Why the Sun's path varies
One year on Earth
A quick recap of the changing relationship between the Earth and the Sun can help us understand why the path of the Sun changes with the seasons.
Firstly, the Earth's 24 hour rotation makes the Sun appear to move across the sky every day. The Earth also orbits the Sun in an elliptical, although almost circular, path every 365.25 days, travelling along at around 67,000 mph! Additionally, the Earth's axis is tilted at an angle of 23.5 degrees compared to the plane of its orbit. It’s the combination of this tilt angle and Earth's orbit of the Sun that creates the seasons.
This means the Northern hemisphere is only angled towards the Sun for half of Earth’s orbit, creating summer there. During the other six months, the Southern Hemisphere is angled towards the Sun, creating winter in the Northern Hemisphere.
Firstly, the Earth's 24 hour rotation makes the Sun appear to move across the sky every day. The Earth also orbits the Sun in an elliptical, although almost circular, path every 365.25 days, travelling along at around 67,000 mph! Additionally, the Earth's axis is tilted at an angle of 23.5 degrees compared to the plane of its orbit. It’s the combination of this tilt angle and Earth's orbit of the Sun that creates the seasons.
This means the Northern hemisphere is only angled towards the Sun for half of Earth’s orbit, creating summer there. During the other six months, the Southern Hemisphere is angled towards the Sun, creating winter in the Northern Hemisphere.
Variations in length of day and night
It’s a common but incorrect belief that the seasons are caused by the distance the Earth is away from the Sun.
Variation in the Sun's path according to season
At the equator, day length is fairly consistent, but the further we travel north or south, the greater the seasonal variation in day length and temperature. At the poles there are periods of 24 hour daylight in summer and 24 hours of darkness in winter.
A Sun Compass will show you the path of the Sun at whatever latitude you happen to be.
A Sun Compass will show you the path of the Sun at whatever latitude you happen to be.
Lines of latitude
Our ancestors divided the Earth into an imaginary grid system, to help them navigate the oceans. Longitude lines run from pole to pole, latitude lines parallel to the equator. It's the latitude we're at that affects the height of the Sun in the sky. Latitude lines are numbered from zero at the equator to 90 degrees, north or south, at the poles.
The UK, where the Sun compass was developed, sits between 50 and 59 degrees north.
The UK, where the Sun compass was developed, sits between 50 and 59 degrees north.
A compass rarely points at the north pole
All data for the position of the Sun is calculated to true North – the axis around which the Earth spins. However, this is not the same as magnetic north - where a magnetic compass needle points. The difference between magnetic and true North is known as ‘Magnetic Declination'.
Because the magnetic pole drifts around, magnetic declination at any given point varies slowly over time. In some parts of the world it will be minimal (currently in the UK it’s less than 2 degrees west), in some places it can be as much as 40 or even 50 degrees. Small declinations can be ignored, while larger ones need to be accounted for. The Sun Compass allows us to do this.
You can find out the magnetic declination where you are, here: https://www.magnetic-declination.com
Because the magnetic pole drifts around, magnetic declination at any given point varies slowly over time. In some parts of the world it will be minimal (currently in the UK it’s less than 2 degrees west), in some places it can be as much as 40 or even 50 degrees. Small declinations can be ignored, while larger ones need to be accounted for. The Sun Compass allows us to do this.
You can find out the magnetic declination where you are, here: https://www.magnetic-declination.com
