What Is The Tropic Of Capricorn?

The Tropic of Capricorn is the terrestrial parallel located approximately 23.5 ° south latitude. It joins the southernmost points, that is, the areas located further to the south of the Earth on which the sunlight falls from a zenith (completely vertical) once a year.

The Tropic of Capricorn is, therefore, one of the multiple imaginary lines that cross the globe horizontally (parallel). These reference lines can be imagined as if they were belts that surround the Earth at different heights and that get smaller as they get closer to the poles.

The parallel that is used as a starting point to locate the others is the equator, a circular line that surrounds the earth horizontally, dividing it into two halves or hemispheres (north and south).

Therefore, the Tropic of Capricorn is an imaginary reference line (parallel) that is located in the southern hemisphere of the earth. Specifically, this line is located at an approximate latitude of -23.5 ° (or 23.5 ° south) with respect to the equator, taking into account that latitude measures the distance at which a geographic point is with respect to the equator ( latitude 0).

While the Tropic of Capricorn is located in the southern hemisphere of the planet, the Tropic of Cancer is its equivalent in the northern hemisphere or half of the globe located above the equator. Specifically, the Tropic of Cancer is located at a latitude of approximately + 23.5 ° or 23.5 ° North.

Article index

  • one

    Through which countries does the Tropic of Capricorn pass?

  • two

    Which countries are completely below the Tropic of Capricorn?

  • 3

    What is the origin of the name of the Tropic of Capricorn?

  • 4

    What is the Tropic of Capricorn for? 

    • 4.1

      1- The tropic of Capricorn and the December solstice

    • 4.2

      2- The Tropic of Capricorn as the limit of climatic zones

  • 5

    References

Through which countries does the Tropic of Capricorn pass?

By Maose [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], from Wikimedia Commons

Imagine the Tropic of Capricorn as a circle that crosses those areas further south of the Earth on which the sun’s rays can hit completely vertically. The imaginary line drawn would therefore pass through all those territories that are located at a latitude of 23.5 ° south.

Thus, the Tropic of Capricorn crosses geographical points located on three continents and in more than ten different countries that, ordered from west to east, are:

  • America: Chile, Argentina, Paraguay and Brazil.
  • Africa: Namibia, Botswana, South Africa, Mozambique, and Madagascar.
  • Oceania: Australia and French Polynesia (a territory located in Oceania but belonging to France).

As a curiosity, it should be mentioned that Brazil is the only country in the world with territories located in geographical points that will be crossed by both the equator and the Tropic of Capricorn.

Of course, the imaginary line drawn along Earth’s latitude 23.5 doesn’t just cross the mainland. On its journey, the Tropic of Capricorn also passes through three different oceans: the Pacific Ocean, the Atlantic Ocean and the Indian Ocean.

Which countries are completely below the Tropic of Capricorn?

On the other hand, there are countries that are entirely south of the Tropic of Capricorn, without touching or exceeding this imaginary line with any geographical point. In the southern hemisphere, only three states have their entire territory below 23.5 ° south latitude marked by the Tropic of Capricorn.

Interestingly, this is a very small number compared to the 74 states that lie entirely above the Tropic of Cancer in Earth’s northern hemisphere. This difference is due to a very simple reason: the percentage of land in the northern hemisphere is vastly higher than in the southern hemisphere.

The three countries that lie completely below the Tropic of Capricorn are, from west to east:

  • Uruguay, the only country in the American continent located in an integral way more to the south of this brand.
  • Swaziland and Lesotho, two very small countries located in southern Africa.

There is a very interesting debate surrounding the inclusion of a fourth country on the list: New Zealand. It is true that the main body of its islands is completely below the Tropic of Capricorn. However, there are small archipelagos dependent on the Kingdom of New Zealand that are located at coordinates above 23.5 ° south latitude: Cook Islands, Tokelau and Niue.

What is the origin of the name of the Tropic of Capricorn?

By Caliver [CC0], from Wikimedia Commons

The term tropic comes from the Greek ( τροπικός ) and means “back”. In the astronomical field, the word tropic is used to designate the latitudes located further north (Tropic of Cancer) and further south of the Earth (Tropic of Capricorn) on which the Sun can reach the zenith, that is, its greatest height. in the sky.

This means that, at a certain time of the year, the Sun strikes completely perpendicular to the earth’s surface marked by the location of the Tropic of Capricorn. The phenomenon is called the solstice.

The origin of the name of the Tropic of Capricorn dates back to about 2000 years ago. When in Classical Antiquity, the solstice was observed in the southern hemisphere, the Sun was in the constellation Capricorn, hence its name.

Currently, this star is not in this constellation when once a year it reaches its zenith in the southern hemisphere of the earth. However, the traditional name has remained throughout the centuries and to this day.

What is the Tropic of Capricorn for? 

The Tropic of Capricorn is a parallel associated with a latitude that has had great relevance, even since Classical Antiquity. The latitude line around the Earth marked by this tropic is fundamental for disciplines such as Geography and Astronomy. Why?

Both sciences use the terrestrial zones delimited by the Tropic of Capricorn (and by its equivalent in the northern hemisphere, the Tropic of Cancer) as a reference to locate a series of natural phenomena. What event occurs at this terrestrial latitude?

