Happy Spring Equinox!
My plans this morning, as announced in the Telegraph, were to head to the top of a hill and catch the sun rising due east. Sadly, the air is cooler than its dewpoint… the humidity is greater than 100%… there is a low level of nimbostratus… however you want to put it: the weather is not very good and the visibility is terrible.
Had I been able to see the sun it would have risen due east. The vernal and autumnal equinoxes being the only two days of the year when the sun rises due east.
Something that you cannot notice on any individual day, but only by studying the sun’s rising position over the course of a year from the same location, is that its rising and setting positions are changing by more at this time of year than at any other time. Near the solstices the sunrise position slows its change to close to a ‘standstill’ (the name ‘solstice’ being derived from the Latin for ‘sun standing still’). At the equinoxes, in the UK, sunrise direction changes by nearly 5 degrees in a week.
The other thing that is changing very rapidly at this time of year are sunrise and sunset times, and therefore the length of the day. At the equinox everywhere on Earth shares a roughly equal day and night (the word comes from the Latin for ‘equal night’). Here in the UK, the day will be half an hour longer one week from now than it is today. This may be why we can sometimes feel ‘stuck’ in winter, but that when we feel the season turning and spring coming it is not a gradual shift, but more like a revolution. That said, it doesn’t feel very spring-like out there at the moment.
A good website for looking at sunrise and sunset times in the UK can be found here. The best one for checking the bearing (direction) of sunrise or sunset anywhere in the world is the US Naval Observatory.
Tags: equal day and night, equinox, solstices, standstill, sun, sunrise, vernal
