Correct Answer - Option 4 : i, ii, iii & iv only
The correct answer is i, ii, iii & iv only.
- The size of the whole universe is unknown, and it might be infinite in extent.
- According to the Big Bang theory, the very early Universe was an extremely hot and dense state about 13.8 billion years ago which rapidly expanded.
- About 380,000 years later the Universe had cooled sufficiently to allow protons and electrons to combine and form hydrogen—the so-called recombination epoch.
- When this happened, matter and energy became decoupled, allowing photons to travel freely through the continually expanding space.
- The matter that remained following the initial expansion has since undergone gravitational collapse to create stars, galaxies, and other astronomical objects, leaving behind a deep vacuum that forms what is now called outer space.
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Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays.
- The final boundary between the Earth and the outer space (magnetosphere) is called the magnetopause.
- The magnetopause is a region of the Earth’s Magnetosphere.
- The boundary between the Earth and outer space dominated by the planet's magnetic field.