Kepler’s laws: elliptical orbit with the Sun at a focusकेप्लर के नियम: सूर्य फोकस पर, दीर्घवृत्तीय कक्षा

NCERT Fig 7.1 · interactive diagram

Parts and their functions

• Elliptical orbit (दीर्घवृत्तीय कक्षा) — Law of orbits: every planet moves in an ellipse with the Sun at one focus.
• Sun at focus S (फोकस S पर सूर्य) — Not at the centre of the ellipse.
• Other focus S′ (दूसरा फोकस S′) — Empty — nothing sits there.
• Perihelion P (उपसौर P) — Nearest point: the planet moves fastest here.
• Aphelion A (अपसौर A) — Farthest point: slowest here. v_P r_P = v_A r_A.
• Semi-major axis a (अर्ध-दीर्घ अक्ष a) — Law of periods: T² ∝ a³.
• Area swept near P (P के पास प्रसर्पित क्षेत्रफल) — Law of areas: equal areas in equal times — a consequence of conservation of angular momentum.
• Equal area near A (A के पास समान क्षेत्रफल) — Same area, same time: the arc is shorter because the planet is slower.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 7.1. Report a mistake