Tropic of Cancer

The Tropic of Cancer is a line on Earth.

It sits north of the middle of the world. The sun can be seen directly overhead there. This happens because the Earth tilts toward the sun.

This line stays in a hot and dry place. Many parts of it are in the Sahara Desert.

It passes through many lands and seas.

The line is not in the same spot forever. It moves slowly because the Earth wobbles. It is a special mark on our maps.

The Tropic of Cancer is a special line on Earth.

It is a circle of latitude in the north. This line marks the northernmost place where the Sun can be seen directly overhead. This happens on the June solstice. That is when the top half of Earth tilts most toward the Sun.

The line is north of the Equator. Its partner in the south is the Tropic of Capricorn.

The line moves slowly over time. This is because the Earth wobbles as it spins. In 1917, the line was at 23°27'N. By 2045, it will be at 23°26'N. This means it is drifting south.

Many places sit on this line. It passes through 17 countries and 8 bodies of water. It goes through the Sahara Desert. Most of this area is hot and dry. Summers are very hot. In the year 2000, over half the world's people lived north of this line.

One sign marks the line on a road in Mexico.

The Tropic of Cancer is a very special circle on our planet.

It is the northernmost place where the Sun can look directly overhead. This happens during the June solstice. At that time, the top half of Earth tilts most toward the Sun. This line is one of seven major circles of latitude on Earth maps. The Equator sits in the middle of our world. The Tropic of Cancer is north of the Equator. Its partner in the south is the Tropic of Capricorn.

This line is not stuck in one place. It moves very slowly because the Earth wobbles as it spins. This wobble is called axial precession. The tilt of the Earth changes over a long period of 41,000 years. Because of this, the Tropic of Cancer is drifting south. In 1917, the line was at exactly 23°27'N. By the year 2045, it will be at 23°26'N. It moves south by almost half an arcsecond every year.

The name of this line comes from a long time ago. In the last centuries BC, people saw the Sun in the constellation Cancer during the June solstice. Cancer is the Latin word for a crab. Today, the Sun is actually in the constellation Taurus during that time. The word "tropic" comes from a Greek word that means "turn." This is because the Sun appears to turn back at the solstices. This name describes how the Sun's path changes direction.

Many different places sit on this line. It passes through 17 countries and 8 bodies of water. It crosses the Sahara Desert, where it is often hot and dry. In the year 2000, more than half of all people lived north of this line. The line touches places like Mexico and China.

In Mexico, a sign once marked the line on a road. The highest mountain near the line is Yu Shan in Taiwan.

Life near the Tropic of Cancer can be very warm. Most places have two seasons. There is an extremely hot summer and a warm winter. Some areas have heavy rain, but many are quite dry. The line also has rules for pilots. To set a speed record, a flight must travel a distance at least as long as the Tropic of Cancer. This distance is about 40,075 kilometers. It is a huge path that circles the whole Earth.

The Tropic of Cancer is a significant circle of latitude on Earth. It marks the northernmost point where the Sun can appear directly overhead. This phenomenon occurs during the June solstice. At this time, the Northern Hemisphere reaches its maximum tilt toward the Sun. This line is one of seven major circles of latitude used on maps. These include the Equator, the two tropics, and the Arctic and Antarctic circles. The Poles are also considered circles, though they are degenerate circles.

The position of this line is determined by Earth's axial tilt. This tilt is the angle of Earth's rotation axis relative to the plane of its orbit. This plane is known as the ecliptic. The tilt is currently about 23.4 degrees. This specific value will remain valid for roughly one thousand years. The relationship between this tilt and the latitude circles is clearly shown in diagrams.

This circle is not a fixed location. It changes because of axial precession. Precession is a slow wobble in Earth's orientation. The axial tilt also varies over a 41,000-year period. This cycle moves the tilt between 22.1 and 24.5 degrees. Because of this wobble, the Tropic of Cancer is drifting southward. It moves at a rate of almost 0.468 arcseconds of latitude per year. In 1917, the line was at 23°27'N. By 2045, it will reach 23°26'N.

The name of the line has a historical connection to the stars. In the last centuries BC, the Sun was in the constellation Cancer during the June solstice. Cancer is the Latin word for crab. Due to precession, the Sun is now in the constellation Taurus during the solstice. The term "tropic" comes from the Greek word "tropē." This means a turn or a change in direction. It refers to how the Sun appears to turn back at the solstices.

Many diverse regions lie along this latitude. The line passes through 17 countries and eight water bodies. It starts at the prime meridian and moves eastward. It touches the northernmost point of Western Sahara. It crosses the Red Sea, the Indian Ocean, and the Pacific Ocean. It also passes through many Mexican states, including Sinaloa and Tamaulipas.

In Mexico, a sign once marked the line on a highway. This was the only intersection where the drift could be seen between 2005 and 2010.

The climate along the Tropic of Cancer is often hot and dry. Much of the land near the line is part of the Sahara Desert. Many areas experience two distinct seasons. There is an extremely hot summer and a warm winter. In some eastern areas, the climate is torrid monsoonal. These areas have a short wet season from June to September. Other places, like Hawaii or highland China, are cooler. Some coastal areas experience very heavy orographic rainfall. This type of rain is caused by air rising over mountains.

Geography and human life are also connected to this line. In the year 2000, more than half of the world's population lived north of the Tropic of Cancer. The highest mountain near the line is Yu Shan in Taiwan. While much of the region is hot, glaciers still exist nearby. The closest surviving glaciers are in the Himalayas and on Pico de Orizaba in Mexico. Finally, the line has importance in aviation. To set a round-the-world speed record, a flight must cover at least the length of the Tropic of Cancer. This distance is approximately 40,075 kilometers.