On one day my friend Olivia has her birthday. Two days later it is the birthday of her elder twin, Oliver. Please explain.
Oliver was born on March 1 on a plane flying eastwards over the Pacific. A few seconds later the plane crosses the International Date Line, and Olivia is born. She is thus born on February 28, making her the ‘younger’ sister with a calendar birth date one day before her brother’s. On leap years, however, Olivia will celebrate her birthday two calendar days before her older twin.