Unit 6:Universe

Flashcards covering the chemical composition of the human body and universe, the timeline of the Big Bang, star formation, and galaxy classification.

Four most common elements in the Human Body

Hydrogen, Oxygen, Carbon, and Nitrogen.

Five most common elements in the Universe

Hydrogen, Helium, Oxygen, Carbon, and Nitrogen.

Helium

The second most common element in the universe; as a Noble Gas, it generally only bonds with itself.

The Big Bang

An event occurring about $13.8$ billion years ago where the universe originated from an extremely hot, dense point.

10^{-34} seconds

The age of the universe when it experienced a period of rapid inflation and expansion.

1 second after the Big Bang

The point in time when the universe began to cool and matter (protons, neutrons, electrons, anti-electrons, photons, neutrinos) began to form.

Temperature range of element formation

The universe cooled from $100$ nonillion ($10^{32}$) Kelvin to $1$ billion ($10^9$) Kelvin as the first elements formed.

Hydrogen and Helium

The first two elements to form in the cooling universe following the Big Bang.

Cosmic microwave background radiation

The initial flash of light from the Big Bang that can be detected today, released when the universe was around $380,000$ years old.

400 million years

The approximate time after the Big Bang when gas began to clump together to form the first galaxies and stars.

Red Shift

Evidence for the expansion of the universe occurring when an object moves away from an observer, resulting in longer frequencies of light that appear red.

Blue Shift

A phenomenon where an object moving towards an observer creates shorter frequencies of light, making the object appear blue.

Nebula

A cloud of gas and dust that serves as the starting point for the birth of a star.

Critical density for star ignition

Approximately $5,000$ Hydrogen molecules per cubic centimeter ($cm^3$).

Nuclear fusion

The process that fuels a star, specifically by fusing Hydrogen into Helium and releasing large amounts of energy.

The Sun

Our star, formed about $4.6$ billion years ago, which accounts for $99.8\%$ of the mass of the entire solar system.

Galaxy

A large group of millions to billions of stars, gas, and dust held together by gravity.

Edwin Hubble

The scientist who, in $1926$, developed classifications for galaxies based on their morphology or appearance.