Grade 3 Science (NSO) : Earth and Universe

A look at the previous lessons on earth and universe :

Grade 2 Science (NSO) : Earth and universe

Weather and The Sky: Earth and Sky fundamentals

Earth’s Revolution

The motion around the sun along its orbit is called a revolution . The amount of time it takes for a single trip around the sun is called a period of revolution. The period for the Earth to revolve around the sun is 365.24 days or one year. The .24 days is why every four years February has 29 days.

There are 4 seasons in an year .In Autumn and Spring the northern and southern hemispheres are tilted equally toward the sun.In Summer the Earth is on the other side of the sun and the northern hemisphere is tilted  toward the sun and gets better sun rays. In winter the northern hemisphere is tilted away from the sun. That’s how we get seasons.

Earth’s orbit around the sun is slightly elliptical, Earth is actually slightly closer to the sun in the winter than it is in the summer.It is the tilt of Earth’s axis that causes the seasons.

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