Question

1.Suppose the combined weight of Santa and your large gift so big and heavy that it increased the earth’s wobble and tilted the planet on its axis to 24 degrees. Would the winter be longer or shorter? your location: North America ( Detroit)

2. Suppose a golden plover, who are renowned for their migrations, left the North Pole for the South Pole. What longitudinal line should the bird follow for the shortest distance to travel? Why is it shortest? Hint: This would also be the shortest route for a whale.

Answer 1

1.Suppose the combined weight of Santa and your large gift so big and heavy that it increased the earth’s wobble and tilted the planet on its axis to 24 degrees. Would the winter be longer or shorter? your location: North America ( Detroit)

a.) The  motion that is familiar to us is that the Earth rotates around the Sun once a year. In fact, that is what is meant by a "year". This motion too is not utterly regular. We know this because of the need to introduce a Leap Year from time to time in the calendar to compensate. The Earth rotates around the Sun on average once every 365.2422 days; not exactly 365 days as the calendar would suppose (see Leap year or details). So we need to adjust the calendar every now and them to make it coincide with the actual rotation period. This motion too is not entirely regular and varies around the 365.2422 day average.

* The rotation of the Earth around the Sun in a year is recognized by the four seasons. The orbit is not exactly circular. It is an ellipse with the Sun at one focus as Kepler recognized centuries ago (his First Law). This means that sometimes the Earth is closer to the Sun than at other times. If you go to Satellite in Orbit you will see a demonstration of a satellite revolving around the Earth but it is exactly how the Earth revolves around the Sun. But this elliptical orbit is absolutely not the reason why we have seasons (although apparently 85% of all people when asked why we have seasons will reply that it has to do with how close the Earth is to the Sun). The earth is actually furthest away from the Sun on July 4th so the distance to the Sun cannot govern the change of seasons or July 4th would be in mid winter. And remember that when it is summer in the northern hemisphere it is winter in the southern so distance from the Sun cannot be the answer to the season phenomenon. Obviously distance must make some difference -- the planet would be much hotter if we were much closer, but it is not the reason we have seasons.