Bibliography

1.    W.J. Kaufmann,  Discovering the Universe, W.H. Freeman and Company, 

1987

2.    M. Marten &  N. Henbest, The New Astronomy, Cambridge University Press,     

1983

3.    Association of Lunar and Planetary Observers web page / Solar section

        http://www.lpl.arizona.edu/alpo/

4.    J. Mitton, The Penguin Dictionary of Astronomy, Penguin Books, 1993