Cook first crossed the Antarctic Circle in January 1773

HMS Resolution, commanded by James Cook, made the first recorded crossing of the Antarctic Circle on 17 January 1773, during his second voyage in search of the supposed southern continent, Terra Australis. Cook’s journal, now in the British Library, records the moment at about a quarter past 11, adding that they were “undoubtedly the first and only ship that ever cross’d that line.”

Not quite the only one. Cook was sailing with a consort, HMS Adventure under Tobias Furneaux, and the State Library of South Australia’s account of the voyage says the ships crossed together in mid-January 1773. The two ships were separated shortly afterwards.

Cook kept pushing south over the next two summers. The record shows how close he came:

Date	Who	Milestone
17 Jan 1773	Cook (Resolution, Adventure)	First recorded crossing of the Antarctic Circle
Dec 1773	Cook (Resolution)	Crosses the circle again
30 Jan 1774	Cook (Resolution)	71°10′S, about 75 miles from the unseen mainland
27 Jan 1820	Bellingshausen	First sighting of the Antarctic mainland
20 Feb 1823	Weddell (Jane)	New farthest south, 74°15′S

At 71°10′S an ice field stopped him. Cook wrote that he would “not say it was impossible any where to get farther to the South,” but that he, “who had ambition not only to go farther than any one had been before, but as far as it was possible for man to go, was not sorry at meeting with this interruption.”

His conclusion was negative but decisive. By early 1774 the voyage had shown there was no habitable southern continent; whatever land lay south was locked behind ice. His farthest-south mark held for 49 years, and the land itself went unseen until 1820. The continent he missed is now governed under the 1959 Antarctic Treaty.