Tilt of Earth's Equator: Arctic, Antarctic, Tropics

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SUMMARY

The discussion centers on the implications of Earth's axial tilt being 177.4° instead of the current 23.5°. This significant change would affect the latitudes of the Arctic and Antarctic Circles, as well as the Tropics. Specifically, the Tropics would be located at +/- 177.4°, while the Arctic and Antarctic Circles would be defined by the new tilt, leading to a complete redefinition of these geographical markers. The conversation emphasizes the relationship between axial tilt and solar positioning, particularly during solstices.

PREREQUISITES
  • Understanding of axial tilt and its effects on solar positioning
  • Basic knowledge of Earth's geographical markers: Arctic Circle, Antarctic Circle, Tropics
  • Familiarity with the concept of retrograde motion in planetary science
  • Ability to visualize geometric relationships in a spherical context
NEXT STEPS
  • Research the effects of axial tilt on climate and seasons
  • Explore the concept of retrograde motion in detail, particularly in relation to Venus
  • Study the historical naming conventions of the Tropics and their astrological significance
  • Examine the implications of extreme axial tilts on planetary habitability
USEFUL FOR

Astronomy students, astrophysics researchers, educators in Earth sciences, and anyone interested in the effects of planetary tilt on climate and geography.

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Homework Statement



Suppose the tilt of Earth’s equator relative to its orbit were 177.4◦ (like Venus) instead of
23.5◦. At what latitudes would the Arctic and Antarctic Circles and the two Tropics be lo-
cated?


Homework Equations



N/A


The Attempt at a Solution



I would like someone to help me make a mental image or reword this for me as this is probably the easiest question on a large astrophysics assignment I have but I am having trouble picturing this and understand how Venus's retrograde motion works.
 
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mozartkart said:

Homework Statement



Suppose the tilt of Earth’s equator relative to its orbit were 177.4◦ (like Venus) instead of
23.5◦. At what latitudes would the Arctic and Antarctic Circles and the two Tropics be lo-
cated?


Homework Equations



N/A


The Attempt at a Solution



I would like someone to help me make a mental image or reword this for me as this is probably the easiest question on a large astrophysics assignment I have but I am having trouble picturing this and understand how Venus's retrograde motion works.

The latitudes of these great circles are related to the tilt of the planet.

For example, if the inclination from the vertical is i, then the tropics are at latitudes +/- i. These circles represent the greatest deviation from the equator where the Sun can appear directly overhead; i.e. the circle of greatest altitude of the Sun, occurring on the Solstices.

The arctic and antarctic circles are the limits where the Sun can be above the horizon or below the horizon for an entire day.

Draw a circle representing the Earth and draw lines through the center tilted 23.5° to the horizontal (+ and - 23.5°). Their intersection with the circle represents the limits of the Sun's maximal excursion North and South for being directly overhead; those are the Tropical limits.

Do the same with lines tilted 23.5° from the vertical. These lines intersect the surface at the limits of the arctic circles.

Now draw a new circle and draw lines with tilts of +/- 177.4° . Note the intersections and compare to those for the Earth's circle.

The remaining questions are how do you designate North and South poles to name the arctic versus the antarctic circles, and what will be the naming convention for the Tropical latitudes, which were originally astrologically named from an Earth perspective (in which constellations is the Sun when it reaches the solstices?).
 
gneill said:
The latitudes of these great circles are related to the tilt of the planet.

For example, if the inclination from the vertical is i, then the tropics are at latitudes +/- i. These circles represent the greatest deviation from the equator where the Sun can appear directly overhead; i.e. the circle of greatest altitude of the Sun, occurring on the Solstices.

The arctic and antarctic circles are the limits where the Sun can be above the horizon or below the horizon for an entire day.

Draw a circle representing the Earth and draw lines through the center tilted 23.5° to the horizontal (+ and - 23.5°). Their intersection with the circle represents the limits of the Sun's maximal excursion North and South for being directly overhead; those are the Tropical limits.

Do the same with lines tilted 23.5° from the vertical. These lines intersect the surface at the limits of the arctic circles.

Now draw a new circle and draw lines with tilts of +/- 177.4° . Note the intersections and compare to those for the Earth's circle.

The remaining questions are how do you designate North and South poles to name the arctic versus the antarctic circles, and what will be the naming convention for the Tropical latitudes, which were originally astrologically named from an Earth perspective (in which constellations is the Sun when it reaches the solstices?).

Thank you for your help, this was really easy to picture and made my point of view much clearer. Have a great day/night :D
 

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