1- The tropic of Capricorn and the December solstice

What relates the Tropic of Capricorn to the December solstice?

In the southern hemisphere, where the Tropic of Capricorn is located, a solstice occurs once a year – usually sometime between December 21 and 23. It is what is known as the December solstice. But … what does this mean?

It means that there is an important relationship between the Tropic of Capricorn and the phenomenon known as the solstice that has been briefly discussed earlier.

And it is that the Tropic of Capricorn is the parallel or imaginary line that joins the terrestrial areas located further south of the Earth whose surface can be reached once a year by the solar rays in a completely vertical way. The time when this occurs is known as the December solstice.

During this solstice, the Sun reaches its highest apparent height in the sky and the Sun’s rays fall vertically (forming an angle of 90º with respect to the ground) on the areas of the southern hemisphere that are in the latitude marked by the Tropic of Capricorn. This specific position of the Earth with respect to the sun, can be visualized using the analogy of a light bulb that hangs exactly above us, shining its light vertically on our head.

The Tropic of Capricorn is, therefore, the latitude limit where the Sun can reach the zenith. Beyond these lines (for example, in Uruguay) the Sun will never have this position with respect to the Earth’s surface.

Although the solstice may seem like a very complicated phenomenon, its observation is very simple without even having high technology. In fact, with a stick, some stones and the observation of the sky, the Sun and the projected shadows is enough.

Therefore, experts maintain that it is a phenomenon of which the oldest civilizations were aware. In fact, there are authoritative voices that propose that even our Stone Age ancestors already had such knowledge. 

What are the consequences of the December solstice?

The visible consequences of such natural behavior are reversed in each hemisphere. That is, during the solstice that occurs at a certain time between December 21 and 23 each year:

  • In the southern hemisphere the Sun reaches the maximum height at which it will be seen in the sky throughout the year. The star even affects vertically on the latitude marked by the Tropic of Capricorn. This will be the longest day of the year and the one that gives way to summer but only in the southern half of the planet.

For this reason, the solstice that occurs in December is known as the summer solstice in the southern hemisphere.

  • If the Sun reaches its maximum height over the southern hemisphere, the northern hemisphere of the earth is positioned so that said star is at its lowest apparent height in the sky with respect to it.

For this reason, this solstice is known as the winter solstice in the northern half of the planet, since it marks the arrival of this season and the longest night of the year for the northern hemisphere.

The same is applicable to the Tropic of Cancer, previously identified as the northern counterpart of the Tropic of Capricorn. The Tropic of Cancer crosses the northernmost latitudes on which the Sun can affect from zenith. This happens once a year (at one point between June 21-23). The phenomenon is called the summer solstice in the northern hemisphere and the winter solstice in the southern hemisphere.

But … why is this happening? How is it possible that the inclination with which the Sun’s rays reach the Earth’s surface is different depending on the hemisphere and the time of year? The answer is that the axis of rotation of the Earth that crosses it from North Pole to South Pole is inclined (around 23.5º) with respect to the plane in which the Earth orbits around the Sun.

Far from what many people think, the seasons do not occur due to the greater or lesser distance of our planet with respect to said star, but as a result of this inclination.

In this way, the hemisphere of the Earth that receives the solar rays more directly because it is more inclined towards it, will change as the earth makes the translational movement throughout the year.

2- The Tropic of Capricorn as the limit of climatic zones

The latitude line that the Tropic of Capricorn draws around the globe is also used as an imaginary reference to mark the lower limit of the tropical climate zone, the warm region of the planet.

In this way, in an associative way, those regions of the Earth that are included between the Tropic of Capricorn (23.5 ° south latitude) and the Tropic of Cancer (23.5 ° north latitude) receive the name of tropics. .

However, it is important to bear in mind that the climatic boundaries represented by both tropics are only an indicative limit. The Tropic of Capricorn, as well as that of Cancer, is a rigid reference to latitude. However, there are more factors that influence the climate and that would justify the presence of areas in the tropics that do not have the climatic characteristics normally associated with this region.

Finally, the Tropic of Capricorn also serves as a reference to mark the upper limit of the southern temperate climate zone of the planet. This region would be delimited, in turn, in its lower part by the Antarctic polar circle.

References

  1. Rosenberg, A. (December 21, 2015). Winter solstice: The shortest night of the year arrives, and the longest. The country. Recovered from elpais.com.
  2. Walker, A. and Batten, R. (December 23, 2000) The complete guide to the Tropic of Capricorn. The Independent. Recovered from theindependent.com.
  3. Esteban, C. (August 9, 2003) Astronomy in the Stone Age. Chaos and Science. Recovered from caosyciencia.com.
  4. Harper, K. (2004) A Student’s Guide to Earth Science: Words and Terms. Westport, United States: Greenwood Publishing Group .
  5. Mayhew, S. (2009) Dictionary of Geography. Oxford, UK: Oxford University Press.
  6. Pauli, R. E and Duarte, O. (2011) Tropical Fruits . Oxfordshire, UK: CAB International.
  7. NASA Space Place. What causes the seasons ?. Recovered from: spaceplace.nasa.gov.
  8. NOOA & NASA (2010) What’s a solstice? Recovered from: scijinks.jpl.nasa.gov.

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