- The Sun's energy comes from nuclear fusion of hydrogen into helium. Light takes about 8 minutes and 20 seconds to reach the Earth.
- Planets in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Mercury is the smallest and nearest; Jupiter is the largest; Venus is the hottest (a runaway greenhouse) and the brightest planet; Saturn is famous for its rings.
- The Earth is the third planet; it is the only one known to support life. The Moon is its only natural satellite, and moonlight takes about 1.3 seconds to reach Earth.
- The Earth has one rotation (about 24 hours, giving day and night) and one revolution (about 365.25 days, giving the year and, with the axial tilt of 23.5°, the seasons).
- Important latitudes: the Equator (0°), the Tropic of Cancer (about 23.5° north, passing through India), the Tropic of Capricorn, and the Arctic and Antarctic Circles. The Prime Meridian (0° longitude) passes through Greenwich; the International Date Line runs roughly along 180°.
- Largest ocean: the Pacific; largest continent: Asia; smallest continent: Australia.
- Largest country by area: Russia; most populous countries: India and China (verify the latest ordering); largest desert: the Sahara (hot) / Antarctica (cold).
- Highest mountain: Mount Everest (about 8,849 metre, on the Nepal-China border); longest river: the Nile (the Amazon is the largest by volume); largest freshwater lake: Lake Superior; deepest ocean point: the Mariana Trench.
- Largest delta: the Sundarbans (Ganga-Brahmaputra); longest mountain range: the Andes.
- Area: about 3.28 million square kilometre, the seventh largest country. It lies wholly in the Northern Hemisphere.
- The Standard Meridian of India is 82.5° east (passing through Mirzapur, near Allahabad), and Indian Standard Time is 5 hours 30 minutes ahead of Greenwich.
- Northernmost to southernmost mainland: from the Himalayas to Kanyakumari; the southernmost point of Indian territory is Indira Point in the Andaman and Nicobar Islands.
- Longest river within India: the Ganga; longest river of peninsular (south) India: the Godavari (the "Dakshin Ganga"); the rivers that flow west into the Arabian Sea include the Narmada and Tapi (in rift valleys).
- Highest peak entirely within India: Kangchenjunga (Sikkim); the highest in the Indian-administered region is in the Karakoram.
- Largest State by area: Rajasthan; most populous State: Uttar Pradesh (verify the latest). The largest mangrove: the Sundarbans (West Bengal).
- The Western Ghats and the Eastern Himalaya are global biodiversity hotspots.
- India shares land borders with seven neighbours: Pakistan, Afghanistan (a small stretch in the Pakistan-occupied region), China, Nepal, Bhutan, Bangladesh and Myanmar.
- Boundary lines to know: the Radcliffe Line (India-Pakistan, drawn 1947), the Line of Control (in Jammu and Kashmir, with Pakistan), the McMahon Line (India-China, in the east), the Line of Actual Control (the effective India-China border), and the Durand Line (Afghanistan-Pakistan, relevant to regional security).
- Bangladesh has the longest land border with India; the maritime neighbours include Sri Lanka (separated by the Palk Strait) and the Maldives.
- Lines on a map: latitudes (parallels, east-west) and longitudes (meridians, north-south); isobars (equal pressure), isohyets (equal rainfall), contours (equal elevation).
- Atmospheric layers from the surface up: troposphere (weather), stratosphere (ozone layer), mesosphere, thermosphere (the ionosphere reflects radio waves), exosphere.
India's land borders are the operational geography of the central armed police forces: the Border Security Force on the Pakistan and Bangladesh frontiers, the Indo-Tibetan Border Police on the China frontier, the Sashastra Seema Bal on the Nepal and Bhutan borders, and the Assam Rifles on the Myanmar border. The boundary lines (Radcliffe, the Line of Control, the McMahon Line, the Line of Actual Control) are essential CAPF and interview knowledge, linked from Index and the security modules.
Q1The Standard Meridian of India, on which Indian Standard Time is based, is:
- A75° east
- B82.5° east
- C90° east
- D0°. (Answer: b.) Authored practice, not a verbatim PYQ.
Q2The boundary line between India and China in the eastern sector, drawn at the 1914 Simla Convention, is the:
- ARadcliffe Line
- BDurand Line
- CMcMahon Line
- DLine of Control. (Answer: c.) Authored practice, not a verbatim PYQ.