earth tilting

[maximus]

does the earth tilt twice a year to give us summer and winter or is the earth on fixed non moving tilt

[bernardo]

No and yes respectively

[kags]

The earth's angle of tilt on its axis is approximately 23.5 degrees. There are slight variations on this tilt, but over many thousands of years, so we now see a slightly different part of the night sky than we did during the last ice age.

[headlesspets]

seasons have more to do with the nature of our orbit around the sun, as its elliptical

[manics_]

It is difficult to explain,. It is not the eliptical orbit of the earth that determins the seasons, it is the tilt of its axis.
Summer in the norther hemisphere is when the top of the axis is angled towards the sun, therefor the northern hemisphere is closer to the sun. And during the northern hemisphere's summer it is the souther hemispheres winter.
Hope this explains it. If not read this: http://www-istp.gsfc.nasa.gov/stargaze/Sseason.htm

[headlesspets]

oops - i had always been led to believe seasons were due to the orbit... i apologise profusely. coat has already been got.

[5x5]

Seasons are caused by the tilt of the Earth's axis of rotation - 23.4 degrees from the perpendicular. As you know, the Earth revolves around the Sun once each year. When the northern hemisphere is tilted toward the Sun this hemisphere experiences summer. Half a year later, the Earth is on the opposite side of the Sun with the northern hemisphere tilted away and experiencing winter. However, headlesspets should hang his/her coat back on the hook because there is an element of pertinence in the answer given. The Earth's orbit is somewhat elliptical and the distance between the Earth and the Sun varies over the course of the year. This effect does not cause seasons, but may well dictate their severity. Also bear in mind that solar events affect our weather too.