Astronomy Lecture Review: Stars, Galaxies, and the Universe

Flashcards covering key astronomical concepts from Chapter 1 Introduction, Chapter 2 Say Black Dwarf, Chapter 3 Know the Difference, Chapter 4 Know of Singularity, Chapter 5 Things or Things, Chapter 6 Become Different Things, Chapter 7 Know the Time, and Chapter 8 Conclusion, focusing on stars, galaxies, and the universe.

Our galaxy, approximately 100,000 light years wide and 10,000 light years thick, shaped as a spiral.

Milky Way Galaxy

Binary Stars

Two stars paired up, where the center of balance in their system is closer to the more massive star.

Protostar

The beginning stage of a star's life, lasting approximately 10% of its total lifespan, before it reaches 10,000,000 Kelvin and starts hydrogen fusion.

Main Sequence Star

The adult life stage of a star, lasting approximately 90% of its total lifespan, characterized by hydrogen fusion at its core and a balance between outward expansion and inward gravitational pull.

Star Mass Classification (Low Mass)

Stars with less than 0.5 solar masses, which typically never fuse helium and end their lives as White Dwarfs.

Star Mass Classification (Medium Mass)

Stars with 0.5 to 8 solar masses, which can fuse hydrogen and helium, bloating into Red Giants before shedding a planetary nebula and becoming a White Dwarf.

Star Mass Classification (High Mass

8-20 Solar Masses; Stars in this range that evolve into Super Red Giants, explode as Supernovas, and collapse to form Neutron Stars.

Star Mass Classification (extremely High Mass)

>20 Solar Masses; Stars in this range that evolve into Super Red Giants, explode as Supernovas, and collapse to form Black Holes.

White Dwarf

The dense, hot remnant of low to medium mass stars (up to 8 solar masses) after they have shed their outer layers; considered a 'death' state, though not the ultimate end.

Black Dwarf

The theoretical ultimate death state of a star when a White Dwarf has completely cooled down and exhausted all its energy, though no star is currently old enough to have reached this stage.

Red Giant

A large, luminous star of intermediate to high mass in a late phase of stellar evolution, characterized by its bloated size and a cooler, reddish surface.

Supernova

A powerful and luminous stellar explosion, representing the true death of a massive star, briefly becoming one of the brightest objects in the night sky before collapsing into a neutron star or black hole.

Neutron Star

An extremely dense, compact remnant of a high-mass star (8-20 solar masses) after a supernova, formed by cramming protons and electrons together to create neutrons; still produces energy through magnetic fields and pulsars.

Black Hole

A region of spacetime where gravity is so strong that nothing, including light, can escape; formed from the collapse of very high-mass stars (>20 solar masses) after a supernova, characterized by extreme density.

Primordial Black Hole

A hypothetical type of black hole believed to have formed in the early universe, potentially differing in density and properties from stellar-mass black holes.

Singularity (Cosmology)

Refers to the initial point of the Big Bang, from which the universe began its expansion.

Elliptical Galaxy

One of the four main types of galaxies, accounting for 60% of observed galaxies, characterized by their elliptical shape and often red or yellow appearance; they are the largest type of galaxy.

Irregular Galaxy

One of the four main types of galaxies, accounting for 10% of observed galaxies, characterized by lacking a distinct regular shape.

Spiral Galaxy

One of the four main types of galaxies, accounting for 10% of observed galaxies, characterized by a pinwheel-like shape with distinct spiral arms, such as the Milky Way.

Barred Spiral Galaxy

One of the four main types of galaxies, accounting for 20% of observed galaxies, which is a spiral galaxy with a central bar-shaped structure composed of stars.

Dwarf Galaxy

Any extremely small or 'runted' galaxy, regardless of its specific shape (elliptical, irregular, or spiral).

Red Shift

The phenomenon where light waves from celestial objects moving away from an observer are stretched to longer (redder) wavelengths, indicating an expanding universe.

Blue Shift

The phenomenon where light waves from celestial objects moving towards an observer are compressed to shorter (bluer) wavelengths.

Venus

The brightest object in the nighttime sky (after the Moon and Sun), often called the 'morning star' or 'Lucifer star,' which reflects light rather than producing its own.

Star Colors and Temperature

Indicates stellar temperature, with blue being the hottest, followed by white, yellow, orange, and red as the coolest.

Rings on Planets

Characteristic possessed by all ice and gas giant planets (Jupiter, Saturn, Uranus, Neptune), and also by the dwarf planet QR.

Miranda

A moon of Uranus, notable for its unique and heavily scarred surface.

Dwarf Planets

A category of celestial bodies that are massive enough to be spherical but have not cleared their orbital path of other debris; examples include Ceres, Pluto, Eris, Makemake, Haumea, and Charon.

Ceres

A dwarf planet located within the asteroid belt.

Charon

Often considered a dwarf planet in its own right, orbiting Pluto, or classified as Pluto's largest satellite.

Ganymede

The largest moon of Jupiter, and indeed the largest moon in the Solar System, even exceeding the size of the planet Mercury, but still classified as a satellite rather than a planet.