The Cosmic Microwave Background Radiation (CMBR) refers to:
- AThe cosmic rays emitted by the Sun and other astrophysical objects
- BThe residual thermal radiation from the Big Bang that fills the entire universe
- CThe electromagnetic radiation emitted by stars in the microwave frequency range
- DThe radiation emitted by the heaviest stars in the galaxy
Show answer and explanation
Correct answer: (b) The residual thermal radiation from the Big Bang that fills the entire universe
Explanation
The cosmic microwave background radiation (CMBR) is the faint glow of microwave radiation that fills the whole universe almost evenly. It is the leftover heat of the Big Bang.
About 380,000 years after the Big Bang, the universe cooled enough for atoms to form and light to travel freely. As the universe expanded, that light was stretched into microwaves. Its temperature today is about 2.7 K. It was found by chance in the mid-1960s by Arno Penzias and Robert Wilson, and it is strong evidence for the Big Bang theory.