Finals Prep

Globular star clusters

Oldest discrete objects with reliably determined ages, thought to be about 12-13 billion years old.

Age of the Universe

Estimated to be about 14 billion years, based on the age of the oldest objects within it.

Hubble Time

Amount of time since the Big Bang, assuming a constant speed for any given galaxy.

Hubble's Constant (H₀)

The ratio of the recession speed (v) of a galaxy to its distance (d) from us.

Hubble Space Telescope Key Project

Aimed to obtain distances to important galaxies, but faced delays due to spherical aberration on its primary mirror.

Cosmological Principle

On the largest scales, the universe is very uniform, having the same average density in all directions.

Cosmological Constant

A postulated long-range repulsive force that Einstein initially believed kept the universe from contracting.

Closed Universe

A universe where average density exceeds critical density (Ω_M > 1), leading to eventual collapse or 'big crunch'.

Flat Universe

A universe where average density equals critical density (Ω_M = 1), leading to expansion that slows but never stops.

Open Universe

A universe where average density is less than critical density (Ω_M < 1), allowing for perpetual expansion.

Type Ia Supernova

Used for the most accurate distance measurements to determine the expansion of the universe.

Accelerating Universe

Observation shows that the universe is expanding at an increasing rate.

Dark Energy

A mysterious force that causes the expansion of space to accelerate.

Cosmic Microwave Background

A faint radio glow that pervades the universe, providing evidence for the Big Bang.

Primordial Nucleosynthesis

Formation of the nuclei of isotopes of hydrogen, helium, and lithium during the first minutes of the universe.

Drake Equation

An equation used to estimate the number of communicating civilizations in the Milky Way based on various factors.

Hubble-Lemaître Law

Describes the relationship between the recession velocity of a galaxy and its distance.

Leavitt’s Law

States that luminosity (L) of a Cepheid variable star is proportional to its period (P).

Cosmic Jerk

The rate of change of acceleration as the universe transitioned from deceleration to acceleration.

Exoplanet Detection Methods

Techniques such as the transit method and radial velocity most commonly used to find planets outside our solar system.

Astrobiology

Study of the potential for life elsewhere in the universe.

Friedmann Universes

Three scenarios of universe expansion possibilities derived from general relativity.

WIMPS (Weakly Interacting Massive Particles)

Exotic particles theorized to account for much of the dark matter in the universe.

Angular Resolution Formula

Mathematical relationship that describes the ability of a telescope to distinguish small details in an image.

Kepler's 3rd Law

Relation between the period of orbit (p in years) and the semi-major axis (a in AU), given by p² = a³.

Stefan-Boltzmann Law

Describes the power radiated by a black body in terms of its temperature; E/s/m² = σT⁴.

Doppler Effect

Change in frequency or wavelength of light from an object due to its motion towards or away from the observer.

Spectroscopic Parallax

Method to determine the distance to stars using their apparent brightness and spectra.

The Big Bang

The leading explanation for the origin of the universe, indicating it had a beginning and has been expanding ever since.

Baryonic Matter

Ordinary matter that makes up stars, planets, and living beings, constituting about 5% of the universe.

Cold Dark Matter

Non-luminous matter that interacts via gravity only, making up approximately 25% of the universe.

Dark Matter

Matter that does not emit light or energy, detectable through its gravitational effects on visible matter.

Einstein's Biggest Blunder

His introduction of the cosmological constant, which he later deemed unnecessary upon the discovery of the expanding universe.

Acceleration of Universe

The phenomenon where the rate of expansion of the universe is increasing.

Planets with Moons

Many planets, particularly gas giants like Saturn, host numerous moons.

Elementary Particles

Fundamental constituents of matter, including quarks and leptons.

Neutron Stars

Remnants of massive stars following a supernova explosion, extremely dense and composed mainly of neutrons.

Stelliferous Era

The current era in which stars are still forming and abundant.

Degenerate Era

Time in the future when stellar formation has ceased, filled with remnants like white dwarfs and neutron stars.

Black Hole Era

Future period when black holes will be the only remaining significant objects in the universe.

Dark Era

Final stage of the universe's evolution with only low-energy particles like neutrinos remaining.

Cosmic Evolution

Study of the universe's development from the Big Bang to its future states.

Spherical Aberration

Optical distortion due to an imperfect lens, affecting the performance of telescopes.

Gravitational Lensing

The bending of light from objects behind massive bodies, used to study dark matter.

CERN and FermiLab

Research institutions focused on particle physics, investigating the fundamental components of matter.

Rubin Observations

Pioneering studies demonstrating that galaxy rotational speeds imply the presence of dark matter.

Proper Motion

The apparent motion of a star across the sky as seen from Earth, important for understanding celestial mechanics.

Astrophysical Cosmology

The field of study that combines astrophysics with cosmology to understand the universe's large-scale structure.

Universal Expansion

The theory that the universe is continuously expanding, as evidenced by the redshift of distant galaxies.