Shooting Stars: At night, when looking at the clear sky, one
may see streaks
of light shooting from one side of the vision to the other at an accelerated
rate. These are called shooting stars. Shootings stars are in fact dust
particles which collide with our atmosphere at rapid speeds and the
friction causes the dust to burn up. Shooting stars may be
seen on any clear night but is best observed during a meteor showers.
These dust particles helps Earth gain around 550 tonnes of weight every day.
Meteorites are chunks of space debris that hit the Earth. So far,
no humans have been known to have been killed by meteorites though
astronomers believe that a meteorite caused the mass extinction of dinosaur 65
million years ago when it hit Central America, the meteorite is
believed to have measured some 10 km in width.
Comets are essentially chunks of ice characterised by their tail of
gas and dust which erupts from them as they are nearing the sun. Their tails always points away from the sun, no matter what
distance awau from the sun it
flies. One of the most famous comets is the Halley’s comet (first
recorded by the Chinese is 240BC) which in 1986, a probe called Giotto flew
into and took photos of its 16km long nucleus. Halley’s comet flies past
earth every 76 years.
Asteroids are giant boulders floating around in space, most of
which are confined within its elliptical orbit between Mars and Jupiter,
collectively known as the ‘asteroid belt'. About 200 asteroids with
diameters more than 100km and thousands with smaller diameters exist. Many
scientists believe that asteroids are the shattered remnants of planets
which increased in
numbers as the asteroids smashed into each other and
shattered themselves even more. In the even that an asteroid such as ‘Ida'
(52km long) smashed into the Earth, there would be mass extinctions which
would leave only bacteria alive, waves of fire would engulf the terrain
destroying everything in its path including cities and forests, there would
be tidal waves, earthquakes and massive floods of lava. The dust kicked up
by all of the commotion would blot out the sunlight for decades. Fortunately
Ida is in the asteroid belt 290 million km away from us, although there are
many more large asteroids at closer to us.