Edwin Hubble, Doppler Shift, and the Expanding Universe

The video tutorial discusses Edwin Hubble's contributions to astronomy, including the categorization of galaxies and the discovery that the universe is expanding. It explains the history of astronomy, the realization of galaxies beyond the Milky Way, and the Doppler effect's role in understanding redshift. Hubble's observations led to the formulation of Hubble's law, which describes the relationship between a galaxy's distance and its recession velocity, providing evidence for the Big Bang theory.

What major shift in understanding about our universe occurred before the 20th century?

• The center of the universe was found to be the sun.

• The Earth was discovered to be flat.

• Stars were found to be made of water.

• The universe was discovered to be infinite.

What did Edwin Hubble contribute to the field of astronomy?

• He discovered the first planet outside our solar system.

• He proved the Earth is round.

• He developed the categories and subcategories of galaxies.

• He invented the telescope.

What is the Doppler effect?

• A phenomenon where light waves change color.

• A technique to calculate the mass of galaxies.

• A change in wave frequency due to the motion of the source.

• A method to measure the temperature of stars.

What does a redshift in a galaxy's light spectrum indicate?

• The galaxy is stationary.

• The galaxy is moving away from us.

• The galaxy is changing shape.

• The galaxy is moving towards us.

What did Hubble's observations about galaxy movement suggest about the universe?

• The universe is static.

• The universe is expanding.

• The universe is shrinking.

• The universe is contracting.

According to Hubble's Law, what is the relationship between a galaxy's distance and its recession velocity?

• Distance and velocity are unrelated.

• The farther a galaxy, the faster it moves away.

• The closer a galaxy, the faster it moves away.

• The closer a galaxy, the slower it moves away.

What is the Hubble constant used for?

• To measure the mass of galaxies.

• To calculate the age of stars.

• To find the temperature of planets.

• To determine the distance to galaxies.