The universe developed from a tiny speck (hypothetically containing the entirety of space) into something much, much bigger. Cosmic inflation explains how this occurred uniformly in spite of the rapidness of the process.

Gravity is one of the universe's fundamental forces and dominates every moment of our conscious experience. It keeps us close to the ground, drags baseballs and basketballs out of the air and gives our muscles something to struggle against. Cosmically, gravity is just as consequential.

Optical astronomy refers to an area of astronomy where astronomers observe and analyze light from the Universe that falls within the wavelength range that the human eye is sensitive to, using telescopes.

A nebula is a giant cloud of dust and gas in space. Nebulae exist in the space between the stars—also known as interstellar space. The closest known nebula to Earth is called the Helix Nebula.

A cosmological model is a mathematical description of the Universe that attempts to explain its current behaviour and evolution over time. Cosmological models are based on direct observations.

Relativity is the notion that the laws of physics are the same everywhere. We here on Earth obey the same laws of light and gravity as someone in a far-off corner of the universe.

Astroparticle physics looks at the most basic building blocks in nature to learn more about how they work. By studying particles from the universe we can learn more about how it was formed and hopefully start to answer big questions

Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution.

Quantum cosmology is the attempt in theoretical physics to develop a quantum theory of the Universe. This approach attempts to answer open questions of classical physical cosmology, particularly those related to the first phases of the universe.

Stellar dynamics is the branch of astrophysics which describes the collective motions of stars subject to their mutual gravity in a statistical way. That is, it describes systems of many point mass particles whose mutual gravitational interactions determine their orbits.