Kelvin MacKenzie is all set to front a C5 programme on libel, and with thirteen years experience as editor of The Sun, he has to be an expert. MacKenzie is also a Libran (October 22 1946), associated with the symbol of the Scales of Justice, and all Librans profess themselves to be believers in fair play - and fair comment.

In practice, many love 'n' peace Librans tip the scales right over and are a bolshie and outspoken lot - John Lennon, Bob Geldof - and MacKenzie is clearly one of the bolshies. The real strength in his horoscope comes from his punchy and provocative Scorpio planets. Communications Mercury is joined to aggressive Mars, and this is tabloid talent at its best - terse, sharp, cutting, sexy and wickedly funny. Astrologers reckon that this planetary combination has " very great mental energies, especially of a controversial and disputative kind. It is virile, aggressive, and satirical...it may cause breakdown from over- work, quarrelsomeness, discontent, and the making of many enemies. But it never lacks energy and courage, and it is entitled as a rule to respect for its sincerity and downrightness... It is good for all kinds of polemic writing." (Charles Carter, Astrological Aspects).

Something MacKenzie might like to bear in mind is that the Roman orator, Cicero, had this same Mercury-Mars line-up, but the damages for libel and slander were rather more punitive then. Cicero's criticisms so enraged Mark Antony's wife that, after his death, she "pierced his tongue with a bodkin".

In the past, shocking and independent-minded Uranus has been dominant in MacKenzie's horoscope, and since pioneering Talksport Radio he has enjoyed being a rebel with a cause in his fight with the BBC over its license fee and 'unfair' advantage (clock the Libran complaint!). But this innovative Uranus, which has served him so well in the past, is moving out of the picture for the next few years.

So does the C5 venture represent a whole new media phase for Mackenzie, especially moving into television? It is probably a straw in the wind for his desire to do something completely different. Librans are full of ideas, most of them impractical and the rest of them impossible, and they are prone to move the goalposts when their schemes don't pan out, or they don't get the lively response they want. It could be that Mackenzie has had enough of the executive game and is running out of enthusiasm and steam in his work at TalkSport Radio. He's looking for a more personally challenging project where his cut-and-thrust Mercury- Mars can keep its keen edge. Saturn, planet of frustration and delay, holds him back for a while but come early 2004, expect his voice to be virile and aggressive again.