What are auroras?
People who live far enough north or far enough south can see
some spectacular sights and displays in the sky on clear nights. Beautiful,
large sheets of light seem to hang in the sky, rippling and wavering like
curtains on your window. The light flickers with shades of colours from frosty
white to pale green and pink. A crackling sound usually accompanies them, and
some people describe them as “giant fireworks display”.
In the northern hemisphere, these are called the aurora
borealis and in the southern they are “aurora australis”. The best displays of
the auroras can be seen around the Hudson Bay region of Canada, north Scotland,
southern parts of Sweden and Norway, South Australia and Srilanka, southern
parts of Sweden and Norway, South Australia and Srilanka.
It is believed that these lights are inside the earth’s
atmosphere, but what causes them comes through space from the sun. Edmund
Halley, the English astronomer proved way back in 1716, that there is a
relationship between the earth’s magnetic field and these lights.
The north and south magnetic poles of the earth are like the
ends of a big magnet. They attract the particles of energy from the sun. These
particles collide with other particles in the earth’s atmosphere and produce
sparks of shimmering, shivering lights. Although fusion activities are
continuously taking place in the sun which is a hot ball of fire, whenever
there are many sunspots seen on the sun, the number of charged particles coming
out from it is much larger. And more fireworks are coloured auroras are seen
when this happens.
What are asteroids?
Astronomers are always looking for new things and unusual
happenings around us. Observation and calculations have given way to many
discoveries.
The possibility of a planet’s presence between Mars and
Jupiter was suggested by J. Kepler and later by J.E.Bode which prompted astronomers
to search for it.
On January 1,1801, an Italian astronomer G. Piazzi sighted a
small planet a very tiny one with a diameter of only 600 miles. It was
discovered by H.Olbers. In time two more small planets were found out by other
astronomers.
When instead of one big planet, four small ones were
discovered, it was believed that one large planet could have been exploded or
broken and divided into these four. But after a gap of fifteen years, another astronomer
found one smaller planet, and the hunt for more such planets started all over
again. Since then the number of minor planets kept steadily increasing from 13
in 1850 to 1600 in 1950! It is now estimated that at least 100,000 planets some
of which probably no more than a few hundred yards across, are to be found in
this orbit. Minor planets are catalogued only when there are sufficient
observations to determine a reliable orbit. These planetary bodies revolving
around the sun mainly between the orbits of Mars and Jupiter are known collectively
as asteroids.
Some scientist believes that these asteroids were formed when
a satellite of Jupiter exploded in the distant past.
Reviewed by knowledge people creators
on
February 02, 2021
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