This answer is taken from a very good web-site
you might like to check out for yourself:
The Earth is tilted 23.5 degrees on its axis.
As it rotates on its axis, different regions on
Earth are tilted both towards and away from the
sun. This causes the sun's light and energy to
hit the different regions of the Earth at
different angles throughout the course of one
orbit, or one full year. This is what creates the
differences in the seasons and the annual warming
and cooling cycles of the Earth's Northern and
If the Earth's axis were parallel to the Sun
and not tilted, the sun would remain positioned
exactly halfway between the North and South Poles,
and there would be no seasonal changes on Earth.
Each area on Earth would maintain the same
relative climate and same amount of daylight
throughout the entire year. The reason our
planet maintains its relatively warm,
life-sustaining temperatures and climates is
because there is a very delicate balance within
its atmosphere, oceans and solid Earth.
Earth has a built-in, naturally-occurring
"force field" around it that creates and helps
maintain viable living conditions for its plant
and animal inhabitants. The atmosphere contains
greenhouse gases like carbon dioxide to keep the
Earth warm, and an ozone layer to protect the
Earth from harmful radiation.
Wind and ocean currents also help distribute
this heat around the globe, all within the Earth's
protective atmosphere. The Earth is unique in
its ability to create and maintain sustainable
living conditions because all of its systems and
influences are connected to each other.
Click Here to return to the search form.