According to my calculations, using Vedic astrology birth rectification concepts, Jay Leno has an Aquarius rising sign (April 28, 1950). For someone to be a successful TV personality; Venus, third house, second and seventh has to interact and the person has to have strong periods (running dasas) operating during their lifetime to have success and fame. Mercury's interaction on any one of these houses or house of profession is a welcome feature. One can find some similarities in Johnny Carson's and Jay Leno's chart, though they both have different rising signs.
Jay Leno's 10th lord of profession is also 3rd lord Mars. This is very well placed in the seventh house of business partners and public interactions. Mars itself is in the constellation (lunar mansions) of a powerful Sun. And this exalted Sun is placed in third house of Mars thereby exchanging signs (termed as parivarthana in Vedic astrology). Venus, planet of art and an excellent planet for Aquarius rising sign that can give luck and fame is well placed in the ascendant itself with Jupiter a planet that can bestow enormous wealth for this ascendant. Leno's Mars period starting April 1976 was a notable period that vaulted him into comedy circuit. This followed by Rahu period (Rahu is the Moon's north node) starting 1983 to 2001. It is during this period that Leno established himself as a top-rated professional. Rahu's period gave him the riches and fame as it is in the constellation of ascendant lord Saturn and is aspected by Mars, the planet of profession. Jupiter's period is running since 2001 and currently Leno is in Venus sub-period (2009 March to 2011 November).
Venus sub-period has given some minor health issues and career ups and downs to Jay Leno. It must be noted that Venus in his chart is well placed but is aspected by Mars and Saturn, two malefic planets that can cause disturbance when transits also support an event. Important planets, such as Jupiter and Rahu in 2009 were transiting the house of retirement, long vacation and losses. In addition, transit Saturn in Leo was exactly at 29 degrees over his natal Mars, in the first two weeks of September 2009 that also caused changes to Leno's career. But the recent events suggests that this was not a smooth career transition as his ratings dropped and his Show will likely move back the original slot of 11:35pm. The reason for slump in ratings is due to transit Saturn's aspect on his tenth house of profession, after Sep 2009, and transit Mars that is in its debilitation sign of Cancer till May 2010. So, one can expect the transition to be rough with many ups and downs. A retrograde Saturn from January 13, 2010 till May 2010 will also, make the transition bumpy with roadblocks.
(January 12, 2010)