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Polar Auroras
Polar auroras are caused by the solar wind. When the solar wind particles arrive near the
Earth, they are diverted toward the poles. This is why auroras are usually observed in polar
regions.
The arrival of the solar wind particles stimulates the particles in the Earth’s atmosphere.
This is what triggers the spectacular light show of the polar auroras. It is usually observed
as a green glow shimmering over the horizon.
Types of Polar Auroras
There are two types of polar auroras:
•the aurora borealis appears in the Northern Hemisphere
•the aurora australis appears in the Southern Hemisphere
Asteroids: A relatively small, inactive body, composed of rock, carbon or metal, which is
orbiting the Sun.
Comets: A relatively small, sometimes active object, which is composed of dirt and ices.
Comets are characterized by dust and gas tails when in proximity to the Sun. Far from the
Sun it is difficult to distinguish an asteroid from a comet.
Meteoroid
A small particle from an asteroid or comet orbiting the Sun.
Meteor
A meteoroid that is observed as it burns up in the Earth's atmosphere - a shooting star.
Meteorite
A meteoroid that survives its passage through the Earth's atmosphere and impacts the
Earth's surface.
Life of a Meteoroid
While passing though the Earth’s atmosphere, meteoroids undergo the following
transformations:
1.Their surfaces are heated.
2.Their surfaces are partially melted.
3.They become luminous.
4.They solidify as they slow down.