Question

Consider the following astronomical statements. Classify each statement as either an observation, meaning something we have directly observed or measured, or an explanation, meaning something that we infer from observational or experimental evidence even though we cannot observe it directly.

[Observations]
- The Andromeda Galaxy is similar in structure to our own Milky Way
- All planets orbit the Sun in the same direction and nearly the same plane
- More distant galaxies are moving away from us faster than nearby galaxies
- Stars can shine brightly for billions of years

Answer 1

[Observations]

- The Andromeda Galaxy is similar in structure to our own Milky Way

- All planets orbit the Sun in the same direction and nearly the same plane

- More distant galaxies are moving away from us faster than nearby galaxies

- Stars can shine brightly for billions of years

[Explanations]

- The universe is expanding because it began with a Big Bang

- The Andromeda and Milky Way galaxies formed in the same way

- The orderly orbits of planets arose from their formation in a rotating gas cloud

- Stars shine with energy generated by nuclear fusion in their cores