OBA Practice Questions - 29a Olimpíada Brasileira De Astronomia E Astronáutica - 2026 Exam

What is the primary astronomical cause of the annual cycle of seasons on Earth?

The constant 23.44° tilt of Earth's rotational axis relative to the ecliptic plane as it revolves around the Sun The periodic variation in distance between the Earth and the Sun due to Earth's orbital eccentricity (perihelion vs aphelion) The periodic fluctuation in the Sun's total solar irradiance and magnetic activity over an 11-year cycle The gravitational precession of Earth's rotational axis relative to the background constellations

Correct Answer:

The constant 23.44° tilt of Earth's rotational axis relative to the ecliptic plane as it revolves around the Sun

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