AS101 Lecture Notes - Equinox, Ophiuchus, Farthest North
Document Summary
Quasar: a type of extremely bright galactic core containing a super-massive black hole. The earth is closest to the sun at the beginning of january. Our winter is at the same time as the southern hemisphere"s summer, and vice versa. Any explanation of the seasons must explain why they are opposite in the northern and southern hemispheres, and cant depend only on our distance from the sun. A few terms describing the local sky wherever you are standing: zenith: the point directly above your head: Meridian: a north-south line passing through the zenith. Horizon: all points at 90 away from the zenith. (where the ground meets the sky) Great circle: on the surface of any sphere, a circle whose centre is the same as the centre of the sphere (for example, the equator is a great circle, but other latitude lines are not. )
