Exit Check 8.7: The Big Bang

Front

The universe is ____________ years old.

Back

13.7 billion

Front

A galaxy is found in the night sky. The hydrogen spectrum of this galaxy is shifted such that the red spike in the emission spectrum is at a wavelength 30 nm larger than the expected wavelength of 660 nm. How fast is that galaxy moving?

Back

Front

The Cosmic Background Radiation is:

Back

the remaining energy from the big bang.

Front

Galaxies that are redshifted are:

Back

moving away from us.

Front

Why is the Cosmic Background Radiation also known as the surface of last scattering?

Back

Photons moving in the early universe were scattered by electrons making the universe opaque and glowing. When it cooled enough to form hydrogen that last light traveled out as the CMB.

Front

What is redshift?

Back

The phenomenon where light from an object moving away from an observer is shifted to longer wavelengths.

Front

What does the term 'Big Bang' refer to?

Back

The event that marks the beginning of the universe, approximately 13.7 billion years ago.

Front

What is the significance of Cosmic Background Radiation?

Back

It provides evidence for the Big Bang theory and shows the early state of the universe.

Front

What is a galaxy?

Back

A massive system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity.

Front

What does it mean if a galaxy is blue-shifted?

Back

It indicates that the galaxy is moving towards us.