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- calendar year is roughly the time; Earth takes to travel once around our Sun – 365 days.
- our Earth actually takes 365.24219 (365¼) days to orbit our Sun -this is called a solar year.
- compensating for the missing 0.242 days (¼ day) -adds an extra day in February every fourth year – this is called leap year. (¼ day + ¼day + ¼day + ¼day = 1 day extra every four years)
- when measured by the stars – not our Sun, Earth takes 365.25636 days to go round our Sun – this is because our Sun also moves a little, relative to the stars; this is called sidereal year. (diagram)
- our Earth’s perihelion is the day its orbit brings it closest to the Sun – 3rd January, and (diagram)
- our Earth’s aphelion is the day it is furthest from the Sun – 4th July. (diagram)
- the planet with the shortest year is Mercury around the Sun in just 88 days.
- Neptune is the planet with the longest year – it takes 164.8 years to orbit the Sun.
Back to The Solar System page.