What is the Tropic of Capricorn?

He Tropic of Capricorn Is the terrestrial parallel located at approximately 23.5 ° south latitude. It joins the most southerly points, that is to say, the zones located more to the south terrestrial on which the light of the Sun impinges zenith (completely vertical) once a year.

The tropic of Capricorn is, therefore, one of the multiple imaginary lines that cross the terrestrial globe in a horizontal (parallel) way. These lines of reference can be imagined as if they were belts that surround the Earth to different heights and that they become smaller as they approach the poles .

Tropic of Capricorn

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 line of reference (parallel) that is situated in the southern hemisphere of the earth. Specifically, this line is at a latitude of -23.5 ° (or 23.5 ° south) from the equator, bearing in mind that the latitude measures the distance to which a geographical point is to the equator ( Latitude 0).

While the Tropic of Capricorn is found 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 + 23.5 ° or 23.5 ° north.

Why countries pass the Tropic of Capricorn?

Imagine the tropic of Capricorn as a circle that crosses those areas south of the Earth on which the sun's rays can reach completely vertical. The imaginary line drawn would thus pass through all those territories that are situated at a latitude of 23.5 ° south.

Thus, the tropic of Capricorn crosses geographical points located in 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 is worth mentioning that Brazil is the only country in the world with territories located in geographical points that are going to be crossed by both the equator and the tropic of Capricorn.

Of course, the imaginary line drawn along Earth's latitude 23.5 not only crosses land. In its route, the Tropic of Capricorn also passes through three different oceans: Pacific Ocean, Atlantic Ocean and Indian Ocean

What 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 the whole of their territory below the 23.5 ° south latitude marked by the Tropic of Capricorn.

Interestingly, this is a very small figure compared to the 74 states that are totally above the Tropic of Cancer, in the Earth's northern hemisphere. This difference is due to a very simple reason: the percentage of firm land in the northern hemisphere is much higher than in the southern hemisphere.

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

  • Uruguay, the only country on the American continent located entirely south of the mark.
  • Swaziland and Lesotho, two very small countries in southern Africa.

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

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

The term tropic comes from the Greek ( Τροπικός ) And means"return". In the astronomical field, the word tropic is used to designate the latitudes located to the north (Tropic of Cancer) and to the south of the Earth (Tropic of Capricorn) on which the Sun can reach the zenith, that is to say, its greater height in the sky.

This means that, at any given time of the year, the Sun strikes completely perpendicular to the terrestrial surface marked by the situation of the Tropic of Capricorn. The phenomenon is called the solstice.

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

At present, this star is not in that constellation when once a year reaches its zenith in the southern hemisphere of the earth. Nevertheless, the traditional name has been maintained throughout the centuries and until today.

What is the purpose of the Capricorn trip?

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

Both sciences use the terrestrial zones delimited by Tropic of Capricorn (and by its equivalent in the Northern Hemisphere, the Tropic of Cancer) as reference to locate a series of natural phenomena. What event takes place on this land latitude?

1- The Tropic of Capricorn and the December Solstice

What relates to the Tropic of Capricorn with the December solstice?

In the southern hemisphere, where the Tropic of Capricorn is found, a solstice occurs once a year - usually sometime between 21 and 23 December. 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 which has been briefly spoken of earlier.

And is that the Tropic of Capricorn is the parallel or imaginary line that joins the terrestrial zones located to the south of the Earth whose surface can be reached once a year by the solar rays of completely vertical form. The moment 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 (at an angle of 90 ° to the ground) over the southern hemisphere zones found in the latitude marked by the Tropic of Capricorn. This particular position of the Earth with respect to the sun can be visualized using the analogy of a light bulb that hangs exactly above us, striking with its light vertically above 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 terrestrial surface.

Although the solstice may seem 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 sufficient.

For this reason, the experts say that this is a phenomenon of which the oldest civilizations had a record. In fact, there are authoritative voices who 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 inverse in each hemisphere. That is to say during the solstice that occurs at any given time between the 21st and 23rd of December every year:

  • In the southern hemisphere the Sun reaches the maximum height that will be seen in the sky throughout the year. The star comes to affect even 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.

Therefore, the solstice that occurs in December is known as the summer solstice in the southern hemisphere.

  • If the sun reaches its maximum height on the southern hemisphere, the northern hemisphere of the earth is positioned so that said star is at its minimum apparent height in the sky relative to it.

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

The same applies to the Tropic of Cancer, previously identified as the northern counterpart of the Tropic of Capricorn. The tropic of Cancer crosses the latitudes located farther north on which the Sun can influence zenith. This occurs once a year (at a point between 21 and 23 June). The phenomenon is called summer solstice in the northern hemisphere and winter solstice in the southern hemisphere.

Pe Ro... why does this happen? How is it possible that the inclination with which the rays of the Sun reaches the surface of the Earth is different according to the hemisphere and the time of the year? The answer is that the axis of rotation of the Earth that crosses it from North Pole to South Pole is inclined (around 23.5 °) to the plane in which the Earth orbits around the Sun.

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

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

2- The tropic of Capricorn as a limit of climatic zones

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

Thus, in an associative way, the tropics are called those regions of the Earth that lie between the Tropic of Capricorn (23'5 ° south latitude) and the Tropic of Cancer (23'5 ° north latitude) .

However, it is important to bear in mind that the climatic boundaries represented by both tropics are only a guiding limit. The Tropic of Capricorn, as well as that of Cancer, are 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 present 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 zone of the planet. This region would be delimited, in turn, in its inferior part by the Antarctic polar circle.


  1. Rosenberg, A. (December 21, 2015). Winter Solstice: The shortest night of the year arrives, and the longest. The country. Retrieved from elpais.com.
  2. Walker, A. and Batten, R. (December 23, 2000) The complete guide to the Tropic of Capricorn. The Independent. Retrieved 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. . The game of geometries under the sun . Master. UPC Barcelona. Available at: http://www.heliodon.net/downloads/El_juego_de_las_geometrias_bajo_el_sol.pdf. Recovered on December 27, 2017.
  8. NASA Space Place. What causes the seasons?. Retrieved from: spaceplace.nasa.gov.
  9. NOOA & NASA (2010) What's a solstice? Retrieved from: scijinks.jpl.nasa.gov.