Student
Exploration: Big
Bang Theory –
Hubble’s Law
2021 (answered)
, Name: Shelby Fisher Date: 10/07/2021
Student Exploration: Big Bang Theory – Hubble’s Law
Directions: Follow the instructions to go through the simulation. Respond to the questions and
prompts in the orange boxes.
Vocabulary: absolute brightness, absorption spectrum, apparent brightness, Big Bang theory, blueshift,
Cepheid variable, Doppler shift, Hubble constant, Hubble’s law, luminosity, megaparsec, period, redshift,
spectrograph
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
Standing by the side of a lonely highway at night, you see two motorcycle headlights, one in each direction.
The headlight on your left appears brighter than the one on your right.
1. If the headlights are equally bright, which motorcycle is closer? The one on the left
Explain: If the light that you are seeing is brighter that means that they are closer to you than the
other motorcycle.
2. Suppose the dim-looking headlight on the right is actually a small light on the front of a bicycle. What can
you conclude about the distance of the motorcycle and bicycle?
The motorcycle covers more distance than the bicycle.
Gizmo Warm-up
In 1912, an astronomer named Henrietta Swan Leavitt
studied a class of stars called Cepheid variables. These
stars change from bright to dim to bright again. Her
discoveries led to a method of measuring distances to
other galaxies and eventually helped to support the Big
Bang theory of the origin of the universe.
In the Big Bang Theory – Hubble’s Law Gizmo, select Region A.
Look at the image of the Andromeda Galaxy, a galaxy relatively close to our own Milky Way galaxy.
1. Locate the two Cepheid variables, the stars that change in brightness over time. Star A-091 is the yellow
star, and A-171 is the white star.
A. Which star reaches a greater apparent brightness? A-091
B. Which star takes longer to pulse? A-091
2. Because both stars are in the same galaxy, they are about the same distance from Earth. Based on what
you see, how is the brightness of the star related to how quickly it pulses?
The brighter the star, the more time it takes to pulse.