Relevance: GS-3 (Space Technology)
Source: NASA, New Atlas, The Hindu

NASA’s Voyager 1 spacecraft is now approaching 1 light-day (≈26 billion kilometres) from Earth—making it the most distant human-made object. The milestone highlights the durability of deep-space probes and advances in interstellar exploration.

About the Voyager Spacecraft

• Launched in 1977 by NASA  for outer-planet exploration.
• Voyager 1 entered interstellar space in 2012; Voyager 2 in 2018.
• Carry the Golden Record containing sounds and images of Earth.

What Is a Light-Day? 

A light-day is the distance light travels in 24 hours.

• 1 light-day ≈ 26 billion km.
  

 Other key astronomical distance units:

• Astronomical Unit: Distance Earth–Sun (≈150 million km).
• Light-year: Distance light travels in 1 year.
• Parsec: ≈ 3.26 light-years (used for stellar distances).

Significance for Human Civilization

The milestone helps understand astronomical scales, deep-space communication, interstellar medium, and India’s growing interest in space science (e.g., Aditya-L1, future interplanetary missions).

Q. Which of the following correctly matches the astronomical unit with what it measures?

1. Light-day — Distance between Earth and Moon
2. Astronomical Unit — Average Earth–Sun distance
3. Parsec — Distance light travels in one day

Select the correct answer:
A. 2 only;  B. 1 and 3 only; 

C. 1 and 2 only;  D. 2 and 3 only