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Observing Space / Astronomy — Homi Bhabha Exam Physics MCQs with Solutions
Free Homi Bhabha Exam Physics Observing Space / Astronomy MCQs with step-by-step solutions covering Constellations, Solar System Dynamics, Satellites (Natural & Artificial), Life Cycle of Stars, Telescopes. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — Constellations · hard · theory
The Pole Star (Dhruva Tara) appears almost stationary in the sky because it lies:
A. nearly above the axis of rotation of the Earth ✓ Correct
B. on the equator
C. at the centre of the solar system
D. very close to the Earth
Solution: The Pole Star is nearly in line with the Earth's rotational axis, so it barely appears to move.
Q2 — Constellations · hard · theory
The two "pointer stars" of Ursa Major are useful because they:
A. point towards the Pole Star ✓ Correct
B. point towards the Sun
C. point towards the Moon
D. always point east
Solution: A line through the two end stars of the Big Dipper points to the Pole Star, aiding navigation.
Q3 — Constellations · hard · theory
The stars that make up a constellation are:
A. all at the same distance from Earth
B. all part of the solar system
C. physically bound close together
D. usually at very different distances and not physically close to one another ✓ Correct
Solution: Stars in a constellation merely appear together from Earth; they are actually at widely different distances.
Q4 — Solar System Dynamics · hard · theory
The asteroid belt of the solar system lies mainly between the orbits of:
A. Earth and Mars
B. Jupiter and Saturn
C. Mars and Jupiter ✓ Correct
D. Venus and Earth
Solution: The main asteroid belt is located between Mars and Jupiter.
Q5 — Solar System Dynamics · hard · theory
A planet closer to the Sun completes one revolution in a shorter time than a distant planet. Therefore, the planet with the shortest year is:
A. Saturn
B. Jupiter
C. Mercury ✓ Correct
D. Neptune
Solution: Being closest, Mercury moves fastest and has the shortest orbital period (year).
Q6 — Satellites (Natural & Artificial) · hard · theory
A geostationary satellite appears to stay fixed above one point on the Earth because its orbital period is:
A. exactly 12 hours
B. about 24 hours (equal to the Earth's rotation period) ✓ Correct
C. about 1 month
D. about 1 hour
Solution: A geostationary satellite orbits once every ~24 hours over the equator, matching the Earth's spin, so it appears stationary.
Q7 — Satellites (Natural & Artificial) · hard · theory
A satellite remains in its orbit around the Earth because:
A. the Sun pushes it
B. the gravitational pull of the Earth provides the required centripetal force ✓ Correct
C. its engines fire continuously
D. there is no gravity in space
Solution: Earth's gravity supplies the centripetal force that keeps the satellite moving in its circular/elliptical orbit.
Q8 — Life Cycle of Stars · hard · theory
Stars, including the Sun, produce their enormous energy by:
A. chemical reactions
B. burning coal
C. nuclear fusion of hydrogen into helium ✓ Correct
D. nuclear fission of uranium
Solution: In the core, hydrogen nuclei fuse into helium, releasing vast energy (nuclear fusion).
Q9 — Life Cycle of Stars · hard · theory
A medium-sized star like the Sun will, near the end of its life, first swell into a:
A. white dwarf directly
B. neutron star
C. black hole
D. red giant ✓ Correct
Solution: A Sun-like star expands into a red giant, then sheds its outer layers to leave a white dwarf.
Q10 — Life Cycle of Stars · hard · theory
A very massive star ends its life in a huge explosion called a:
A. meteor shower
B. nebula
C. solar eclipse
D. supernova ✓ Correct
Solution: Massive stars explode as supernovae, leaving behind a neutron star or a black hole.
Q11 — Telescopes · hard · theory
A refracting telescope forms images using ______, while a reflecting telescope uses ______:
A. prisms; lenses
B. mirrors; lenses
C. mirrors; prisms
D. lenses; mirrors ✓ Correct
Solution: Refractors use lenses to bend light; reflectors use curved mirrors to gather and focus it.
Q12 — Telescopes · hard · theory
A telescope with a larger objective (aperture) is better because it:
A. magnifies without any lens
B. collects more light and can show fainter objects ✓ Correct
C. is cheaper to build
D. needs no focusing
Solution: A bigger aperture gathers more light, allowing fainter and more distant objects to be seen.
Q13 — Constellations · medium · theory
A constellation is:
A. a group of galaxies
B. a single very bright star
C. a cluster of planets
D. a group of stars that appears to form a recognisable pattern in the sky ✓ Correct
Solution: A constellation is a recognisable pattern formed by stars as seen from Earth.
Q14 — Constellations · medium · theory
The constellation Ursa Major is also known in India as:
A. Orion
B. Sirius
C. Saptarshi ✓ Correct
D. Mrig
Solution: Ursa Major (the Great Bear / Big Dipper) is called Saptarshi in India.
