AS101 Lecture Notes - Lecture 3: Pope Gregory Xiii, Sandford Fleming, Leap Year
Document Summary
In the sky, latitude is called declination and longitude is called right ascension. Another way of determining the length of a day is to measure the time it takes for any star to make successive passes across the local meridian which we call a sidereal day (pronounced sy-deer-ial). A sidereal day is about 23 hours 56 minutes. Timekeeping involving months comes from the lunar phase"s cycle, which is about. 29. 5 solar days, corresponding roughly to the average month length, known as a synodic month. Synodic comes from the latin word synod meaning meeting the meeting of the sun and the moon at each new moon phase. A sidereal year is longer than a tropical year by about 20 minutes, the difference due to the precession of the earth"s rotation. Sandford fleming, a canadian, proposed a system of dividing the earth into 24 different time zones such that within each time zone the time would be exactly the same.
