Knowledge Check: Solar System
1. Which term best describes the actual shape of the Earth?
- Perfect sphere
- Oval
- Oblate spheroid
- Cylindrical
Show Answer
Correct Answer: C) Oblate spheroid
Due to flattening at the poles and bulging at the equator, Earth is called an oblate spheroid.
2. Earth’s polar radius is _____ compared to the equatorial radius.
- Larger
- Equal
- Smaller
- Variable
Show Answer
Correct Answer: C) Smaller
Polar radius is slightly less than equatorial radius due to Earth’s rotation.
3. The widely accepted scientific explanation for the origin of the universe is the—
- Nebular theory
- Big Bang theory
- Steady State theory
- Expanding Matter theory
Show Answer
Correct Answer: B) Big Bang theory
The Big Bang theory states that the universe began from an extremely hot, dense state and has been expanding.
4. Approximate age of the universe is—
- 5 billion years
- 10 billion years
- 13.8 billion years
- 20 billion years
Show Answer
Correct Answer: C) 13.8 billion years
Current observations of cosmic background radiation and expansion support an age around 13.8 billion years.
5. Which unit is used to measure the distance between Earth and the Sun?
- Light year
- Parsecs
- Astronomical Unit (AU)
- Kelvin
Show Answer
Correct Answer: C) Astronomical Unit (AU)
1 AU is defined as the average distance between Earth and the Sun, about 150 million km.
6. Which galaxy contains our solar system?
- Andromeda Galaxy
- Milky Way Galaxy
- Pinwheel Galaxy
- Whirlpool Galaxy
Show Answer
Correct Answer: B) Milky Way Galaxy
The Sun and its planets are part of the Milky Way, a spiral galaxy.
7. The Sun is classified scientifically as a—
- Planet
- Satellite
- Medium-sized star
- Supernova
Show Answer
Correct Answer: C) Medium-sized star
The Sun is a main-sequence star of average size compared to other stars in the galaxy.
8. What type of orbit do planets follow around the Sun?
- Circular
- Rectangular
- Elliptical
- Spiral
Show Answer
Correct Answer: C) Elliptical
According to Kepler’s first law, planets move in elliptical orbits with the Sun at one focus.
9. Which planet takes the shortest time to orbit the Sun?
- Venus
- Mercury
- Earth
- Mars
Show Answer
Correct Answer: B) Mercury
Mercury, the closest planet to the Sun, completes one revolution in about 88 Earth days.
10. Earth completes one rotation on its axis in—
- 12 hours
- 24 hours
- 30 hours
- 48 hours
Show Answer
Correct Answer: B) 24 hours
One full spin of Earth on its axis defines one day of 24 hours.
11. Day and night occur due to—
- Revolution
- Rotation
- Tides
- Moon’s orbit
Show Answer
Correct Answer: B) Rotation
Rotation causes one hemisphere to face the Sun (day) while the opposite side has night.
12. One revolution of Earth around the Sun takes—
- 30 days
- 180 days
- 365¼ days
- 400 days
Show Answer
Correct Answer: C) 365¼ days
This extra quarter day is adjusted through leap year once in four years.
13. Seasons occur on Earth due to—
- Shape of Earth
- Revolution and axial tilt
- Atmospheric layers
- Moon’s phases
Show Answer
Correct Answer: B) Revolution and axial tilt
The changing angle of sunlight caused by tilt and revolution creates different seasons.
14. Earth’s axis is tilted at an angle of—
- 10°
- 15°
- 23.5°
- 45°
Show Answer
Correct Answer: C) 23.5°
The axis is tilted 23½° from the perpendicular to the orbital plane.
15. The imaginary line dividing Earth into Northern and Southern hemispheres is—
- Prime Meridian
- Tropic of Cancer
- Equator
- Arctic Circle
Show Answer
Correct Answer: C) Equator
The Equator is the 0° latitude line dividing Earth into two equal halves.
