A Modern View of the Universe

These flashcards cover key concepts and vocabulary related to the structure, scale, and history of the universe as outlined in the lecture notes.

Cosmic Address

The hierarchical structure encompassing Earth, the solar system, the Milky Way Galaxy, and the larger universe.

Galaxy

A large island of stars in space, typically containing hundreds of millions to trillions of stars, bound together by gravity.

Astronomical Unit (AU)

The average distance from the Earth to the Sun, approximately 150 million kilometers (93 million miles).

Light-Year (LY)

The distance that light travels in one year, approximately 9.46 trillion kilometers (6 trillion miles).

Superclusters

Regions in the universe where galaxies and galaxy clusters are densely packed together.

Observable Universe

The portion of the universe that can be observed from Earth, limited by the speed of light and the age of the universe.

The Big Bang

The event that marks the beginning of the universe, occurring approximately 14 billion years ago, leading to its ongoing expansion.

Dark Matter

A form of matter that does not emit, absorb, or reflect light, making it undetectable by conventional telescopes; it is thought to make up much of the universe's mass.

Expansion of the Universe

The increase in average distances between galaxies over time due to the universe's expansion.

The Cosmic Calendar

A way to visualize the history of the universe compressed into one year, where each month represents roughly a billion years.

Star

A large glowing ball of gas that generates heat and light through nuclear fusion in its core

Planet

A moderately large object that orbits a star and shines primarily by reflecting light from its star.

Moon

an object that orbits a planet

asteroid

small and rocky object that orbits a star

comet

small and ice-rich object that orbits a star

small solar system body

that is neither a planet nor a dwarf planet, often includes asteroids and comets.

solar system

The sun and all the material that orbits it including planets, dwarf planets, and small solar system bodies.

cluster/groups of galaxies

A collection of galaxies bound together by gravity, often containing hundreds or thousands of individual galaxies.

Universe/Cosmos

the sum of all matter, energy, planets, stars, galaxies, and the physical laws governing them.

Rotation

The spinning of an object around its axis

Orbit (revolution)

The path an object takes around another object in space due to gravity, completing one full revolution in a specific time period.