Obliquity is the angle that a planet's rotational axis makes with its orbital plane. In Earth's case, it is called the obliquity of the ecliptic. Obliquity gives a good indication of how extreme the seasons would be on a given world. Earth's obliquity of 23.5° means that at the summer solstice, the north pole tilts toward the Sun by 23.5°, and at the winter solstice, it tilts away by the same amount. This leads to fairly extreme temperature changes. Uranus, on the other hand, has an obliquity of about 97.86° – almost a right angle. This means that at its summer solstice, the north pole points almost directly at the Sun, and there is continuous daylight in most of the planet's northern hemisphere.
|Obliquities of planets in the solar system