Asteroid Destruction Hypothesis Explains Mars’ Unusual Moons

Why in the news?

A recent study suggests Mars’ moons, Phobos and Deimos, originated from a large asteroid torn apart by Mars’ gravity, solving the mystery of their unique orbits.

Asteroid Destruction Hypothesis Explains Mars' Unusual Moons

Introduction: Mars’ Peculiar Moons:

  • Mars has two small, lumpy moons: Phobos (27 km) and Deimos (15 km).
  • Their irregular shapes and asteroid-like features have led scientists to hypothesize they originated as asteroids.
  • However, their circular and equatorial orbits conflict with the typical asteroid capture theory.

New Hypothesis: Asteroid Destruction:

  • A new study proposes that a large asteroid was captured by Mars’ gravity millions of years ago.
  • The asteroid approached Mars closely (as near as 5,150 km) and was torn apart by the planet’s gravity.
  • Some fragments escaped, while others hit Mars, leaving craters. Remaining pieces collided, forming a debris cloud around Mars’ equator.
  • Over time, gravitational influences from Mars and the Sun caused the debris to clump together, creating Phobos and Deimos.
  • Supercomputer simulations support this hypothesis, explaining the moons’ unique orbits and structure.

Challenges to the Asteroid Capture Theory:

  • Captured asteroids typically have tilted and elliptical orbits, unlike the neat orbits of Phobos and Deimos.
  • Circular orbits suggest the moons were not merely captured but formed differently, possibly similar to Earth’s moon’s origin.
  • Scientists theorize that debris from a collision or other significant event could have formed these moons, aligning their orbits with Mars’ equator.

Characteristics of Newly Discovered Moons:

  • Uranus’ Moon (S/2023 U1):
    • Diameter: ~5 miles (8 km).
    • Among the smallest known moons in the solar system.
  • Neptune’s Moons:
    • S/2002 N5: Diameter ~14.3 miles (23 km).
    • S/2021 N1: Diameter ~8.7 miles (14 km).
  • Discovered using ground-based telescopes despite vast distances and small sizes.

About the Moons in the Solar System:

  • Moons orbit planets, dwarf planets, and large asteroids, offering insights into celestial dynamics.
  • Types of Moons:
  • Regular Moons: Prograde orbits near equatorial planes.
  • Irregular Moons: Inclined orbits, often captured.
  • Moon Highlights by Body:
  • Earth: 1 Moon (largest relative to planet).
  • Mars: 2 Moons (Phobos, Deimos).
  • Jupiter: 95 Moons (e.g., Galilean moons).
  • Saturn: 146 Moons (Titan).
  • Uranus: 28 Moons (Shakespearean names).
  • Neptune: 16 Moons (Triton).
  • Pluto: 5 Moons (Charon).

Sources Referred:

PIB, The Hindu, Indian Express, Hindustan Times