Properties of Light & Spectroscopy
What property counts how many light waves pass a point in one second?
Frequency
What is the stretching or squishing of waves from a moving object called?
Doppler Effect
What did Edwin Hubble discover about almost all distant galaxies?
They are redshifted and moving away
Which element was found in the Sun's light before it was found on Earth?
Helium
How old is the universe according to modern evidence?
13.8 billion years
What causes dark absorption lines in starlight spectra?
Elements absorbing specific light colors
What does a "redshift" in a galaxy's light tell us?
It is moving away from Earth
According to Hubble's Law, what happens as a galaxy's distance increases?
It moves away faster
What were the element percentages right after the Big Bang?
92% Hydrogen / 8% Helium
What form does leftover Big Bang energy take today?
Cold microwave static
How are light frequency and wavelength related?
As frequency increases, wavelength gets shorter
Which visible light color has the longest wavelength?
Red
In the expanding balloon model, what do the dots represent?
Galaxies
What process inside stars turns hydrogen into helium?
Nuclear fusion
What temperature is the Cosmic Background Radiation today?
About 3 degrees K - 4 degrees K
Why are high-energy waves like gamma rays called "ionizing"?
They can knock electrons out of atoms
Besides galaxy motion, what else causes starlight to redshift?
Space stretching between galaxies
Why is an inflating balloon only a rough model for expanding space?
A balloon surface is 2D, but space is 3D
Which small, slow-burning stars are the oldest in the universe?
Red Dwarfs
If space is expanding today, what was the early universe like?
A single, tiny, hot point
What is the speed of light in empty space?
186,000 miles/sec (300,000 km/sec)
What happens to light waves when an object moves toward you?
They squish together (blueshift)
If you double your distance from a star, how bright does it look?
1/4 or a quarter as bright
How do giant stars compare to red dwarfs in lifespan?
Giant stars burn fuel fast and die quickly
Which atmospheric gases protect Earth by absorbing harmful radiation?
Water vapor, CO2, and Ozone