Some facts about
astronomy
The astronomical unit is the mean distance from the centre of
the sun to the centre of the earth.
Constellations appear to change their positions at different
times of night because the Earth revolves around the sun.
Mars is a red planet. Mercury is the closest planet and the
hottest planet. Venus is the brightest planet. Pluto is the farthest planet. Jupiter
is the biggest planet. Mercury and Venus do not have planets.
We see only one side of the moon all the time. Because the
period of rotation of the moon on its axis is equal to its period of revolution
around the Earth.
The earth and the moon are about the same distance from the
sun. Yet on average, the Earth is much warmer than the Moon. Because the
moon has almost no atmosphere.
Milky Way
Redshift of galaxies
The spectra of light from these galaxies show a frequency
shift towards the red known as the redshift. The shift indicates that the
galaxies are moving away. It is due to the Doppler Effect.
Constellations
One can note that stars within certain groups are so arranged
as to look like familiar objects or animals. These groups are called
constellations.
It is interesting to note that Vega is the brightest star in
the constellation Lyra. Vega would be the second star to have planets, the
first of course being the sun. There are 89 constellations; Hydra is the
largest of these.
Supernova
The collapsing core, during the death of a star, imparts so
much energy to the exterior of the star that it explodes with an increase in
its luminosity 10000 times or even more. This stage is referred to as a supernova explosion. Now the star is temporarily as bright as the whole Milky Way.
Richter scale
The magnitude of the earthquake is reported based on the Richter scale. In the Richter scale, the magnitude is dependent on the
amount of energy released and is measured by the amplitude of the largest wave
recorded on seismograms.
Above 5 is a Richter scale which is a damaging earthquake. While above
6 is the destructive earthquake. Above 7 is the major earthquake and above 8 in
Richter scale is the great earthquake.
Comets
Comets are the debris left over from the formation of the
outer planets. They orbit elliptically in the solar system.
A comet has a central core of icy material. When a comet
comes nearer to the sun, a portion of the gas leaves the head altogether
forming a tail, which always points away from the sun. The period of Halley’s
Comet is 76 years. Its 33rd appearance
was on February 9th, 1986.
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science