How far is the Tropic of Cancer from the equator?

Answer 1

According to the Fédération Aéronautique Internationale's rules, for a flight to compete for a round-the-world speed record, it must cover a distance no less than the length of the Tropic of Cancer as well as cross all meridians and end on the same airfield where it started. This length is set to be 36787.559 kilometres - a number implying a precision which does not exist, considering the variations of the tropic described above. From: http://en.wikipedia.org/wiki/Tropic_of_Cancer

Answer 2

The circumference or length of Tropic of Cancer and Capricorn.

This depends on the time, date, ellipsoid of revolution or reference ellipsoid used, and whether the calculations are made using True or Mean obliquity of the ecliptic.

All at UT 00 Hours, 00 Minutes, 00 Seconds:

1 July 2018 calculated in True obliquity (IAU 2000B nutation series): 23° 26' 06.663" N / S, circumference (WGS84 ellipsoid) 36,788.734 km or 22,859.460 miles or 19,864.327 nautical miles.
Area of the tropics as defined by the Tropic of Cancer and Tropic of Capricorn calculated in the WGS84 ellipsoid 202,094,844.014964 square km or 78,029,255.504476 square miles.
Distance from latitude 23° 26' 06.663" North to latitude 23° 26' 06.663" South is 5,185.466 km or 3,222.099 miles or 2,799.928 nautical miles.

1 July 2018 calculated in Mean obliquity (Lasker): 23° 26' 12.790" N / S, circumference (WGS84 ellipsoid) 36,788.263 km or 22,859.167 miles or 19,864.073 nautical miles.

1 July 2018 the WGS84 ellipsoidal difference in latitude, i.e. due north-south between True obliquity (IAU 2000B nutation series) 23° 26' 06.663" N / S and Mean obliquity (Lasker) 23° 26' 12.790" N / S is 188.490598834 metres/meters or 618 feet.

1 January 2019 calculated in True obliquity (IAU 2000B nutation series): 23° 26' 07.842" N / S, circumference (WGS84 ellipsoid) 36,788.643 km or 22,859.403 miles or 19,864.278 nautical miles.
Area of the tropics as defined by the Tropic of Cancer and Tropic of Capricorn calculated in the WGS84 ellipsoid 202,097,512.715759 square km or 78,030,285.895614 square miles.
Distance from latitude 23° 26' 07.842" North to latitude 23° 26' 07.842" South is 5,185.538 km or 3,222.144 miles or 2,799.967 nautical miles.

1 January 2019 calculated in Mean obliquity (Lasker): 23° 26' 12.555" N / S, circumference (WGS84 ellipsoid) 36,788.281 km or 22,859.178 miles or 19,864.083 nautical miles.

1 January 2019 the WGS84 ellipsoidal difference in latitude, i.e. due north-south between True obliquity (IAU 2000B nutation series) 23° 26' 07.842" N / S and Mean obliquity (Lasker) 23° 26' 12.555" N / S is 144.990404312 metres/meters or 476 feet.

1 July 2019 calculated in True obliquity (IAU 2000B nutation series): 23° 26' 08.935" N / S, circumference (WGS84 ellipsoid) 36,788.559 km or 22,859.351 miles or 19,864.233 nautical miles.
Area of the tropics as defined by the Tropic of Cancer and Tropic of Capricorn calculated in the WGS84 ellipsoid 202,099,986.747279 square km or 78,031,241.124524 square miles.
Distance from latitude 23° 26' 08.935" North to latitude 23° 26' 08.935" South is 5,185.606 km or 3,222.186 miles or 2,800.033 nautical miles.

1 July 2019 calculated in Mean obliquity (Laskar): 23° 26' 12.323" N / S, , circumference (WGS84 ellipsoid) 36,788.299 km or 22,859.189 miles or 19,864.092 nautical miles.

1 July 2019 the WGS84 ellipsoidal difference in latitude, i.e. due north-south between True obliquity (IAU 2000B nutation series) 23° 26' 08.935" N / S and Mean obliquity (Lasker) 23° 26' 12.323" N / S is 104.228198033 metres/meters or 342 feet.

