Barcodes of the Sky: Light Spectra Big Bang Evidence

  • 11th Grade
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| Questions: 20 | Updated: Feb 13, 2026
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1. What phenomenon occurs when a galaxy moves away from Earth, causing its spectral lines to shift toward longer wavelengths?

Explanation

If a light source moves away from an observer, then the waves are stretched; if the waves are stretched, their wavelength increases; if the wavelength increases, the light shifts toward the red end of the spectrum.

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About This Quiz
Barcodes Of The Sky: Light Spectra Big Bang Evidence - Quiz

A cosmic barcode that reveals the past. By splitting starlight into its component colors, scientists can see exactly how the universe has shifted since its first moments. This light spectra big bang evidence quiz deciphers the colorful patterns that prove where we came from.

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2. The Big Bang Theory predicts that the universe is currently static and unchanging in size.

Explanation

If the Big Bang occurred, then space itself has been expanding since that initial event; if space is expanding, then the universe cannot be static.

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3. Which scientist's observations in the 1920s provided the first spectral evidence that distant galaxies are moving away from us?

Explanation

If a scientist measured the distances and redshifts of galaxies, and if he found a linear relationship between them, then that scientist was Edwin Hubble.

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4. The ________ ________ Background radiation is the "afterglow" of the Big Bang, discovered as a faint microwave signal coming from all directions.

Explanation

If the universe was once extremely hot and dense, then it must have cooled as it expanded; if it cooled, the original high-energy radiation would be stretched into the microwave range, which is the Cosmic Microwave Background.

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5. When looking at the absorption spectrum of a distant galaxy, how do the dark lines appear compared to a laboratory sample on Earth?

Explanation

If the galaxy is receding from Earth, then its light undergoes cosmological redshift; if redshift occurs, then the specific dark absorption lines will appear at longer (redder) wavelengths than they do on Earth.

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6. Which of the following are considered primary pieces of evidence for the Big Bang Theory?

Explanation

If the Big Bang model is correct, then it must explain the expansion (redshift), the leftover heat (CMB), and the chemical makeup of the early universe (nucleosynthesis); items A, B, and C satisfy these requirements.

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7. A "Blueshift" indicates that a galaxy is moving toward the observer.

Explanation

If a light source moves toward an observer, then the waves are compressed; if waves are compressed, the wavelength decreases; if the wavelength decreases, the light shifts toward the blue/violet end of the spectrum.

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8. What does Hubble's Law state about the relationship between a galaxy's distance and its velocity?

Explanation

If the expansion of space is uniform, then a galaxy twice as far away has twice as much expanding space between us and it; if there is more expanding space, then the recession velocity must be proportionally higher.

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9. The shift in wavelength caused by the relative motion between a source and an observer is known as the ________ Effect.

Explanation

If a source of waves moves relative to an observer, then the observed frequency changes; if this specific physical principle is applied to sound or light, it is defined as the Doppler Effect.

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10. Why is the Cosmic Microwave Background (CMB) detected in the microwave part of the spectrum today?

Explanation

If the early universe emitted high-energy visible or UV light, and if space has expanded by a factor of about 1,000 since then, then the wavelengths must have stretched by that same factor into the microwave range.

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11. Spectral lines are caused by electrons jumping between specific energy levels within atoms.

Explanation

If atoms absorb or emit specific amounts of energy, then electrons transition between discrete levels; if these transitions occur, they create distinct lines at specific wavelengths in a spectrum.

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12. Most of the matter in the early universe, as predicted by the Big Bang and confirmed by spectra, consisted of which two elements?

Explanation

If the early universe was hot enough for fusion for only a few minutes, then only the simplest nuclei could form; if simplicity is the constraint, then Hydrogen (~75%) and Helium (~25%) are the resulting products.

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13. A spectrum that shows all colors of the rainbow without any gaps is called a ________ spectrum.

Explanation

If a dense, hot object emits light at all possible wavelengths in a range, then there are no missing frequencies; if there are no missing frequencies, the spectrum is described as continuous.

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14. If the universe were contracting instead of expanding, what would we observe in the spectra of distant galaxies?

Explanation

If the universe were shrinking, then galaxies would be moving toward us; if they move toward us, the light waves would compress (shorter wavelength) and show a blueshift.

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15. The "Cosmological Redshift" is caused by galaxies moving through space like bullets, rather than space itself expanding.

Explanation

If the Big Bang involves the expansion of the "fabric" of space, then the light is stretched as it travels through that expanding fabric; therefore, it is space expanding, not just galaxies moving through static space.

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16. How does the temperature of the Cosmic Microwave Background (CMB) provide evidence for the Big Bang?

Explanation

If the universe started in a hot state and expanded, then it must have cooled to a very low, predictable temperature; if we measure that temperature to be 2.7K everywhere, then it confirms the cooling prediction.

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17. An ________ spectrum consists of dark lines superimposed on a continuous spectrum.

Explanation

If light from a hot source passes through a cooler gas, then the gas atoms will soak up specific wavelengths; if those wavelengths are removed, the resulting display is an absorption spectrum.

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18. If a galaxy's spectral lines are shifted significantly more than another galaxy's, what can we conclude?

Explanation

If Hubble's Law (v = H0 * d) is correct, then velocity is proportional to distance; if a larger shift means a higher velocity, then a larger shift must also mean a greater distance.

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19. The discovery of the CMB was accidental, found by researchers using a horn antenna for satellite communication.

Explanation

If Penzias and Wilson were trying to remove "noise" from their radio antenna and found a persistent signal from all directions, and if that signal matched Big Bang predictions, then the discovery was indeed accidental.

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20. Which type of spectrum is produced by a hot, low-density gas?

Explanation

If a gas is thin and hot, its atoms are far apart and emit light only at specific energy transitions; if it emits light only at specific wavelengths, it produces bright lines known as an emission spectrum.

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What phenomenon occurs when a galaxy moves away from Earth, causing...
The Big Bang Theory predicts that the universe is currently static and...
Which scientist's observations in the 1920s provided the first...
The ________ ________ Background radiation is the "afterglow" of the...
When looking at the absorption spectrum of a distant galaxy, how do...
Which of the following are considered primary pieces of evidence for...
A "Blueshift" indicates that a galaxy is moving toward the observer.
What does Hubble's Law state about the relationship between a galaxy's...
The shift in wavelength caused by the relative motion between a source...
Why is the Cosmic Microwave Background (CMB) detected in the microwave...
Spectral lines are caused by electrons jumping between specific energy...
Most of the matter in the early universe, as predicted by the Big Bang...
A spectrum that shows all colors of the rainbow without any gaps is...
If the universe were contracting instead of expanding, what would we...
The "Cosmological Redshift" is caused by galaxies moving through space...
How does the temperature of the Cosmic Microwave Background (CMB)...
An ________ spectrum consists of dark lines superimposed on a...
If a galaxy's spectral lines are shifted significantly more than...
The discovery of the CMB was accidental, found by researchers using a...
Which type of spectrum is produced by a hot, low-density gas?
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