List of gravitationally rounded objects of the Solar System - Quiz
List of gravitationally rounded objects of the Solar System
  • 1. How many natural satellites in the Solar System are known to be massive enough to be close to hydrostatic equilibrium?
A) 19
B) 17
C) 22
D) 15
  • 2. How many of the gravitationally rounded natural satellites belong to Saturn?
A) Five
B) Four
C) One
D) Seven
  • 3. What is the term used by Alan Stern for gravitationally rounded natural satellites?
A) Planetary satellites
B) Satellite planets
C) Major moons
D) Dwarf moons
  • 4. Which is the smallest natural satellite known to be gravitationally rounded?
A) Hyperion
B) Mimas
C) Proteus
D) Phoebe
  • 5. Which natural satellite is known not to be gravitationally rounded despite being larger than Mimas?
A) Rhea
B) Proteus
C) Titan
D) Io
  • 6. What is the radius of the smallest rounded satellite, Mimas?
A) 198.2 km
B) 135 km
C) 106.5 km
D) 210 km
  • 7. Which of these moons is considered to still be in equilibrium today?
A) Phoebe
B) Hyperion
C) Mimas
D) Io
  • 8. Why are the moons of trans-Neptunian objects (other than Charon) generally not included in the list?
A) They become solid at a larger size than the moons of Saturn and Uranus
B) They have not been discovered yet
C) They are all irregular in shape
D) They are too small to be seen
  • 9. What is the approximate diameter at which TNO moons become solid?
A) 200–300 km
B) 400–500 km
C) 900–1000 km
D) 1200–1500 km
  • 10. Which satellite is the fifth largest round satellite of Uranus, despite being the innermost?
A) Miranda
B) Mimas
C) Triton
D) Titan
  • 11. What is the reason the Roman numeral system for moons does not always reflect distance from the parent planet?
A) The planets move around the Sun
B) Scientists update the names every century
C) The moons change their orbits over time
D) It follows the order of discovery since 1892
  • 12. Which moon is Saturn VII and is not large enough to be round?
A) Mimas
B) Hyperion
C) Phoebe
D) Rhea
  • 13. Which of these satellites is mentioned as having a known low density in addition to being a dark body?
A) Callisto
B) Dysnomia
C) Ganymede
D) Europa
  • 14. How many round satellites belong to Jupiter?
A) Seven
B) Four
C) One
D) Five
  • 15. What is the radius of the non-rounded moon Phoebe?
A) 198.2 km
B) 210 km
C) 106.5 km
D) 135 km
  • 16. What percentage of the Solar System's mass does the Sun contain?
A) Approximately 95%
B) Almost 99.9%
C) About 99.5%
D) Roughly 90%
  • 17. What is the official classification of the Sun?
A) Gas giant
B) Red giant
C) White dwarf
D) G-type main-sequence star
  • 18. How many planets are officially recognized by the IAU?
A) Eight
B) Nine
C) Seven
D) Ten
  • 19. Which planet is round but not actually in hydrostatic equilibrium?
A) Mercury
B) Venus
C) Earth
D) Mars
  • 20. Where does Ceres orbit?
A) Between Venus and Earth
B) Beyond Neptune
C) Near the Galactic Center
D) In the asteroid belt
  • 21. What suggests that many TNOs in the 200–500 km range are not planetary bodies?
A) Rapid rotation
B) Internal porosity
C) Lack of methane
D) High surface temperature
  • 22. What molecule, detected by the James Webb Space Telescope, implies methane is resupplied from internal geochemistry?
A) Carbon monoxide
B) Ethane
C) Nitrogen
D) Helium
  • 23. Which moon is described as too oblate for its current spin, similar to Quaoar?
A) Titan
B) Iapetus
C) Europa
D) Triton
  • 24. Which asteroid is the second-largest and likely had a differentiated interior?
A) Hygiea
B) Pallas
C) Vesta
D) Interamnia
  • 25. Which asteroid is the third-largest and appears never to have completed differentiation?
A) Vesta
B) Interamnia
C) Hygiea
D) Pallas
  • 26. According to the IAU, what must a planet do besides reaching hydrostatic equilibrium?
A) Clear the neighbourhood around its orbit
B) Possess at least one moon
C) Maintain a magnetic field
D) Orbit a star smaller than the Sun
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