Cosmic Scale and Light: Key Concepts

A set of flashcards summarizing key vocabulary and concepts related to cosmic scale, astronomy, and the nature of light as discussed in the lecture.

Light-year

A unit of distance that represents how far light travels in one year, approximately 5.88 trillion miles.

Spectroscopy

The study of the interaction between matter and electromagnetic radiation, used to analyze the light emitted or absorbed by substances.

Blackbody Radiation

The theoretical spectrum of light emitted by an idealized object that absorbs all radiation hitting it, used to describe temperature versus wavelength relationships.

Exoplanets

Planets that orbit stars outside our solar system, whose discovery has changed our understanding of planetary formation and the likelihood of extraterrestrial life.

Electromagnetic Communication Limits

The delays in communication that occur because light and radio waves travel at finite speeds, meaning distant messages take time to arrive.

Hydrogen Spectrum Lines

Specific wavelengths at which hydrogen emits or absorbs light, most notably at 121.6 nm in the ultraviolet range.

Milky Way

Our galaxy, which contains roughly a billion stars and is located about three-quarters of the way out from its center.

Virgo Cluster

A large cluster of galaxies that is part of our local supercluster, providing context to the three-dimensional structure of the universe.

Cosmic Context

The understanding of our place in the universe, emphasizing that Earth is not unique and that we inhabit only a small portion of the vast observable universe.

Planet Formation

The process by which planets develop from the dust and gas surrounding young stars, often considered a natural byproduct of star formation.

Light-year

A unit of distance that represents how far light travels in one year, approximately 5.88 trillion miles.

Spectroscopy

The study of the interaction between matter and electromagnetic radiation, used to analyze the light emitted or absorbed by substances.

Blackbody Radiation

The theoretical spectrum of light emitted by an idealized object that absorbs all radiation hitting it, used to describe temperature versus wavelength relationships.

Exoplanets

Planets that orbit stars outside our solar system, whose discovery has changed our understanding of planetary formation and the likelihood of extraterrestrial life.

Electromagnetic Communication Limits

The delays in communication that occur because light and radio waves travel at finite speeds, meaning distant messages take time to arrive.

Hydrogen Spectrum Lines

Specific wavelengths at which hydrogen emits or absorbs light, most notably at 121.6 nm in the ultraviolet range.

Milky Way

Our galaxy, which contains roughly a billion stars and is located about three-quarters of the way out from its center.

Virgo Cluster

A large cluster of galaxies that is part of our local supercluster, providing context to the three-dimensional structure of the universe.

Cosmic Context

The understanding of our place in the universe, emphasizing that Earth is not unique and that we inhabit only a small portion of the vast observable universe.

Planet Formation

The process by which planets develop from the dust and gas surrounding young stars, often considered a natural byproduct of star formation.

Electromagnetic Spectrum

The full range of electromagnetic radiation, from radio waves to gamma rays, characterized by different wavelengths and frequencies.

Doppler Effect (Astronomical)

The change in wavelength or frequency of light or sound waves as the source and observer move towards or away from each other, used to determine the radial velocity of celestial objects.

Habitable Zone

The region around a star where conditions, specifically temperature, could allow liquid water to exist on a planet's surface, considered crucial for life as we know it.

Dark Matter

A hypothetical form of matter that does not interact with electromagnetic radiation, making it undetectable by light, but whose presence is inferred from its gravitational effects on visible matter.

Big Bang Theory

The prevailing cosmological model describing the universe's earliest known periods, stating that the universe expanded from an extremely hot, dense state billions of years ago.

Light-year

A unit of distance that represents how far light travels in one year, approximately 5.88 trillion miles.

Spectroscopy

The study of the interaction between matter and electromagnetic radiation, used to analyze the light emitted or absorbed by substances.

Blackbody Radiation

The theoretical spectrum of light emitted by an idealized object that absorbs all radiation hitting it, used to describe temperature versus wavelength relationships.

Exoplanets

Planets that orbit stars outside our solar system, whose discovery has changed our understanding of planetary formation and the likelihood of extraterrestrial life.

Electromagnetic Communication Limits

The delays in communication that occur because light and radio waves travel at finite speeds, meaning distant messages take time to arrive.

Hydrogen Spectrum Lines

Specific wavelengths at which hydrogen emits or absorbs light, most notably at 121.6 nm in the ultraviolet range.

Milky Way

Our galaxy, which contains roughly a billion stars and is located about three-quarters of the way out from its center.

Virgo Cluster

A large cluster of galaxies that is part of our local supercluster, providing context to the three-dimensional structure of the universe.

Cosmic Context

The understanding of our place in the universe, emphasizing that Earth is not unique and that we inhabit only a small portion of the vast observable universe.

Planet Formation

The process by which planets develop from the dust and gas surrounding young stars, often considered a natural byproduct of star formation.

Electromagnetic Spectrum

The full range of electromagnetic radiation, from radio waves to gamma rays, characterized by different wavelengths and frequencies.

Doppler Effect (Astronomical)

The change in wavelength or frequency of light or sound waves as the source and observer move towards or away from each other, used to determine the radial velocity of celestial objects.

Habitable Zone

The region around a star where conditions, specifically temperature, could allow liquid water to exist on a planet's surface, considered crucial for life as we know it.

Dark Matter

A hypothetical form of matter that does not interact with electromagnetic radiation, making it undetectable by light, but whose presence is inferred from its gravitational effects on visible matter.

Big Bang Theory

The prevailing cosmological model describing the universe's earliest known periods, stating that the universe expanded from an extremely hot, dense state billions of years ago.

Hubble's Law

The observation that galaxies are moving away from the Earth at speeds proportional to their distance, providing evidence for the expansion of the universe (v = H_0 imes d).

Cosmic Microwave Background (CMB)

Leftover radiation from the Big Bang, detectable as a faint glow across the universe, providing strong evidence for the Big Bang theory.

Nebulae

Interstellar clouds of dust, hydrogen, helium, and other ionized gases; they are often star-forming regions.

Supernova

A powerful stellar explosion that occurs at the end of a star's life, briefly outshining an entire galaxy and radiating as much energy as the Sun is expected to emit over its entire life span.

Quasars

Extremely luminous active galactic nuclei, powered by supermassive black holes at the centers of distant galaxies, representing some of the most energetic phenomena in the universe.