As Earth travels around the Sun, the planet is tilted to one side, by around 23.4°. So, as Earth maintains this constant orientation of its axis as we go around our elliptical orbit, it changes the angle of the Sun in our sky.
This diagram shows the celestial sphere and celestial equator, as they relate to Earth’s axes and the plane of the ecliptic around the Sun. (NASA)
MORE SCIENCE: What’s the difference between “astronomical spring” and “meteorological spring”?
Earth’s orbit is usually drawn with the ecliptic flat and the planet tilted, as shown above.
However, the relationship of our orbit to the seasons can be seen much easier if we shift our perspective, ever so slightly, as shown below.
This tilted view of Earth’s orbit around the Sun perfectly aligns the planet’s axis. A small yellow dot on each Earth represents the ‘subsolar’ point, where the Sun is directly overhead at that time, which is south of the equator for the December solstice, north of the equator for the June solstice, and directly on the equator for the equinoxes. (NASA/GSFC/Genna Duberstein/Scott Sutherland)
In the above view, Earth’s axis is straight up and down, and our orbit around the Sun is tilted to align with it.
From this perspective, when we are on the “left side” of the orbit, as presented above, the Sun is north of the celestial equator. With sunlight mostly focused on this hemisphere, it brings us warmer weather here in Canada.
When we are on the “right side” of the orbit, the Sun is south of the celestial equator. This focuses its light more on that hemisphere, which brings colder weather to us in the north.
