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Many students who like the night sky assume the astronomy olympiad needs a telescope and years of star-gazing. It mostly needs Class 11 and 12 physics and mathematics, applied to the sky. This post explains the stages of India's astronomy olympiad, using the official 2026-27 documents, works two problems of the kind NSEA asks, and ends with a study routine.
The main sources are the HBCSE brochure for the 2026-27 science olympiads and the IAPT NSE 2026 student brochure. Rules are revised each year, so read the current brochure before relying on any number here.
What are the stages of the astronomy olympiad?
HBCSE, part of the Tata Institute of Fundamental Research, is the nodal centre. The programme has five stages:
NSEA (National Standard Examination in Astronomy), conducted by the Indian Association of Physics Teachers (IAPT) at schools across India.
INAO (Indian National Astronomy Olympiad), run by HBCSE. Its tentative schedule puts INAO 2027 on 30 January 2027.
OCSC (Orientation-cum-Selection Camp) at HBCSE, with theory, data analysis and night-sky observation.
Pre-departure training for the selected team.
IOAA (International Olympiad on Astronomy and Astrophysics), with a team of five students.
Who is eligible for NSEA 2026?
The brochure lists these conditions, among others:
Born between 1 July 2007 and 30 June 2012.
Studying in Class 10, 11 or 12 at enrolment, and not finishing Class 12 before 30 November 2026.
Eligible to hold an Indian passport, and studying in India since 30 November 2024 or earlier.
Not appearing in NSEJS 2026, the junior olympiad.
NSEA 2026 is on Saturday, 21 November 2026, from 2:30 pm to 4:30 pm, in English and Hindi. Enrolment ran from 21 August to 14 September 2026 through schools or the IAPT website. If you missed it, plan now for the 2027 cycle.
What does the NSEA paper look like?
Per the brochure, the paper has two parts:
Part A: 48 multiple-choice questions with one correct option, +3 for correct and −1 for incorrect.
Part B: 12 questions of 6 marks each with one or more correct options. You get credit only if you mark all the correct options and no wrong one.
That makes a maximum of 48 × 3 + 12 × 6 = 144 + 72 = 216 marks.
The HBCSE syllabus page says NSEA covers Class 12 level physics and mathematics, plus elementary astronomy: the solar system, phases of the Moon, seasons, eclipses, tides, stars and galaxies, the night sky, telescopes and the history of astronomy. It adds that in-depth astronomy knowledge is not required.
How do you qualify for INAO?
Students are split into Group A (in Class 12 on 30 November 2026) and Group B (Class 11 or below). For astronomy, the target is at least 250 students from each group. Key rules include:
Minimum Admissible Score (MAS): 50% of the average of the top ten scores, rounded down.
Merit Index (MI): 80% of that average, rounded down. Anyone at or above MI qualifies automatically.
A state-wise quota and a supernumerary quota so that at least 20% of those selected are female, both subject to MAS.
Example from the brochure. If the top ten average is 92.3, MAS = 46.15, rounded down to 46, and MI = 73.84, rounded down to 73.
Worked example: Kepler's third law
Problem. Mars orbits the Sun at an average distance of 1.52 AU. Estimate its orbital period.
For bodies orbiting the Sun, Kepler's third law in convenient units is T² = a³, with T in years and a in astronomical units (AU). This follows from Newton's gravitation, and Earth (a = 1 AU, T = 1 year) fixes the constant.
a³ = 1.52³ = 3.51.
T = √3.51 ≈ 1.87 years.
Worked example: how often Mars comes close
Problem. How often does Earth overtake Mars, so that Mars is again opposite the Sun in our sky?
Earth goes round at 1/1 orbit per year, Mars at 1/1.87 orbits per year.
Earth gains on Mars at 1 − 1/1.87 = 1 − 0.535 = 0.465 orbits per year.
One full lap takes 1/0.465 ≈ 2.15 years. This is the synodic period: oppositions of Mars come roughly every two years and two months.
These two ideas, scaling laws and relative angular speed, appear again and again. Our post on gravitation and satellite problems builds the physics behind them.
Common mistakes
Reading popular astronomy only. Facts help, but NSEA mostly tests calculation.
Mixing units. Keep AU and years together, or SI units together. Do not mix them.
Over-marking in Part B. One wrong option loses the whole 6 marks.
Ignoring the sky. Know the bright stars, common constellations and why the Moon has phases.
A study routine for the year
Weekly: two sessions of Class 11 mechanics and gravitation, one of maths (trigonometry, vectors, calculus), and one of astronomy reading.
Monthly: a past NSEA paper, timed for two hours, with the +3/−1 and Part B rules applied.
Every clear night: find two constellations and one planet, and note where they are.
If orbits and phases are hard to picture, the Fermi Simulation Lab has interactive simulations for ideas easier to see than read. For the physics side of the olympiads, see our guide to getting started with the physics olympiad.
Tonight, work out the orbital period of Jupiter (a = 5.2 AU) with T² = a³, then check your answer against a reference table.
