Kate Humble and Dr. Helen Czerski follow the Earth's voyage around the sun for one complete orbit;, they travel from July to the December solstice, experiencing spectacular weather and the largest tides on Earth; to show how the Earth's orbit affects daily life, Helen jumps out of an airplane and Kate briefly becomes the fastest driver on the planet.

Kate Humble and Dr Helen Czerski cover the January to March equinox. Kate gets closer to the Sun than she has ever been before, while Helen visits a place that gets some of the biggest and fastest snowstorms on Earth.

Presenters Kate Humble and Dr Helen Czerski examine the March equinox to the end of June. Kate is in the Arctic at a place where spring arrives with a bang, whilst Helen chases a tornado to show how the Earth's angle of tilt creates the most extreme weather on the planet.