16. Lines running north-south on the globe are called—
- Latitudes
- Longitudes
- Parallels
- Bearings
Show Answer
Correct Answer: B) Longitudes
Longitudes, or meridians, join the North and South Poles and run north–south.
17. Which longitude is taken as the international reference for time?
- 23.5°
- 66.5°
- 90°
- 0° (Prime Meridian)
Show Answer
Correct Answer: D) 0° (Prime Meridian)
Greenwich Meridian (0°) is used as the reference for world standard time (GMT/UTC).
18. How much time difference does 1° of longitude represent?
- 1 minute
- 2 minutes
- 4 minutes
- 10 minutes
Show Answer
Correct Answer: C) 4 minutes
360° in 24 hours → 15° per hour → 1° per 4 minutes (24×60 / 360).
19. Which latitude is the northernmost point where the Sun can be directly overhead?
- Equator
- Tropic of Cancer (23.5° N)
- Tropic of Capricorn
- Arctic Circle
Show Answer
Correct Answer: B) Tropic of Cancer (23.5° N)
On about June 21, the Sun is overhead at the Tropic of Cancer, the northernmost overhead position.
20. The Arctic Circle lies at—
- 23.5° N
- 66.5° N
- 90° N
- 0°
Show Answer
Correct Answer: B) 66.5° N
Arctic Circle marks the southern limit of the North Polar region at about 66½° N latitude.
21. Which layer of the atmosphere contains the ozone layer?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
Show Answer
Correct Answer: B) Stratosphere
Ozone in the stratosphere absorbs harmful ultraviolet radiation from the Sun.
22. The hydrosphere includes—
- Only ocean water
- Groundwater, rivers, lakes, and oceans
- Only freshwater
- Polar ice only
Show Answer
Correct Answer: B) Groundwater, rivers, lakes, and oceans
Hydrosphere includes all forms of water present on or near Earth’s surface.
23. Lithosphere mainly includes—
- Gases
- Rocks and soil
- Water bodies
- Organisms
Show Answer
Correct Answer: B) Rocks and soil
Lithosphere is the solid outer layer of Earth consisting of crust and upper mantle materials.
24. Biosphere includes—
- Only land organisms
- Only aquatic organisms
- All living organisms
- Only plants
Show Answer
Correct Answer: C) All living organisms
Biosphere is the life-supporting zone including plants, animals, and micro-organisms on land and in water.
25. A constellation is—
- A group of planets
- A group of stars forming a pattern
- A single bright star
- A cluster of comets
Show Answer
Correct Answer: B) A group of stars forming a pattern
Constellations are star patterns identified and named by observers on Earth.
26. The constellation known for its three-star “belt” is—
- Ursa Major
- Orion
- Scorpius
- Lyra
Show Answer
Correct Answer: B) Orion
Orion, the Hunter, is easily recognised by three bright stars in a straight line (the “belt”).
27. Which constellation helps in locating the Pole Star?
- Leo
- Cassiopeia
- Ursa Major
- Orion
Show Answer
Correct Answer: C) Ursa Major
Extending a line from two stars of Ursa Major points approximately to the Pole Star in Ursa Minor.
28. The Pole Star appears almost fixed because it—
- Does not rotate
- Lies close to Earth
- Lies nearly above the Earth’s axis
- Is extremely small
Show Answer
Correct Answer: C) Lies nearly above the Earth’s axis
Since it is near the extension of Earth’s axis, its apparent position changes very little as Earth rotates.
29. A solar eclipse occurs when—
- Earth comes between Sun and Moon
- Moon comes between Sun and Earth
- Moon enters Earth’s shadow
- Sun enters Moon’s shadow
Show Answer
Correct Answer: B) Moon comes between Sun and Earth
The Moon blocks sunlight and casts its shadow on Earth, causing a solar eclipse for observers in that shadow region.
30. A lunar eclipse occurs during—
- New Moon
- Full Moon
- First Quarter
- Last Quarter
Show Answer
Correct Answer: B) Full Moon
Only during full moon can the Earth come directly between the Sun and the Moon and cast its shadow on the Moon.
