I'm trying to understand this one. Let's imagine we want to launch a satellite to the perpendicular-to-the-plane-of-the-ecliptic orbit ("passing through the North and South ecliptic poles", or perpendicular to the Sun-Earth line, through the Earth). Since the Earth's axial tilt is around 23.4º, would the inclination of this orbit (and the azimuth of the rocket launch) be 113.4º (90+23.4)? (I think so!) Or maybe would it be 66.6º (90-23.4), as I've been suggested elsewhere? And a couple secondary questions: 1. If it is 113.4º, this is a retrograde orbit, isn't it? 2. Would this be most probably an Earth-centric orbit or an Heliocentric orbit? 3. Have you heard of any real satellite using this orbit? Sorry for my English, it's not my primary language, hope you'll understand! Thank you in advance for your answers!