Cook's 12 years sailing around the Pacific Ocean contributed much to Europeans' knowledge of the area.
Several islands, such as the Hawaiian group, were encountered for the first time by Europeans, and his more accurate navigational charting of large areas of the Pacific was a major achievement.
To create accurate maps, latitude and longitude must be accurately determined.
Navigators had been able to work out latitude accurately for centuries by measuring the angle of the sun or a star above the horizon with an instrument such as a backstaff or quadrant.
Longitude was more difficult to measure accurately because it requires precise knowledge of the time difference between points on the surface of the earth.
The Earth turns a full 360 degrees relative to the sun each day.
Thus longitude corresponds to time: 15 degrees every hour, or 1 degree every 4 minutes.
Cook gathered accurate longitude measurements during his first voyage from his navigational skills, with the help of astronomer Charles Green, and by using the newly published Nautical Almanac tables, via the lunar distance method – measuring the angular distance from the moon to either the sun during daytime or one of eight bright stars during night-time to determine the time at the Royal Observatory, Greenwich, and comparing that to his local time determined via the altitude of the sun, moon, or stars.

On his second voyage, Cook used the K1 chronometer made by Larcum Kendall, which was the shape of a large pocket watch, 5 inches (13 cm) in diameter.
It was a copy of the H4 clock made by John Harrison, which proved to be the first to keep accurate time at sea when used on the ship Deptford's journey to Jamaica in 1761–62.
He succeeded in circumnavigating the world on his first voyage without losing a single man to scurvy, an unusual accomplishment at the time.
He tested several preventive measures,  most importantly the frequent replenishment of fresh food.
For presenting a paper on this aspect of the voyage to the Royal Society he was presented with the Copley Medal in 1776.
Cook became the first European to have extensive contact with various people of the Pacific.
He correctly postulated a link among all the Pacific peoples, despite their being separated by great ocean stretches (see Malayo-Polynesian languages).
Cook theorised that Polynesians originated from Asia, which scientist Bryan Sykes later verified.
In New Zealand the coming of Cook is often used to signify the onset of the colonisation
which officially started more than 70 years after his crew became the second group of Europeans to visit that archipelago.

Cook carried several scientists on his voyages; they made significant observations and discoveries.
Two botanists, Joseph Banks and the Swede Daniel Solander, sailed on the first voyage.
The two collected over 3,000 plant species.
Banks subsequently strongly promoted British settlement of Australia, leading to the establishment of New South Wales as a penal settlement in 1788.
Artists also sailed on Cook's first voyage.
Sydney Parkinson was heavily involved in documenting the botanists' findings, completing 264 drawings before his death near the end of the voyage.
They were of immense scientific value to British botanists.
Cook's second expedition included William Hodges, who produced notable landscape paintings of Tahiti, Easter Island, and other locations.
Several officers who served under Cook went on to distinctive accomplishments.
William Bligh, Cook's sailing master, was given command of HMS Bounty in 1787 to sail to Tahiti and return with breadfruit.
Bligh became known for the mutiny of his crew, which resulted in his being set adrift in 1789.
He later became Governor of New South Wales, where he was the subject of another mutiny—the 1808 Rum Rebellion.
George Vancouver, one of Cook's midshipmen, led a voyage of exploration to the Pacific Coast of North America from 1791 to 1794.
In honour of Vancouver's former commander, his ship was named Discovery.
George Dixon, who sailed under Cook on his third expedition, later commanded his own.
Henry Ro
Cook's 12 years sailing around the Pacific Ocean contributed much to Europeans' knowledge of the area. Several islands, such as the Hawaiian group, were encountered for the first time by Europeans, and his more accurate navigational charting of large areas of the Pacific was a major achievement. To create accurate maps, latitude and longitude must be accurately determined. Navigators had been able to work out latitude accurately for centuries by measuring the angle of the sun or a star above the horizon with an instrument such as a backstaff or quadrant. Longitude was more difficult to measure accurately because it requires precise knowledge of the time difference between points on the surface of the earth. The Earth turns a full 360 degrees relative to the sun each day. Thus longitude corresponds to time: 15 degrees every hour, or 1 degree every 4 minutes. Cook gathered accurate longitude measurements during his first voyage from his navigational skills, with the help of astronomer Charles Green, and by using the newly published Nautical Almanac tables, via the lunar distance method – measuring the angular distance from the moon to either the sun during daytime or one of eight bright stars during night-time to determine the time at the Royal Observatory, Greenwich, and comparing that to his local time determined via the altitude of the sun, moon, or stars.
On his second voyage, Cook used the K1 chronometer made by Larcum Kendall, which was the shape of a large pocket watch, 5 inches (13 cm) in diameter. It was a copy of the H4 clock made by John Harrison, which proved to be the first to keep accurate time at sea when used on the ship Deptford's journey to Jamaica in 1761–62. He succeeded in circumnavigating the world on his first voyage without losing a single man to scurvy, an unusual accomplishment at the time. He tested several preventive measures,  most importantly the frequent replenishment of fresh food. For presenting a paper on this aspect of the voyage to the Royal Society he was presented with the Copley Medal in 1776. Cook became the first European to have extensive contact with various people of the Pacific. He correctly postulated a link among all the Pacific peoples, despite their being separated by great ocean stretches (see Malayo-Polynesian languages). Cook theorised that Polynesians originated from Asia, which scientist Bryan Sykes later verified. In New Zealand the coming of Cook is often used to signify the onset of the colonisation
which officially started more than 70 years after his crew became the second group of Europeans to visit that archipelago.
Cook carried several scientists on his voyages; they made significant observations and discoveries. Two botanists, Joseph Banks and the Swede Daniel Solander, sailed on the first voyage. The two collected over 3,000 plant species. Banks subsequently strongly promoted British settlement of Australia, leading to the establishment of New South Wales as a penal settlement in 1788. Artists also sailed on Cook's first voyage. Sydney Parkinson was heavily involved in documenting the botanists' findings, completing 264 drawings before his death near the end of the voyage. They were of immense scientific value to British botanists. Cook's second expedition included William Hodges, who produced notable landscape paintings of Tahiti, Easter Island, and other locations. Several officers who served under Cook went on to distinctive accomplishments. William Bligh, Cook's sailing master, was given command of HMS Bounty in 1787 to sail to Tahiti and return with breadfruit. Bligh became known for the mutiny of his crew, which resulted in his being set adrift in 1789. He later became Governor of New South Wales, where he was the subject of another mutiny—the 1808 Rum Rebellion. George Vancouver, one of Cook's midshipmen, led a voyage of exploration to the Pacific Coast of North America from 1791 to 1794. In honour of Vancouver's former commander, his ship was named Discovery. George Dixon, who sailed under Cook on his third expedition, later commanded his own. Henry Ro
James Cook