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 Notes on Earth in Space Chapter 1-1 The Earth in Space: 3rd planet from the sun The axis is an imaginary line on which the Earth rotates (spins) in space. The Earth's movement in space is what causes day and night and the seasons Earth moves in an elliptical orbit (oval-shaped) Day and Night: The rotation of the earth on its axis causes day and night The period of rotation is about 24 hours = 1 day The length of day and night changes because earth's axis is not straight up and down, it is tilted at an angle of 23 ° A Year on Earth: Earth revolves in an orbit around the sun. The period of revolution is about 365.26 days = 1 year After 4 years the .26 of a day each year causes an extra day to be added to the month of February, you will have 29 days that year (Leap Year)   Seasons on Earth: The seasons are causes by the tilt of Earth's axis and the revolution of the Earth around the sun The part of Earth having summer is not closer to the sun; it is tilted toward the sun. When the northern hemisphere is tilted toward the sun, it is experiencing summer, while the southern hemisphere will be tilted away and experiencing winter.   Summer Solstice: o Northern hemisphere is tilted toward the sun o Beginning of summer o longest day of the year; o Sun is at the highest point in the sky o June 20th or 21st   Winter Solstice: o Northern hemisphere is tilted away from the sun o Beginning of winter o shortest day of the year; o Sun is at the lowest point in the sky o December 21st or 22nd   Equinoxes: o neither the north pole or south pole is tilted toward the sun. o Equal length of day and night Vernal Equinox: o Beginning of spring o March 20th or 21st Autumnal Equinox: o Beginning of fall o September 22nd or 23rd The Magnetosphere: The Earth acts like a giant magnet in space Inner core of Earth made of the metals iron and nickel This acts like a magnetic bar that stretches from pole to pole This creates a force field that stretches into the space around the Earth The solar winds blow this magnetic field around, often changing its shape ¨Van Allen Radiation Belts: are the two doughnut shaped regions of the magnetosphere that trap charged particles ¨ Sometimes these charged particles crash into each other causing beautiful bands of light to form; these are called auroras ¨ Aurora Borealis is the band of light in North pole -      ·visible in the Northern Hemisphere ¨Aurora Australis is the band of light in the South pole -      ·Visible in the Southern Hemisphere