31. Which eclipse can be seen by more people at the same time?
- Solar eclipse
- Lunar eclipse
- Annular eclipse
- None
Show Answer
Correct Answer: B) Lunar eclipse
Lunar eclipses are visible from the entire night side of Earth, making them observable by more people at once.
32. During a lunar eclipse, the positions are—
- Sun–Moon–Earth
- Earth–Sun–Moon
- Sun–Earth–Moon
- Moon–Earth–Sun
Show Answer
Correct Answer: C) Sun–Earth–Moon
Earth lies between Sun and Moon and casts its shadow on the Moon causing a lunar eclipse.
33. Which planet is known as the “Red Planet”?
- Venus
- Jupiter
- Mars
- Saturn
Show Answer
Correct Answer: C) Mars
Mars appears reddish due to iron oxide (rust-like) dust on its surface.
34. Which of the following does NOT have its own light?
- Stars
- Sun
- Planets
- Nebulae
Show Answer
Correct Answer: C) Planets
Planets shine by reflected light from their parent star; they are not self-luminous like stars.
35. The Earth is closest to the Sun in the position called—
- Aphelion
- Perihelion
- Equinox
- Solstice
Show Answer
Correct Answer: B) Perihelion
Perihelion is the point in Earth’s orbit where it is nearest to the Sun; aphelion is the farthest point.
36. Which body is the natural satellite of Earth?
- Mars
- Sun
- Moon
- Venus
Show Answer
Correct Answer: C) Moon
The Moon is Earth’s only natural satellite, orbiting it approximately every 27.3 days (sidereal month).
37. Earth’s revolution path around the Sun is best described as—
- Circular
- Zig-zag
- Elliptical
- Parabolic
Show Answer
Correct Answer: C) Elliptical
Earth’s orbit is elliptical, though very close to a circle, with Sun at one focus of the ellipse.
38. Light year is a unit of—
- Time
- Speed
- Distance
- Brightness
Show Answer
Correct Answer: C) Distance
A light year measures how far light travels in one year, used for large interstellar distances.
39. The correct hierarchical order (largest → smallest) is—
- Galaxy → Universe → Solar System
- Universe → Galaxy → Solar System
- Solar System → Galaxy → Universe
- Universe → Solar System → Galaxy
Show Answer
Correct Answer: B) Universe → Galaxy → Solar System
Universe contains galaxies, each galaxy can contain many star systems such as our solar system.
40. The Earth’s equatorial bulge is caused mainly by—
- Revolution
- Gravity
- Rotation
- Sun’s heat
Show Answer
Correct Answer: C) Rotation
Centrifugal force due to rotation produces bulging at the equator and flattening at the poles.
41. If the local time at Delhi (77° E) is 2:00 PM, what will be the local time at Chennai (80° E)?
Difference in longitude = 80°E – 77°E = 3°
Time difference = 3° × 4 minutes = 12 minutes (ahead)
- 1:48 PM
- 1:52 PM
- 2:12 PM
- 2:24 PM
Show Answer
Correct Answer: C) 2:12 PM
42. How much time difference is created by 1° of longitude?
- 1 minute
- 2 minutes
- 4 minutes
- 10 minutes
Show Answer
Correct Answer: C) 4 minutes
43. Earth completes 1° of rotation in approximately—
- 1 minute
- 2 minutes
- 4 minutes
- 6 minutes
Show Answer
Correct Answer: C) 4 minutes
44. The term “Paksha” in the context of Earth–Moon movement refers to—
- Half of the Earth’s orbit around the Sun
- Half of the Moon’s lunar cycle (around 15 days)
- The time Earth takes to rotate once
- The time difference between two full moons
Show Answer
Correct Answer: B) Half of the Moon’s lunar cycle (around 15 days)
45. A place located 15° west of another place will have its local time—
- 1 hour behind
- 1 hour ahead
- 4 minutes ahead
- 4 minutes behind
Show Answer
Correct Answer: A) 1 hour behind