few smaller ones the mass of Saturn and even Neptune have been detected. Most of the planets have been discovered by the 'gravitational wobble effect'. The method is however not yet sensitive enough to find Earth sized rocky type planets and it is another method that is being used to find the 'holy grail' of planets similar to our Earth with the possibility of life. The method now being developed depends on the tiny decrease in the light received when a planet transits across the face of a star. For example when Venus transits the Sun there is a very tiny diminution of the sunlight due to the transit. The same will be true of other stars.

The illustration on the left shows a diagram of the transit of Venus on 8 June 2004. (Credit ESO). Transits are infrequent. Next one is due on 6 June 2012. Next pair will be 2117 and 2125. Two missions are now actively investigating transits of planets passing in front of other stars. There is however one small problem. The diminution assumes that the starlight is constant during the transit, which will not necessarily be true. This means that some way must be found to measure the changes in the luminosity of the star during the transit so that the REAL EFFECT due to the transit of the planet can be calculated. This requires extremely sensitive instrumentation. The two missions are the French led CNES/ESA COROT Mission and the NASA's Kepler. Both missions are investigating the transits of extrasolar planets across the face of the star and the changes in the stars themselves. Changes that occur in stars form the basis of the new science of ASTEROSIESMOLOGY. There was in fact a stand at the recent Exhibition at the Royal Festival Hall celebrating the 350th Anniversary of the founding of the Royal Society. (July 2010).

Ray Goodwin

Somewhere there are mountains
Glistening in the snow
Somewhere there are mountains
That we shall never know

Somewhere there are rivers
Flowing fast and free
Somewhere there are rivers
That we can never see

Somewhere there are oceans
And sun drenched island sands
Forests full of creatures
In vastly distant lands

Somewhere there’s a planet
Beneath an alien star
The people watch our tiny sun
And wonder where we are

One day perhaps we’ll find them
Across the void of space
Perhaps through ways as yet unknown
We’ll meet them face to face

The author of this web site Ray Goodwin holds B.Sc. Degrees from London University in Chemistry, Geology and Physiology and an M.Sc. in Biochemistry. He has spent most of his professional life teaching in Colleges of Technology. On his retirement he has entered the fields of astronomy, astrochemistry, astrobiology and space sciences. He has spent a great deal of his retirement in visiting amateur astronomy societies and in attending European Space Agency Symposia in ESTEC in the Netherlands and other scientific conferences in England and Sweden. He regularly attends the yearly European Astrofest in South Kensington London and other meetings in the UK. He has written scientific articles and given a number of lectures on diverse scientific subjects.

Readers of this web site are invited to e-mail the author ( ray@lifeinthecosmos.com) and discuss their opinions of the topics dealt with and suggest any changes which they think may be helpful.

Life in the Cosmos Website
Version 01.00 - April 20, 2015.