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Source — Source: TH ///Category — GS Paper 3 ///Published — 2026-02-11 ///Exam — Both Prelims and Mains ///Tags — Quick Facts For Prelims, GS Paper - 3, General Science ///Source — Source: TH ///Category — GS Paper 3 ///Published — 2026-02-11 ///Exam — Both Prelims and Mains ///Tags — Quick Facts For Prelims, GS Paper - 3, General Science ///

Source: TH · GS Paper 3

Gravitational Control of Earth’s Motion

Gravity is the central force that binds all matter to Earth and acts as the centripetal force governing planetary orbits. Understanding Earth’s orbital speed, distance covered annually, and the absence of friction in space is essential for UPSC science and technology questions.

2026-02-11

Published

Source: TH

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Quiz Questions

Article

Key Facts and Data Points

Binding Force: Gravity holds humans, oceans, atmosphere and all life to Earth despite its motion through space.
Centripetal Action: Gravity keeps the Moon in orbit around Earth and Earth in orbit around the Sun.
Orbital Distance: Earth travels nearly 1 billion km in one revolution around the Sun.
Average Orbital Speed: Approximately 107,000 km per hour.
Absence of Friction: Space is a near‑vacuum; planetary motion continues without energy loss.
Rejection of Aether: The Michelson–Morley experiment (1887) disproved the existence of a resisting medium (aether).

Background and Context

Newton’s law of universal gravitation explains the attractive force between masses.
Kepler’s laws describe the elliptical nature of planetary orbits and the relationship between orbital period and distance.
Modern physics confirms that in the vacuum of space, only gravitational forces act significantly on large bodies.

Significance for India / Governance / Policy

Space Programme: Accurate knowledge of orbital mechanics is crucial for ISRO’s satellite launches, navigation (NAVIC), and interplanetary missions.
Science Education: Strengthening conceptual clarity in school curricula aligns with the National Education Policy’s emphasis on STEM.
International Collaboration: Understanding gravitational physics underpins participation in global projects like LIGO and gravitational wave research.

Related Constitutional / Legal Provisions

Article 48A of the Constitution encourages the State to protect the environment; understanding planetary dynamics aids climate modelling and satellite‑based monitoring.
Space Activities Act, 2022 (India) mandates adherence to international space law, which relies on precise orbital calculations.

References

Gravitational Waves (link provided in article)
Michelson–Morley Experiment – historical significance in physics.