Comets and Asteroids
Along with the Sun, the planets and their moons, several other
objects made up of small pieces of rock, metal and ice are
also a part of the solar system. These objects are asteroids,
comets and meteors.
Quick Q’s:
1. What are sungrazers?
Some comets crash
into the Sun or get
so close to it that they
break up into tiny
pieces. Such comets
are called sungrazers.
2. Where are asteroids
found in the solar
system?
Most asteroids are
found in a region
between Mars and
Jupiter, which is known
as the asteroid belt.
3. Do asteroids have
moons?
The asteroid Ida has
a tiny moon, Dactyl.
This was discovered
by the spacecraft
Galileo in 1993.
4. When will Halley’s
Comet be seen again?
Halley’s Comet takes
about 76 years to
complete one orbit
around the Sun, so
it is expected to be
seen again in 2061.
5. Why does a comet
have a tail?
A comet is made up
of ice and other
material. As it nears
the Sun, these materials
heat up. Solar wind and
pressure from the Sun’s
radiation push them
outwards to form a tail
that always points away
from the Sun.
Q Are asteroids planets?
A When the solar system was formed,
some fragments of rock were left spinning in
space. These huge space rocks that orbit the
Sun are called asteroids. Like other planets,
asteroids are also made of metals like iron
and have moons. Some of them are called
minor planets.
Q Are asteroids dangerous?
A An asteroid can be thrown off its orbit
by the gravity of larger planets, or if it comes
too close to another asteroid. Once it is off its
orbit, the stray asteroid often strikes the
surface of other planets and moons. This
causes widespread destruction and creates
huge craters. In fact, some scientists think
that an asteroid struck Earth about
65 million years ago, causing the extinction
of the dinosaurs.
Q Are shooting stars really stars?
A Shooting stars are actually pieces of
burning rock called meteors. A meteor is
formed when a piece of debris in the solar
system, called a meteoroid, enters the Earth’s
atmosphere. As the meteor rubs against the air
in the Earth’s atmosphere, it gets hotter and
hotter until it burns up in a streak of light.
Asteroid belt
Most of the asteroids in our solar system can be found
in a belt between the orbits of Mars and Jupiter.
A meteor
We can see a meteor without a telescope when it
enters the Earth’s atmosphere. Sometimes, a number of
meteors are seen within a very short period of time.
They leave a streak of light, which disappears very
quickly. This is called a ‘meteor shower’, also known
as ‘meteor storm’.
Earth
Mercury
Venus
Jupiter
Mars
Q How is a comet’s tail formed?
A A comet is a mixture of ice, gas and
dust. Like asteroids, they too travel around
the Sun. As a comet nears the Sun, the ice
on its surface melts and a jet of gas and dust
particles is released to form a tail. Comet
tails can be as long as 10 million kilometres
(6.2 million miles).
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