In News:

Scientists have confirmed the discovery of 3I/Atlas, the third-known interstellar object, which could be over 7 billion years old — predating the Solar System by nearly 3 billion years. It was detected on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile.

Key Features:

• Interstellar Origin: 3I/Atlas is not gravitationally bound to the Sun and follows a hyperbolic trajectory, indicating it entered the Solar System from interstellar space.
• High Speed: It is traveling at approximately 60 km/s — too fast to be retained by the Sun’s gravity at a distance of 670 million km from the Sun.
• Current Location: The object is now roughly 917 million km from Earth, close to the orbit of Jupiter.
• Age Estimation: Estimated to be around 7 billion years old, making it potentially the oldest comet ever observed.

Understanding Interstellar Objects

• Definition: Interstellar objects are celestial bodies that originate outside the Solar System and pass through it without being gravitationally bound to the Sun.
• Known Interstellar Objects:
  • 1I/?Oumuamua (2017)
  • 2I/Borisov (2019)
  • 3I/Atlas (2025)

How do scientists confirm Interstellar Origin?

• Trajectory Analysis: Objects within the Solar System follow closed elliptical orbits. Interstellar objects exhibit open hyperbolic orbits — they have a perihelion (closest point to the Sun) but no aphelion (no return).
• Velocity Measurement: A high velocity at a great distance from the Sun, such as with 3I/Atlas, suggests that the object was not accelerated within our Solar System and must have originated externally.
  • Example: At 670 million km from the Sun, 3I/Atlas’s speed of 60 km/s indicates a hyperbolic escape path, unaffected significantly by the Sun’s gravitational pull.

Why is it Significant?

• Clues to Alien Planetary Systems: The chemical composition of interstellar objects offers insights into the formation conditions of other star systems.
• Rare Opportunity: These objects provide a direct sample of exoplanetary material, potentially long before space missions can reach other star systems.
• Scientific Value: If rich in ices, as expected in long-distance comets, it implies ejection from a cold, outer region of a distant planetary system—likely influenced by large planets like Jupiter or Neptune analogues.