The Universe Part-3

The elements nickel and ferrum are abundant in the forma- tion of Nife, the inner layer of the Earth. Nife is abbrevia- tion of Nickel and Ferrum (Iron).

There is an outer core and inner core below the mantle in the structure of the earth. The outer core is about 2260 Km thick (radius) and mostly composed of liquid iron and nickel. The Inner core is a hot dense ball of (mostly) Iron. It has a radius of about 1220 km.

Earth Day is celebrated on 22nd April every year to mark the birth Anniversary of Modern environmental movement in 1970. It was the first time celebrated in the year 1970.

Earth Day is celebrated on 22nd April every year to mark the birth Anniversary of Modern environmental movement in 1970. It was the first time celebrated in the year 1970.

Earth is tilted at an angle of 23 2 (Now 23.44°) on its axis. It rotates around on its axis with approximately a speed of 1037 miles per hour. Earth takes approximately 24 hours to complete one rotation on its axis.

According to a data published by European Space Agency, the Earth's magnetic field could flip. Something causes the movement of the molten core to change resulting in the reversal of the North and south magnetic poles. Earth is approximately 4.6 billion years old. The earlier en- vironment had an absence of free oxygen. Around 4 billion years ago water vapour present in the atmosphere condensed to form the hydrosphere. Around 1 billion year ago early aquatic animals like algae came into existence. They being autotrophs, started the process of photosynthesis which lead to the release of free oxygen in the atmosphere. In the upper layers of the atmosphere this free oxygen led to the formation of Ozone.

Aryabhatta was the first to explain that the rotation of the earth on its own axis accounts for the daily rising and setting of the sun. His works are compiled in Aryasiddhanta. Bhaskara-I was a proponent of Bhedabheda School of Vedanta Philosophy. Varahamihira's notable works include Brihat Samhita, Pancha Siddhantika.

Desert climate is also known as arid climate. The perfect climate for the desert is Tropical climate which is spread mostly between 15-30° latitude. There are four main geographical situations for the formation of desert -

(1) The presence of high air pressure near 30º latitude. Sahara and Australia desert fall under this climate.

(2) The western coastal side of continent found between

20°-30°latitude. Arizona desert, Mexican desert, Atacama desert, Namibian desert come under this climate.

(3) Death Valley (North America), Patagonian desert (Argentina) and Peruvian desert are the deserts found in mountains rainshadow region.

(4) The desert situated in the mid part of the Continents, far from the humid air. Gobi desert (China and Mongolia), Australian desert and Great basin desert (USA) come under this group.

The duration of the day on Earth is 23 hour, 56 minute 4 second and the tilt of its axis is 23°30'. The Planet Mars has nearly the same value as of Earth for its day duration is 24 hours, 37 minute 25 second and Mars tilt of the axis is 25 12 The duration of day and tilt of the axis of other planet is as follows-

Uranus duration of its day - 17 hours 14 minute the tilt of its axis - 97.77°

Neptune - duration of its day - 16 hour 6 minute the tilt of its axis - 28.3°

Saturn duration of its day - 10 hours 34 minute the tilt of its axis - 26.73°

The time taken by any planet to orbit around the sun depends on the distance between the Sun and the planet. The distance between the Sun and Mars is 227943824 km (228 million km), while the Earth is at a distance of 149598262 km (149.6 million km) from Sun and an orbital period of Earth is 365.256 days and that of Mars is 686.98 days. Thus statement (A) is false. The diameter of Mars is 6792 km while Earth's equatorial diameter is about 12756 km. Thus Reason (R) is correct.