Q15 — Constellations · medium · theory
Constellations appear to move slowly across the night sky mainly because of:
A. the expansion of space
B. the Moon's gravity
C. the Earth's rotation ✓ Correct
D. the stars orbiting the Earth
Solution: The apparent motion of constellations is due to the Earth spinning on its axis.
Q16 — Solar System Dynamics · medium · theory
The planets revolve around the Sun in orbits that are:
A. square
B. elliptical ✓ Correct
C. perfectly circular
D. straight lines
Solution: As described by Kepler, planetary orbits are ellipses with the Sun at one focus.
Q17 — Solar System Dynamics · medium · theory
The planet nearest to the Sun is:
A. Earth
B. Mars
C. Mercury ✓ Correct
D. Venus
Solution: Mercury is the innermost planet of the solar system.
Q18 — Solar System Dynamics · medium · theory
The largest planet in the solar system is:
A. Earth
B. Jupiter ✓ Correct
C. Neptune
D. Saturn
Solution: Jupiter is the biggest planet by both diameter and mass.
Q19 — Solar System Dynamics · medium · theory
The terrestrial (rocky) inner planets of the solar system are:
A. Mercury, Venus, Earth and Mars ✓ Correct
B. Venus, Jupiter, Earth and Neptune
C. Earth, Jupiter, Saturn and Mars
D. Jupiter, Saturn, Uranus and Neptune
Solution: The four inner planets — Mercury, Venus, Earth, Mars — are small and rocky (terrestrial).
Q20 — Satellites (Natural & Artificial) · medium · theory
A natural satellite of the Earth is the:
A. Moon ✓ Correct
B. International Space Station
C. Sun
D. INSAT
Solution: The Moon is Earth's only natural satellite; the others listed are man-made or stars.
Q21 — Satellites (Natural & Artificial) · medium · theory
Artificial satellites are commonly used for:
A. communication, weather forecasting and navigation ✓ Correct
B. purifying drinking water
C. growing crops in space
D. producing electricity for homes
Solution: Man-made satellites serve communication, weather monitoring, remote sensing and GPS navigation.
Q22 — Satellites (Natural & Artificial) · medium · theory
India's first artificial satellite, launched in 1975, was named:
A. Mangalyaan
B. INSAT-1A
C. Chandrayaan
D. Aryabhata ✓ Correct
Solution: Aryabhata was India's first satellite, launched in 1975.
Q23 — Satellites (Natural & Artificial) · medium · theory
Which of the following is an Indian series of satellites used for telecommunication and broadcasting?
A. Voyager
B. INSAT ✓ Correct
C. GPS
D. Hubble
Solution: The INSAT (Indian National Satellite) series handles communication and weather services.
Q24 — Life Cycle of Stars · medium · theory
Stars are born from huge clouds of gas and dust called:
A. craters
B. comets
C. asteroids
D. nebulae ✓ Correct
Solution: A star forms when a nebula (cloud of gas and dust) contracts under gravity.
Q25 — Life Cycle of Stars · medium · theory
The main fuel that powers the Sun at present is:
A. oxygen
B. carbon
C. helium
D. hydrogen ✓ Correct
Solution: The Sun mainly fuses hydrogen into helium in its core.
Q26 — Life Cycle of Stars · medium · theory
The final remnant of a low-mass star like the Sun, after it has exhausted its fuel, is a:
A. red giant
B. black hole
C. supernova
D. white dwarf ✓ Correct
Solution: After the red giant stage, a Sun-like star leaves a small, dense, hot white dwarf.
Q27 — Telescopes · medium · theory
A telescope is used to:
A. record sound from space
B. observe distant celestial objects by collecting more light ✓ Correct
C. magnify very small nearby objects
D. measure temperature of stars directly
Solution: A telescope gathers light from far-off objects, making them appear brighter and larger.
Q28 — Telescopes · medium · theory
The famous space telescope that orbits the Earth above the atmosphere is the:
A. Galileo telescope
B. Radio telescope at Pune
C. Hubble Space Telescope ✓ Correct
D. INSAT
Solution: The Hubble Space Telescope orbits Earth, giving clear images free of atmospheric distortion.
Q29 — Telescopes · medium · theory
A radio telescope is used to detect ______ coming from space:
A. visible light only
B. X-rays only
C. sound waves
D. radio waves ✓ Correct
Solution: Radio telescopes collect radio-wave signals emitted by celestial objects.
Q30 — Telescopes · medium · theory
The scientist who first used a telescope to study the sky (observing Jupiter's moons and craters on the Moon) was:
A. Isaac Newton
B. Galileo Galilei ✓ Correct
C. C. V. Raman
D. Albert Einstein
Solution: Galileo pioneered telescopic astronomy in the early 17th century.