That our seasons come from the tilt of Earth’s axis relative to its orbit of the Sun is easy to grasp, once you have used this Interactive. It shows the flow of seasons as the planet orbits the Sun, the angle of the Sun’s rays for a given location on Earth, how temperature varies at that location, and how the Sun’s path varies in the sky by season. Choose from 3 planets to see how their seasons reflect their unique tilts, or customize the tilt. What would “winter” be like if Earth had no tilt? This Interactive will show you.

1		Between the summer and winter solstices, how much does the altitude of the noon sun vary for observers in the United States? Need a Hint?
			A)	None; the Sun always rises due east and sets due west.
			B)	23.5 degrees
			C)	47 degrees
			D)	90 degrees

The 23.5 degree axial tilt of the Earth produces our familiar seasons, but the common public misconception is that our distance fromt the Sun also plays a role in this. Let's explore.

2		Which of these is NOT a correct explanation for the extra heating of summer for the United States? Need a Hint?
			A)	The Sun is much higher overhead in June than in December.
			B)	The Earth is closer to the Sun in June than in December.
			C)	The Sun's rays strike us more directly in June than in December.
			D)	The Sun is up longer in the summer than in the winter.

The 23.5 degree axial tilt of the Earth produces our familiar seasons, but other planets have tilts ranging from zero degrees to 98 degrees, with very different seasons than our own. In these questions, we will explore just how the tilt affects our own and other worlds.

3		Based on its axial tilt, which of these planets will show a seasonal cycle most like our own Earth's? Need a Hint?
			A)	Venus (tilt = 0 degrees)
			B)	Mars (tilt = 24 degrees)
			C)	Jupiter (tilt = 5 degrees)
			D)	Uranus (tilt = 98 degrees)

The 23.5 degree axial tilt of the Earth produces our familiar seasons, but other planets have tilts ranging from zero degrees to 98 degrees, with very different seasons than our own. Let's take this variation to the limit.

4		While several planets have tilts like our own, which jovian world has the most extreme tilt, with observable atmospheric seasonal changes now being studied closely for the first time? Need a Hint?
			A)	Jupiter (tilt = 5 degrees)
			B)	Saturn (tilt = 27 degrees)
			C)	Uranus (tilt = 98 degrees)
			D)	Neptune (tilt = 29 degrees)

Earlier we found that our orbit is so circular that distance change from Earth to Sun mattered little in our own seasons, but that is not always the case.

5		While the Earth's orbit is almost circular and little seasonal change arises here from our changing distance from the Sun, which of these planets would find its northern hemisphere summer solstice much colder than its southern hemisphere one, due to larger changes in perihelion and aphelion? Need a Hint?
			A)	Venus (eccentricity = .007)
			B)	Mars (eccentricity = .093)
			C)	Jupiter (eccentricity = .048)
			D)	Neptune (eccentricity = .010)