A terrella (Latin for "little earth") is a small magnetised model ball representing the Earth. It can be used to demonstrate the effect of earth's magnetic field on charged particles that come mainly from our sun. The small hollow sphere has a magnet inside it to represent the earth's magnetic field. When charged particles are directed at such a device in vacuum, the magnetic field lines trap the charged particles at the poles and equitorial planes to produce a glow akin to the aurora seen in the earth's polar regions due to solar radiation.

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