The following aspect interpretations apply only to natal or birth charts. Please see Synastry aspects for comparison charts, and Interpreting transits for transit aspects.
Jupiter opposition Ascendant (and thus conjunct the Descendant) indicates an externalization of Jupiter's energies. That is, expansion and strongly held philosophies are not usually encountered in these people, but rather by these people. At first glance, it would seem that any non-personalization of Jupiter's beneficial and expansionist nature would be bad for the native. This can be true, to some extent. When working or acting alone, people with this placement usually aren't the most lucky types. They may seem to lack any philosophical inclinations.
However, it is in one-to-one relationships that these people really come alive. They have an optimistic, cheerful nature around other people, and an ever-increasing amount of acquaintances that they can count on for a good chat. Through others, they learn about their own beliefs and morals; this usually makes them shrewd debaters (or, at least, somewhat eager to debate, though this is not necessarily to say they are eager to argue), as they are constantly learning about new belief systems so that they can find out what they think is best. They also are typically lucky in finding a spouse; the significant other is often optimistic and well-learned, perhaps foreign but certainly at least somewhat different from the native.
