Front

What is the whole universe?

Back

The entire cosmos, including all matter, energy, planets, stars, galaxies, and the contents of intergalactic space.

Front

What is the observable universe?

Back

The part of the universe that we can see or observe from Earth, limited by the speed of light and the age of the universe.

Front

What shape is the observable universe?

Back

The observable universe is generally considered to be flat based on current measurements.

Front

How big is the observable universe?

Back

Approximately 93 billion light-years in diameter.

Front

How old is the observable universe?

Back

About 13.8 billion years old.

Front

Why is the distance of the radius of the observable universe takes light 46.5 billion years to cross but the age of the observable universe shorter than that?

Back

Due to the expansion of the universe, the light has been travelling for 13.8 billion years, but the universe has expanded, making the observable universe larger.

Front

What are the two main key features the Big Bang theory suggests?

Back

The universe is expanding, and it originated from a hot, dense state.

Front

What are the two main evidences that support the Big Bang theory?

Back

Cosmic Microwave Background Radiation (CMB) and the redshift of galaxies.

Front

What does the redshift of the spectrums of stars and galaxies suggest?

Back

That the universe is expanding, as distant galaxies are moving away from us.

Front

What is the Doppler effect?

Back

A change in the frequency or wavelength of a wave in relation to an observer moving relative to the wave source.