Rahu (The North Node of Moon) and Ketu(The South Node Of Moon) are not only important in Vedic Astrology, but also in Hindu mythology. Most of the times you keep hearing about the myth in which lord Vishnu beheaded Rahu-Ketu(Which was just 'Rahu' earlier). Rahu is just head but no body, therefore it has desires; desires to possess, to win, to use and to exploit. Not just that, the desire to break taboos is also a prominent expression of Rahu in nativities. Since Rahu only has a head, all it could do is to have cerebral pleasures. It could scheme, covet, think and shout; but it could never get satisfaction, ecstasy, peace and rest.
Kethu, on the other hand is all body and no head. It cannot scheme, plan, possess or think; therefore it's ever detached. It's a failure in society, but if controlled, it's a grand success in spirituality. Since it has no head, it can very easily meditate, be at peace with itself and bliss of existence showers on it at the expense of social connections.
Yesterday, Moon was in the sign Scorpio. Rahu is also transiting through Scorpio and it was reported that there was a lunar eclipse, witnessed only in a few regions across the globe. Moon travels through various signs at a swift speed and returns to a sign after every 27 days, which might mean that there should be a lunar eclipse once every 27 days, as Moon would be transiting through the sign in which Rahu is situated once every month. But it doesn't happen. Moon, when it's brightest, that's when it gains 'Paksha-Bala', and in the sign through which Rahu is transiting, might undergo eclipse.
That is why, not all the people who are born Moon conjunct Rahu are born at the time of lunar eclipse. Looking at Rahu and Kethu is difficult for Astronomers. The eclipses, lunar and solar, are the most evident forms of Rahu and Kethu for them, but as far as Astrologers are concerned; Rahu and Kethu are very perspicuous objects. In lunar eclipse, Rahu eclipses the rays of Moon, therefore, people born during this time don't enjoy a very healthy activity of mind and hence have something always lacking with regards to health. The yoga is termed as 'Chandaal Yoga'. Combination of Rahu with most of the planets is considered inauspicious for spiritual reasons, but it might confer great taboo breaking social capacity on some natives.