Sky Matters: Sirius will be visible in the middle of March
It marks one of two days in the year when the nights and days are of roughly equal length across the world and when the Sun is directly above the Earth’s equator. In Ireland, “Spring” is generally regarded as starting on February 1st, in the UK it’s March 1st and in the US it coincides with the Spring Equinox! This lack of agreement on when Spring officially begins can cause some confusion – there’s an almost seven week difference – but in reality the definition is rather arbitrary.
Notwithstanding the debate about the onset of Spring, what if you were on another planet – would you still experience seasons? The answer is yes, but it varies widely. For example, both Jupiter and Venus have a very small tilt of their axis, a mere 3 degrees compared to 23.5 degrees for the Earth, and their orbit around the Sun is almost circular, meaning they are roughly at a constant distance and receive a constant amount of sunlight.
