The concept of a "starting point" and an "end" on Earth depends on the perspective and context in which you are referring to them. Here are a few different interpretations:
Geographical Starting Point and End: The Prime Meridian, which runs through Greenwich, London, is often considered the starting point for measuring longitude. This line has a longitude of 0 degrees, and from there, longitudes increase to the east and decrease to the west until reaching 180 degrees at the International Date Line. However, it's important to note that this is an arbitrary convention chosen by humans for mapping and navigation purposes, and there is no inherent physical significance to these lines.
Geographical Starting Point and End for Circumnavigation: If you're referring to the starting and ending points of a complete circumnavigation of the Earth, then any location can serve as a starting or ending point. You can start at any point on the Earth's surface and return to the same point after traveling around the globe in any direction.
Astronomical Starting Point and End: In terms of celestial reference, one could consider the vernal equinox, which occurs around March 20th each year, as a starting point. This is the moment when the Sun crosses the celestial equator, marking the beginning of spring in the Northern Hemisphere. However, it's important to note that this is an astronomical event and does not have a physical location on Earth.
Symbolic or Philosophical Interpretations: In a symbolic or philosophical sense, the concept of a starting point and an end on Earth can vary greatly depending on cultural, religious, or personal beliefs. It could be interpreted as the birthplace of humanity, the place where life originated, or even philosophical concepts such as the alpha and omega, representing the beginning and the end.
Ultimately, the idea of a definitive starting point and end on Earth is subjective and can vary based on different perspectives and contexts.