Navigation and science thumb|upright=1.3| A 1775 chart of Newfoundland, made from James Cook's Seven Years' War surveyings 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.
Navigation and science thumb|upright=1.3| A 1775 chart of Newfoundland, made from James Cook's Seven Years' War surveyings 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.