Fundaments of astronomy concepts for learners

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

The Milky Way is a galaxy where our sun belongs to it. It is a spiral-shaped galaxy. The position of our sun is the middle of one of its arms. The sun is about 30,000 light years from the centre of the galaxy. The diameter of the Milky Way is nearly 120,000 light years.

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  33^rd appearance was on February 9^th, 1986.