Midheaven, Ascendant, Nadir, and Descendant are "points
Franklin,
The Midheaven, Ascendant, Nadir, and Descendant are very important "points" in a chart, which indicate a person's outer world, self, inner world, and others. These "points" are created by combining the two halves of the astrological chart: left and right, and top and bottom (for more on this see:
http://www.geocities.com/wilsontctc ). These are "points" and not planets because:
- they do not rule any houses in the chart
- they have no energy in themselves, but simply indicate where a person's attention is focused
You CAN use these "points" as an indicator to the sort of planetary energy a person brings to these focuses. For example, if Virgo (ruled by Mercury) modifies the Midheaven (outer world), then the person in the outer world uses their energy in a Mercury way, and you would look to Mercury in the chart to better understand how the person uses Mercury.
Chiron is a different story because it HAS energy, and may also rule one of the 12 houses in the chart. However, since no one yet can agree on WHICH house it rules, it is kind of a "disconnected" planet: very powerful in a chart, and yet it doesn't clearly fit into the house rulership system. For more about the house rulership system, see the above link.
It is simplest if you stick with the 10 planets in doing any "energy analysis" of the astrological chart.
Explaining,
Tim