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How Do We Know That The Earth’s Rotational Axis Is Tilted By 23.5 Degrees Relative to its Orbital Plane?

-- Paul | March 18, 2020

Question:

How do we know planet Earth is tilted 23 degrees?
And, who came up with that?
Basically, where is the proof?

-- Paul

Answer:

The fact that we have seasons on Earth tells us that our planet does not rotate on its axis in the same plane that it orbits the Sun. The tilt of our rotational axis leads to longer days in the summer time and longer nights in the winter. Seasonal changes and changes in how the Sun moves through the sky during a year are probably the most direct indications that Earth’s rotational axis is tilted.

-- Jeff Mangum

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