1-Universe : It is the totality of matter, energy and space including thesolar system, the galaxies nd contents of the space between the galaxies.
2-Standard Time -It is a uniform time for places in approximately the same longitude.
3-Time Zone- Any of the 24 regions of the globe throughout which the same standard time is used.
4-Galaxy -These are composed of stars, dust and dark matter all held together by gravity.
5-Global Warming -It is the rise in the average temperatures of Earth’s atmosphere and oceans.
6-Environmental Crises -Global warming and poisoning of our soils, water and air are called environmental crises.
7-Prime Meridian- 0 degree longitude is called Prime Meridian or Greenwich Meridian.It passes through Greenwich , near London.
8-Core -It is the third and the thickest layer of the earth.
9-Mantle- The layer under the crust of the earth is called mantle.
10-Crust-The outer layer of the earth.
11-Latitudes-The horizontal circles that go round the earth.
12-Longitudes-The semi circles that connect north and south poles.
13-Big Bang -The sinle large explosion that created the universe.
14-Solar System-It is made up of all the planets that orbit the Sun.In addition to planets, the solar system also consists of moons,comets, asteroids, minor planets ,dust and gas.
15-Pangaea-It is a hypothetical continent from which present continents originated from the drift.
16-Gondwana Land-The break-up part of the Pangaea that consists of present South America, Africa,Madagascar,India, Arabia, Malaysia,East Indies,Australia and Antartica.
17-Grid -A pattern of square on a map that is formed of bi-section of two latitudes and longitudes.
18-Tethys Sea- A long shallow inland Sea that separated the blocks-Laurensia and Gondwana land.
19-Laurensia -The break-up part of Pangaea that consists of Present North America,Greenland and all of Eurasia North of Indian sub-continent.
20- Human beings arrived on earth about 1 lakh years ago.