Question about the obliquity of the ecliptic

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In summary, the question is about the obliquity of the ecliptic and how the Earth's axis of rotation and the locations of the poles and equator were determined. The answer is that the tilt of the Earth was easily measured by observing the altitude change of the sun with the seasons. The location of the equator can also be determined by watching the stars and sun. Early explorers used celestial navigation to determine their location in the arctic, and modern methods such as polar alignment scopes can align with the Earth's rotational axis even more accurately.
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plutoisacomet
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Question about the "obliquity of the ecliptic"

Hello guys, I hope I am in the correct forum for this question. If not, then I am sorry.
How was it determined that the Earth was tilted roughly 23 degrees from its orbital plane? Or, how did the current locations/definitions of the north pole, the south pole and the equator come about.
Thanks:
confused:
 
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  • #2
The poles are the axis of rotation of the earth, the equator halfway in between, and the tilt was determined from that (it is easily measured by measuring the altitude change of the sun with the seasons).
 
  • #3
Thanks for your quick reply RW. I understand that of which you have explained. I guess my question is how was the Earth's axis of rotation determined.
 
  • #4
plutoisacomet said:
I guess my question is how was the Earth's axis of rotation determined.
You can see it when you look at the North Star at night. The location of the equator can also be determined by watching the stars and Sun.

Early explorers of the arctic did, in fact, use celestial navigation to figure out where they were. It is actually slightly more complicated than just measuring the altitude of Polaris - Polaris isn't exactly on our polar axis.

My telescope has a handy-dandy polar alignment scope which helps me align it with the Earth's rotational axis to within a tenth of a degree or so. Then using several other methods, I can get even closer than that.
 
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  • #5
I see and thanks for clearing that up for me. I haven't had any Astronomy classes yet but I plan to take several.
Thanks again
 

1. What is the obliquity of the ecliptic?

The obliquity of the ecliptic, also known as the axial tilt, is the angle between the plane of the Earth's equator and the plane of its orbit around the sun. It is currently approximately 23.5 degrees.

2. Why is the obliquity of the ecliptic important?

The obliquity of the ecliptic plays a crucial role in determining the Earth's seasons and climate. It affects the amount of sunlight that reaches different parts of the Earth's surface, which in turn influences temperature and weather patterns.

3. How does the obliquity of the ecliptic change over time?

The obliquity of the ecliptic is not constant and changes over time due to gravitational interactions with other planets in our solar system. It has varied between 22.1 and 24.5 degrees over the past 5 million years and is currently decreasing at a rate of about 0.47 degrees per century.

4. What are the potential effects of a significant change in obliquity?

A significant change in obliquity could have significant impacts on the Earth's climate. A larger tilt could result in more extreme seasons, while a smaller tilt could lead to milder seasons. It could also affect the strength and location of ocean currents and winds, potentially altering global climate patterns.

5. How do scientists measure the obliquity of the ecliptic?

The obliquity of the ecliptic is measured through observations of the Earth's position in relation to the sun and other celestial bodies. Astronomical instruments such as telescopes and satellites are used to track the Earth's movements and calculate its axial tilt. Historical records and geological evidence can also provide information about past changes in obliquity.

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