Astrophysics and the Universe Quiz

Grade 12 · Science · Quiz

Test your knowledge of stars, galaxies, cosmology, and the structure of the universe.

Questions

What is the primary evidence that the universe is still expanding?
1. The existence of black holes
2. The redshift of distant galaxies
3. The presence of dark matter
4. The age of the oldest stars
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Answer: The redshift of distant galaxies
When galaxies move away from us, their light is stretched to longer (redder) wavelengths — called redshift. The farther the galaxy, the greater the redshift, indicating the universe is expanding uniformly.
A neutron star is less dense than a white dwarf.
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Answer: False
Neutron stars are far denser than white dwarfs. A neutron star teaspoon would weigh ~1 billion tons; white dwarfs are dense but only comparable to Earth's core density.
Stars form from collapsing clouds of gas and dust called ___.
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Answer: nebulae
Nebulae are vast clouds of gas (mostly hydrogen) and dust. Gravity causes regions within to collapse, forming protostars that heat up until nuclear fusion ignites.
What force triggers nuclear fusion in the core of a protostar?
1. Electromagnetic force
2. Strong nuclear force
3. Gravitational compression raising temperature and pressure
4. Weak nuclear force
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Answer: Gravitational compression raising temperature and pressure
As a nebula contracts under gravity, the core temperature and pressure rise enormously. When the core reaches ~10 million Kelvin, hydrogen fusion begins, and the star 'turns on.'
The Milky Way is classified as an elliptical galaxy.
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Answer: False
The Milky Way is a barred spiral galaxy with a central bar-shaped bulge and spiral arms. Elliptical galaxies are rounder, contain older stars, and have little gas for new star formation.
Which element is most abundant in the universe?
1. Helium
2. Oxygen
3. Carbon
4. Hydrogen
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Answer: Hydrogen
Hydrogen (~75%) and helium (~24%) make up about 99% of all ordinary matter in the universe. All heavier elements were formed in stars or the Big Bang.
The point of no return around a black hole, beyond which light cannot escape, is called the event ___.
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Answer: horizon
The event horizon is the boundary around a black hole where escape velocity equals the speed of light. Anything crossing inward — matter or photons — cannot escape.
Heavy elements like iron and gold were primarily formed in the Big Bang.
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Answer: False
The Big Bang primarily produced only hydrogen, helium, and trace lithium. Elements heavier than helium (carbon, oxygen, iron, gold, etc.) were forged in stellar nucleosynthesis and dispersed by supernovae.
According to current estimates, dark energy makes up approximately what percentage of the universe's mass-energy?
1. 5%
2. 27%
3. 68%
4. 95%
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Answer: 68%
Current measurements: ~68% dark energy, ~27% dark matter, ~5% ordinary (baryonic) matter. Dark energy is responsible for the accelerating expansion of the universe discovered in 1998.
The cosmic microwave background radiation was first detected in:
1. 1905
2. 1929
3. 1965
4. 1990
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Answer: 1965
Arno Penzias and Robert Wilson discovered the CMB in 1965 at Bell Labs while troubleshooting microwave antenna noise. It was the strongest confirmation of the Big Bang theory and earned them the 1978 Nobel Prize.

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