Earth & Space
What makes Earth habitable?
It has water, air, and the atmosphere
What does the Big Bang theory suggest
The universe began as a hot, dense point and has been expanding.
What did Edwin Hubble discover?
The universe is expanding.
Why does the Sun produce so much energy?
Nuclear fusion in its core
What is a chemical reaction?
Atoms rearrange to form new substances.
What protects Earth from harmful radiation from space?
The atmosphere and magnetic field.
Who first proposed the Big Bang theory?
Georges Lemaître
What does redshift suggest?
Objects are moving away from us
What elements are fused in the Sun’s core?
Hydrogen atoms fuse into helium
What is a nuclear reaction?
Changes occur in the nucleus of an atom
What allows liquid water to exist on Earth?
Its distance from the Sun — the “Goldilocks Zone.”
What evidence supports the Big Bang?
Cosmic background radiation and redshift of galaxies.
What does blueshift suggest?
Objects are moving toward us
What form of energy does fusion release?
Light and heat energy.
How is a nuclear reaction different from a chemical reaction?
Nuclear reactions create new elements and release more energy.
What type of planet is Earth classified as?
A terrestrial (rocky) planet
What is cosmic microwave background radiation?
Leftover heat from the early universe
What is Hubble’s Law?
The farther a galaxy is, the faster it moves away.
What keeps the Sun from collapsing under its own gravity?
Outward pressure from fusion.
What type of reaction releases the most energy — nuclear or chemical?
Nuclear
Why is water essential for life on Earth?
It helps with chemical reactions and supports living cells.
About how old is the universe?
About 13.8 billion years old.
What do astronomers use to analyze light from stars?
Spectroscopy.
What type of reaction powers stars?
Nuclear fusion reactions.
What type of reaction powers nuclear bombs and the Sun?
Fusion reactions.