Solar System & the Sun MCQs with Answers

Solar System & the Sun — Master Reference for Pakistani Competitive Exams

The chapter Solar System & the Sun is a high-frequency Everyday Science / Astronomy topic in Pakistan’s PPSC, FPSC, NTS, CSS, PMS, OTS, CTS, BPSC, KPPSC and SPSC One Paper exams. Almost every Junior Clerk, Tehsildar, Assistant, Sub-Inspector, Lecturer and BPS-14 to BPS-17 paper carries 2–3 MCQs from this chapter — and it is core content for the CSS Screening MPT (General Science & Ability) paper. This page consolidates solved MCQs with answers covering the discovery of the Solar System (Nicolaus Copernicus), the Sun’s mass (1.989 × 10³⁰ kg), formation (~4.6 billion years ago from a solar nebula), composition (92.1% hydrogen + 7.8% helium), the seven layers (Core → Radiative Zone → Convection Zone → Photosphere → Chromosphere → Transition Region → Corona), distance from Earth (93 million miles / 150 million km = 1 AU; light takes 499 seconds), star type (G2V Yellow Dwarf), proton-proton fusion, Kepler’s First Law (1609), comets, asteroids, the equinox (vernal/autumnal) and the galactic year. For wider context, see Wikipedia: Solar System and NASA Science: The Sun — the official NASA reference.

The Sun — Key Numbers

Layers of the Sun

Key Facts to Memorise

• Solar System discovered by — Nicolaus Copernicus (heliocentric model).
• Sun’s mass — 1.989 × 10³⁰ kg (per NASA); about 99.8% of the solar system’s total mass.
• Sun and solar system formed — ~4.6 billion years ago from a giant rotating cloud of gas & dust called a solar nebula.
• Sun’s composition — 92.1% hydrogen + 7.8% helium.
• 109 Earths would fit across the Sun’s diameter; 1.3 million Earths could fit inside its volume.
• Photosphere — the Sun’s outer visible layer; ~5,500 °C (10,000 °F).
• Sun’s core temperature — ~15 million °C.
• Distance Earth-Sun — 93 million miles (150 million km) = 1 Astronomical Unit (AU).
• Light travel time Sun → Earth — about 499 seconds (~8 min 19 sec).
• Sun’s star type — main-sequence G2V star or Yellow Dwarf.
• The Sun does NOT have rings.
• Sun emits shortwave radiation — because it is extremely hot.
• Fusion in the Sun — known as proton-proton fusion.
• Kepler’s First Law (1609) — Planets move in ellipses with the Sun at one focus.
• Comets — cosmic snowballs of frozen gases, rock and dust that orbit the Sun.
• Asteroids — small, rocky objects that orbit the Sun.
• Equinox — when the Sun is vertically above the Equator. Occurs twice a year (March = Vernal/Spring; September = Autumnal/Fall).
• Japan — known as the “Land of the Rising Sun” for at least 1,400 years.
• Galactic year (cosmic year) — the time required for the Sun to orbit once around the centre of the Milky Way Galaxy.