There’s been some debate about when Rahu and Ketu change signs this year. I’ve been using the Mean Node, which says it happens on June 8th, 2011. Many others have used the True Node, which has the change of signs set for this morning.
Here is a description of the differences that I found on a forum…
“The Moon’s Nodes are the points where the orbit of the Moon crosses the plane of the ecliptic (the plane of the ecliptic is the path that the planets travel around the Sun). Where that orbit crosses from South (below the ecliptic) to North (above the ecliptic) is called the North Node, and the opposite crossing is the South Node.
Before there were computers, astrologers had to manually calculate the positions of all the points on a chart by “interpolating” from astronomical tables that showed the positions once each day. So for example, if your Moon was in 2 degrees Aries at Midnight before you were born and 14 degrees Aries at Midnight after you were born, it moved 12 degrees in 24 hours, or about half a degree per hour. Then if you were born at 8 o’clock in the morning, you could figure that the Moon had moved 4 degrees since midnight (8 hours times half a degree = 4 degrees), so your Moon would be at 6 degrees Aries (2 degrees at midnight from the ephemeris plu 4 degrees that it moved in the 8 hours until you were born).
Now this method of figuring where the planet is at any given tim between one midnight and the next midnight works perfectly as long as the planet moves
at a constant rate of speed. But if it speeds up and slows down over the course of the day, then this way of calculating only gives you the average (“mean”) motion per hour … in the example above, the moon might actually move a little bit more than half a degree one hour and a little bit less than half a degree the next hour … so what you are calculating is really the position according to the planet’s Mean (average) motion rather than its True (exact) motion over those particular hours.
In practice, the motion of all the planets (and the Moon) is regular enough that the difference between the True and Mean positions is so slight as to be
virtually identical. The Moons nodes, however, do speed up and slow down enough during the day that there is a tiny but measurable difference between the Mean and True positions. Before computers, it was impossible to calculate the True position of the nodes without spending hours at celestial mechanics equations, so the Mean nodes were always used. Now that computers are commonplace, the True nodes can be calculated.
However, since the Mean nodes were used for thousands of years, many astrologers still prefer to use that method even though it is a tiny bit inaccurate. That’s the only difference between the True and Mean North Nodes. The difference is usually so small that it’s not worth worrying about (unless you’re a Virgo! ) Hope this helps.”
While I’m all for using the actual position, which is one reason I like Vedic Astrology so much, because it is sidereal, but it may be that the information provided about Rahu and Ketu as it moves through the signs, in light of the old texts, might reflect the Mean Node, since that is the information they had to work with.