Start at the 180th Meridian and work your way west. Enter the countries by the order you'd encounter them by doing this. If two countries share the same longitude, enter them in alphabetical order.
While online maps aren't known for precise accuracy, there are times when seconds count (ie slight errors made by surveyors). Although these may be approximations within an acceptable range of error, the precision is needed for differential purposes. Earth is defined by everything on this planet. Only states that have been recognised by over 50% of the U.N. fully included. Countries with significant support are included as bonuses. The Ilemi Triangle is considered Kenyan. The Hala'ib Triangle is considered Egyptian. Western Sahara is considered a no-man's-land. The Kuril islands are considered part of Russia. All of Arunachal Prudesh is considered part of India. Kashmir and the Spratly Islands are divided by how they are currently administered. Israeli borders follow the Blue Line, the 1949 Syrian-Israeli armistice line, and the 1967 borders of the West Bank and Gaza. Dependencies are not counted for this quiz, but territories that are integral parts of their home country do. For the debate of what's integral to Australia, I've only included inhabited territories.