To calculate the latitudes I used the PHP Science Labs website, Obliquity of the Ecliptic, Nutation in Obliquity and Latitudes of the Arctic/Antarctic Circles (for True using the IAU 2000B series) http://www.neoprogrammics.com/obliquity_of_the_ecliptic/
Distances calculated using Charles Karney's Online rhumb line calculations using the RhumbSolve utility https://geographiclib.sourceforge.io/cgi-bin/RhumbSolve : "RhumbSolve is accurate to about 15 nanometers (for the WGS84 ellipsoid)" or 0.000015 of a millimetre/millimeter or 0.000059 of an inch. In emails to me from Charles Karney: "The accuracy of 15 nanometers that I quote is for paths up to half-way round the earth." "The accuracy for the Airy [1830] ellipsoid will be (very nearly) the same as for the WGS84 ellipsoid because the parameters are roughly the same." On RhumbSolve online: "RhumbSolve performs rhumb line calculations". "The path with a constant heading between two points on the ellipsoid at (lat1, lon1) and (lat2, lon2) is called the rhumb line (or loxodrome)". "NOTE: the rhumb line is not the shortest path between two points; that is the geodesic and it is calculated by GeodSolve."
Areas calculated in the WGS84 ellipsoid, using Charles Karney's "geodesic polygon calculations using the Planimeter utility": https://geographiclib.sourceforge.io/cgi-bin/Planimeter "The result for the area is accurate to about 0.1 m² per vertex."

From this website: http://lakewoodhiker.blogspot.co.uk/search?q=Arctic+Circle
"My name is John Fegyveresi and as of this summer (2015), I am now working full time as an honest-to-goodness scientist up at the Cold Regions Research and Engineering Lab (US Army Corps of Engineers) in Hanover, NH. I just recently finished up my graduate school work at Penn State University studying glaciology, ice cores and climate change": "If I were to ask what the latitude of the Arctic Circle is, most would answer by saying either 66°30′, or maybe even 66°33′ to be more exact. Well...it turns out that it's not a simple thing to answer." "Thankfully, we can answer this question with a very handy-dandy on-line calculation tool found here:
http://www.neoprogrammics.com/obliquity_of_the_ecliptic/". "This tool exactly calculates the angle of the ecliptic of obliquity and will spit out a very precise location of the Arctic Circle on any given date. So let's plug in some numbers and see what it says." "Turns out that there is a very tiny natural "wobble" to the progression off the Earth's obliquity called the "Nutation". In other words, as the Arctic circle drifts Northward, there is a very slight sinusoidal wave component to it. This means over several years it will drift North, then back South, then back North...all while generally trending North. This will happen until the tilt reaches a minimum of about 21.1° around the year 11,800, at which time the Arctic Circle will finally start trending back South. I played around with various dates using the calculation tool with both the Laskar and the IAU methods, and just as I suspected, the Laskar method just averages out the natural wobble and calculates the approximate "mean" of the latitude line. So, in a nutshell, the precise Arctic Circle is the IAU-determined value, but the mean is still pretty close and an easier way to visualize it."

Jürgen Giesen on his website's Obliquity Applet page: "The obliquity of the ecliptic is the angle of inclination of the Earth's axis of rotation. True obliquity takes into account the nutation of the Earth's axis. Nutation is a periodic oscillation of the rotational axis of the Earth around its mean position. Nutation is due mainly to the action of the Moon. The most important term has a period of 18.6 years."

Position and Time document: "OBLIQUITY OF THE ECLIPTIC (SYMBOL ε) is the angle at which the celestial equator is tilted with respect to the ecliptic; it is equal to the tilt of the Earth's axis from the perpendicular to the plane of its orbit. The obliquity of the ecliptic varies slightly with time due to the effects of nutation and the gravitational pulls of the planets on the Earth. Nutation causes a variation of up to 9".2 from the mean value every 18.6 years, while planetary precession is currently causing the mean value of the obliquity to decrease by 0".47 per year. On 2000 January 1 the obliquity was 23° 26' 21", and on 2050 January 1 it will be 23° 25' 58"."

