In this view, from 50° North towards South-West, the ecliptic runs oblique through the image. From Sun (below horizon, findable by crescent) through Moon towards the planets. The line between both planets is orthogonal to the ecliptic. This is a conjunction. (Perhaps this cinfused the ESO commentator - in our latidudes, planets above each other are indeed a sign of conjunction.) --Ikar.us (talk) 18:24, 3 July 2010 (UTC)[reply]
Seen in the en:WP article : "in the particular case of two planets, [a conjunction] means that they merely have the same right ascension (and hence the same hour angle). This is called conjunction in right ascension. However, there is also the term conjunction in ecliptical longitude. At such conjunction both objects have the same ecliptical longitude. Conjunction in right ascension and conjunction in ecliptical longitude do not normally take place at the same time, but in most cases nearly at the same time." (Right ascension is the celestial equivalent of terrestrial longitude.) Maybe are you focalising on only one kind of conjunction? --Myrabella (talk) 22:44, 3 July 2010 (UTC)[reply]
Let's think geometrically: At conjunction, the line between the two planets is orthogonal to the reference line (sky equator or ecliptic). The reference lines enclose an angle of 23°. That's the maximum difference in directions of the planet connection line for the two kinds of conjunction. If they happen near the vernal or autumnal point, and the difference of speed of the planets is small, the point of time and and the position will significantly differ between both types of conjunction, but the relative position of the planets, and the visual appearance of the side-by-side relation will still be very similar, with only 23° difference, being compared to the behind-relation, which is at least 67° different. --Ikar.us (talk) 12:18, 4 July 2010 (UTC)[reply]
