1. Hypothesis A :dependin of the position of the earth:
It's true.
The seasons are caused by a thing called "axial tilt", which basically means that the Earth
wobbles. It wobbles very slowly, mind you: but it does wobble.
When you spin a spinning top really fast, it starts out stable. Once the top has lost some energy,
it starts to wobble a bit, then some more, and more, until it's too unstable to keep spinning.
The Earth does pretty much the same thing: while it spins around the sun, it spins around itself,
and it wobbles. This causes one side of the Earth to be pointed at the sun at a better angle than
the other, and that side gets more sunlight.
More sunlight means more warmth, and that warmth is what causes summer. Likewise, the side
of the Earth that's at a shallower angle gets less sunlight, which means colder temperatures.
Currently (November 2012) the Northern hemisphere is pointed away from the sun, which
means less sunlight in a day, causing winter. The Southern hemisphere, on the other hand, is
experiencing summer.
Hypothesis B and C :because of the Earth rotation respect to the Sun:
The length of day also shortens as the Earth revolves away from a summer solstice
toward a fall equinox, and the pole stops pointing toward the Sun. On the equinox, the
length of time that the centerpoint of the Sun spends above and below the horizon is the
same for the entire planet (but length of day is actually longer than night because the
Sun is a disc, not a point; equal day and night is called equilux). After that, night
continues to lengthen until the pole is always in darkness.
So, getting back to the causes of seasons: when a pole points toward the Sun, its
hemisphere experiences summer, while the opposite hemisphere (with the pole in
darkness) has winter. The day of solstice is either the longest or shortest day of the year
for everywhere on the planet - but it's much longer or shorter at higher latitudes than
close to the equator.
What are the most common misconceptions about the causes of the seasons? That the
closeness of the Earth to the Sun is a cause, and that the solstice points match up with
perihelion and aphelion. Both are false. Find out why these misconceptions exist here.

2. Hypothesis D: depending of the distance from the Sun
What About Closeness to the Sun?
"Summer is when the Earth is close to the Sun, and winter is when the Earth is farther
away."
The above statement is false, and one of the most common misconceptions about the
causes of the seasons. Where does it come from?
The orbital path of the Earth around the Sun is an ellipse, rather
than a perfect circle. At some points along its path, the Earth is closer to the Sun, and at
other points farther away - that part is true. But often, diagrams that illustrate the ellipse
will exaggerate it to demonstrate their points, making it much more elongated than it
actually is.
From there, it's reasonable to assume that something close to a heat source will be
warmer than something far from it, and since summer is warm and winter is cold, the
seasons must be due to closeness to the Sun along the ellipse.
When we sit close to a heat source, we're warmer than when we sit farther away. But
stop and think about that for a moment too. Where are you warm? The parts that
directly face the heat source? What about the parts off to the side? Or do you have to
rotate back and forth a bit to warm up your sides and keep your front from getting too
toasty? The same thing happens for the Earth, as measured by the Sun's angle of
incidence, which depends on the Earth's axial tilt (see page 1).
Another common misconception is that the solstice points happen when the Earth is at
its closest to the Sun (perihelion) and at its farthest from the Sun (aphelion). This is also
false. The pattern of Earth's axial tilt doesn't match up quite so neatly with the orbital
ellipse.
So What Does Closeness to the Sun Do?
While the closeness of the Earth to the Sun is not a major cause of the seasons, it does
have some influence on the temperature ranges of whichever season is happening in
each hemisphere. The Earth is closer when the southern hemisphere is having summer,
and farther away when the southern hemisphere is having winter. Meanwhile, at the
same time, the northern hemisphere has winter when the Earth is close, and summer
when it's far. As a result, on average the southern hemisphere has much warmer
summers and much colder winters than the northern hemisphere.

3. Hypothesis E: depending of the amount of energy the Sun emit.
Our planet has an excellent source of energy: Sun. When solar radiation (i.e. the Sun’s
rays) reaches the Earth’s atmosphere, part of it is reflected back outwards and part of it
is absorbed by the atmosphere. The rest reaches the Earth’s surface, where once again,
part is reflected back and part is absorbed. The atmosphere and the surface (both land
and ocean) are heated, and thus emit infrared radiation out towards space. The overall
difference between incoming and outgoing energy is known as the net radiation or
radiation balance, and it can be stated for a region or for the planet as a whole.