how were the latitudes of the tropic of cancer, tropic of capricorn, Arctic circle, and Antarctic circle determined?
They were determined by people with sextants and chronometers measuring the height of the sun at noon.
DO a search for "The history of the sextant"
Arctic Circle: It is light 24 hours a day north of the Arctic Circle (66.5 degrees north) on the June Solstice. The sun at noon is 43 off zenith.
Tropic of Cancer: On the June Solstice the sun is directly overhead the Tropic of Cancer (23.5 degrees north latitude) at noon.
Equator: At the equator (zero degrees latitude), the day is always 12 hours long. At the equator, sun rises daily at 6 a.m. local time and sets at 6 p.m. local time. The sun at noon at the equator is 23.5 degrees off the zenith.
Tropic of Capricorn: The sun is low in the sky, at 47 degrees from zenith (23.5 plus 23.5).
Antarctic Circle: At the Antarctic Circle (66.5 degrees south), the sun makes the briefest of appearances at noon, peeking at the horizon and then instantaneously disappearing. All areas south of the Antarctic Circle are dark on the June Solstice.
South Pole: By June 21, it has been dark for three months at the South Pole (90 degrees south latitude. The sun set at the South Pole on The September Equinox.
September Equinox (approximately September 22-23)
This day begins fall in the Northern Hemisphere and spring in the Southern Hemisphere. There are twelve hours of daylight and twelve hours of darkness at all points on the earth’s surface on the two equinoxes. Sunrise is at 6 a.m. and sunset is at 6 p.m. local (solar) time for most points on the earth’s surface.
North Pole: The sun is on the horizon at the North Pole on the September Equinox in the morning. The sun sets at the North Pole at noon on the September Equinox and the North Pole remains dark until the March Equinox.
Arctic Circle: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 66.5 degrees off of the zenith or 23.5 degrees above the horizon.
Tropic of Cancer: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off of the zenith.
Equator: The sun is directly overhead the equator at noon on the equinox. On both equinoxes (which means "equal nights" in Latin), the sun is directly over the equator at noon.
Tropic of Capricorn: Experiences 12 hours of daylight and 12 hours of darkness. The sun is 23.5 degrees off of the zenith.
Antarctic Circle: Experiences 12 hours of daylight and 12 hours of darkness.
The latitudes of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle, and Antarctic Circle were determined through a combination of observations and calculations using astronomical tools and techniques. Here's a step-by-step explanation:
1. Astronomical Observations: Ancient civilizations, such as the Egyptians and Greeks, initially observed patterns in the movement of the Sun and stars to define certain latitudes on Earth.
2. Solstice Observations: Solstices are the points in the Earth's orbit when the Sun reaches its highest (summer solstice) or lowest (winter solstice) point in the sky. Ancient astronomers carefully observed the position of the Sun on these dates in different locations to determine their latitudes.
3. Gnomon and Shadow Measurements: Another technique involved using a vertical rod called a gnomon to measure the length and direction of the shadow it cast at different times of the day. By comparing these measurements from different locations, the difference in latitudes could be estimated.
4. Celestial Equator and Zenith: By observing the angle between the celestial equator (the imaginary line in the sky directly above the Earth's equator) and the zenith (the point directly overhead), astronomers could calculate their latitude.
5. Development of Instruments: As scientific knowledge and tools advanced, astronomers developed instruments like the astrolabe, sextant, and later, theodolites and GPS devices. These instruments allowed for more accurate and precise measurements of celestial bodies, aiding in the determination of latitudes.
6. Geodetic Surveys: In modern times, extensive geodetic surveys involving advanced satellite technology and global positioning systems (GPS) have been conducted to refine and establish the latitudes of different locations on Earth.
It is important to note that the determination of latitudes is an ongoing process, as Earth's movement and other factors can cause slight changes over time.
The latitudes of significant landmarks on Earth, such as the Tropic of Cancer, Tropic of Capricorn, Arctic Circle, and Antarctic Circle, were determined through a combination of observations, mathematical calculations, and the development of precise instruments. Here's an explanation of how each latitude was determined:
1. Tropic of Cancer: The Tropic of Cancer marks the northernmost latitude at which the Sun appears directly overhead at noon on the summer solstice (June 20 or 21). Its position was initially estimated by ancient astronomers who tracked the Sun's location at its highest point in the sky during summer solstice observations. Over time, with increasing astronomical knowledge and more advanced instruments like the celestial globe and astrolabe, the latitude of the Tropic of Cancer was refined through calculations based on the Earth's axial tilt of 23.5 degrees.
2. Tropic of Capricorn: The Tropic of Capricorn is the southernmost latitude where the Sun appears directly overhead at noon on the winter solstice (December 21 or 22). Similarly to the Tropic of Cancer, ancient astronomers and navigators made observations using instruments to track the Sun's highest point at noon during the winter solstice. By comparing and analyzing these observations with previous records, they were able to determine the latitude of the Tropic of Capricorn.
3. Arctic Circle: The Arctic Circle marks the parallel of latitude above which the phenomenon of the midnight sun occurs. This means that for at least one day a year (near the summer solstice), the Sun remains continuously above the horizon for 24 hours. The early determination of the Arctic Circle involved observing and documenting the longest day of the year in areas progressively closer to the North Pole. Explorers and scientists, using a combination of measurements, calculations, and astronomical observations, were able to establish the latitude where this phenomenon occurred and thus identified the Arctic Circle.
4. Antarctic Circle: The Antarctic Circle is the parallel of latitude below which the phenomenon of the midnight sun can be observed. Similarly to the Arctic Circle, the determination of the Antarctic Circle required observations of the longest day of the year in regions increasingly closer to the South Pole. By analyzing these observations, understanding the Earth's axial tilt, and using trigonometric calculations, scientists and explorers were able to establish the latitude of the Antarctic Circle.
In summary, the latitudes of these circles and tropics were determined through a combination of careful observations, mathematical calculations, and advancements in astronomy and instrumentation. Over time, the accuracy and precision of these measurements increased, resulting in their current values.