Astronomy Cosmology and Deep Space

Question 1

What is the Big Bang theory?

Accepted Answer

The prevailing cosmological model explaining the universe's origin from an extremely hot, dense state approximately 13.8 billion years ago

Answer

The Big Bang theory describes the universe expanding from an extremely hot, dense singularity approximately 13.8 billion years ago, supported by evidence including cosmic microwave background radiation, Hubble's Law, and primordial element abundances.

Question 2

What is dark matter?

Accepted Answer

An unknown form of matter that doesn't emit or absorb light but exerts gravitational effects, comprising about 27% of the universe

Answer

Dark matter is a hypothetical form of matter that doesn't interact with electromagnetic radiation but reveals its presence through gravitational effects on visible matter, galaxy rotation curves, and gravitational lensing.

Question 3

What is the cosmic microwave background radiation?

Accepted Answer

Faint radiation from approximately 380,000 years after the Big Bang, filling all of space uniformly

Answer

The CMB is thermal radiation released when the universe cooled enough for atoms to form (recombination era, ~380,000 years after the Big Bang), now observed as microwave radiation at about 2.7 Kelvin.

Question 4

What is Hubble's Law and what does it tell us about the universe?

Accepted Answer

The recessional velocity of galaxies is proportional to their distance — evidence that the universe is expanding

Answer

Hubble's Law (v = H₀d) states that the farther a galaxy is from us, the faster it's moving away, demonstrating that the universe is expanding and providing evidence supporting the Big Bang theory.

Question 5

What is a galaxy and what types exist?

Accepted Answer

A gravitationally bound system of stars, gas, dust, and dark matter; types include spiral, elliptical, and irregular

Answer

Galaxies are massive systems containing billions of stars, gas, dust, and dark matter held together by gravity. Major types are spiral (like the Milky Way), elliptical (round/oval), and irregular (no defined shape).

Astronomy Practice Test

Astronomy Practice Test

Astronomy Cosmology and Deep Space