Astronomy

Fact

A scientific observation accepted as true based on repeated evidence, but not absolute due to potential new evidence.

Hypothesis

A testable explanation for an observation, serving as a starting point for further investigation.

Law

A description of a natural behavior pattern, often in mathematical form, detailing how something occurs without explaining why.

Theory

A well-substantiated explanation of a natural aspect, built on facts, hypotheses, and laws, and subject to testing and refinement.

Galaxy

A vast, gravitationally bound system of stars, gas, dust, and dark matter, such as the Milky Way.

Local Group

The collection of galaxies that includes the Milky Way and Andromeda, along with smaller galaxies.

Milky Way Galaxy

The spiral galaxy that contains our solar system.

Observational science

A branch of science relying on observations and data from the natural world, exemplified by astronomy.

Planet

A celestial body orbiting a star, massive enough to be rounded by its own gravity, and has cleared its orbital neighborhood.

Planetary system

A system of planets and other objects orbiting a star.

Proxima Centauri

The nearest star to the Sun, located approximately 4.3 light-years away.

Solar system

The system consisting of the Sun and the objects that orbit it, including planets and comets.

Star

A luminous celestial body made of plasma, generating energy through nuclear fusion.

Star clusters

Groups of stars that are gravitationally bound and formed from the same molecular cloud.

Superclusters

Large structures in the universe made up of groups and clusters of galaxies.

Telescope

An instrument that collects and focuses electromagnetic radiation to observe distant celestial objects.

Universe

The entirety of space and time, including all forms of energy, matter, planets, stars, and galaxies.

Virgo Supercluster

The supercluster containing the Local Group, spanning about 110 million light-years.

Light-year

A unit of distance representing how far light travels in one year, crucial for understanding astronomical distances.

Scientific Method

The process of making observations, formulating hypotheses, and testing them through further inquiry.

Cosmological Principle

The assumption that physical laws observed on Earth apply universally throughout the universe.