True obliquity of the ecliptic is used to calculate the latitudes of the Arctic Circle, sent to me from the National Land Survey of Finland, the Finnish Geodetic Institute, who calculated the latitudes sent to me, for every ten days, for the years 2000-2049.
From the GIT Barents website, though it now only available using the Wayback Machine: https://web.archive.org/web/20140902210927/http://www.gitbarents.com:80/ArcticCircle.aspx
"As a natural phenomenon, the Arctic Circle is quite analogous to the Antarctic Circle, Equator and the Tropics of Capricorn and Cancer on our globe. All these phenomena are based on the same astronomical factors: The earth's orbital plane around the sun, the earth's own axis of rotation and the tilt angle of that axis in relation to the orbital plane. The motion wave of the Arctic Circle is the sum of component motions that have different frequencies. The most significant of these are the two-week period, half year period, 18.6 year period and 41 000 year period." "In the 18.6 year period, the circle has in 2006 passed the peak of the motion wave: Until the year 2015 the Arctic Circle will travel again 700 metres to the north, and after that it will continue to the south about 450 metres during the following nine years. Depending on the phase of the motion, the Arctic Circle can move over three metres a day and over 100 metres a year!"
Therefore one can state, that the Tropic of Capricorn has in 2006 passed the peak of the motion wave. Until the year 2015 the Tropic of Capricorn will travel again about 700 metres/meters or 766 yards or 2297 feet to the north, and after that it will continue to the south about 450 metres/meters or 492 yards or 1476 feet during the following nine years. Depending on the phase of the motion, the Tropic of Capricorn can move about three metres/meters a day or 3 yards 10 inches or 9 feet 10 inches and over 100 metres/meters or 109 yards or 328 feet a year. Furthermore one can state, that the Tropic of Cancer has in 2006 passed the peak of the motion wave. Until the year 2015 the Tropic of Cancer will travel again about 700 metres/meters or 766 yards or 2297 feet to the south, and after that it will continue to the north about 450 metres or 492 yards or 1476 feet during the following nine years. Depending on the phase of the motion, the Tropic of Cancer can move about three metres/meters or 3 yards 10 inches or 9 feet 10 inches a day and over 100 metres/meters or 109 yards or 328 feet a year.
In my opinion true obliquity of the ecliptic should be used. Since true obliquity is the actual, hence "true". Mean obliquity of the ecliptic is only obviously the mean, and is in my opinion, just for the convenience of humans. Since when for example using mean obliquity of the ecliptic, the Tropic of Cancer will supposedly only move south, and the Tropic of Capricorn only north, both at an equal, regular rate, for the about next 10,000 years. Which makes for far easier calculations of the latitudes. Mean is just that, only the mean movement, for 2016 a leap year, a movement of 14.43 metres/meters or 15 yards 2 feet 4 inches or 47 feet 4 inches, and for 2017, 14.39 metres/meters or 15 yards 2 feet 2½ inches or 47 feet 2½ inches, for both 3.94 centimetres/centimeters or 1.55 inches a day, distances are only due south for Tropic of Cancer, and only due north for the Tropic of Capricorn, calculated in WGS84. They are calculated from the mean or average speed of movement either only south (Cancer) or only north (Capricorn) over a 18.6 year cycle, and therefore the same mean or average speed of movement only south (Cancer) or only north (Capricorn) is applied to a year. Approximately every 18.6 years, the angles of mean obliquity and true obliquity match, and therefore the calculated latitudes match, next at least on 2 April 2020. For example, using the true obliquity example stated above, for the Tropic of Cancer: Approximately 700 metres/meters to the south, and then approximately 450 metres/meters to the north. 700 metres/meters south - 450 metres/meters north = 250 metres/meters farther south over a 18.6 year cycle. Mean obliquity an average of 14.40 metres/meters a year (leap and ordinary) x 18.6 years = 267.84 metres/meters farther south over a 18.6 year cycle, compared to approximately 250 metres/meters farther south for true obliquity. The difference is because, the quoted distances for true obliquity are only approximate.
The Tropic of Cancer is actually moving mostly south but sometimes north, for about the next 10,000 years, and it moves in a seemingly random, unpredictable manner (true obliquity of the ecliptic). Of course this means, that the Tropic of Capricorn is moving mostly north, but sometimes south, for about the next 10,000 years.
The Swedish National Land Survey or Landmäteriet website has a Arctic Circle latitude calculator, that calculates in both mean and true obliquity of the ecliptic. However it only gives two latitudes for each year, one for mean obliquity, and one for true obliquity.

Answer 3

It is about 2600 km, or about 1600 miles North of the equator. It represents the most northerly position where the sun appears overhead in June of each year. It is just more than 23 degrees north of the equator.

Answer 4

2500 miles... my textbook said so lol ;D

Answer 5

About 2,607 km.