Astronomy Quiz: Stars and Universe Concepts

The study of the physical properties and behavior of celestial objects using mathematical models.

The distance between the Earth and the Sun. This is a common unit of measurement for distances within our solar system.

Stellar parallax is a technique used for measuring the distance to stars by observing how their apparent positions change over time due to the Earth's movement around the Sun.

A cloud of ionized gas that emits light, often brightly.

A cloud of gas and dust that reflects light from nearby stars.

When a star's spectral lines shift towards the blue end of the spectrum, it indicates that the star is moving towards the observer.

A star whose brightness varies regularly over time.

A dense cloud of gas and dust that blocks light from passing through it.

Wien's Law states that the wavelength at which a blackbody emits the most radiation is inversely proportional to its temperature. This means hotter objects emit more radiation at shorter wavelengths (like blue light), while cooler objects emit more radiation at longer wavelengths (like red light).

Absorption lines are dark lines in a star's spectrum that occur when specific wavelengths of light are absorbed by atoms in the star's atmosphere. These absorbed wavelengths correspond to the energy levels of the atoms, creating unique 'fingerprints' that reveal the composition of the star.

The Big Bang theory suggests that the universe originated from a very hot and dense state and has been expanding ever since. During the early stages, the universe was filled with a hot plasma of particles. As the universe expanded and cooled, these particles began to combine, forming atoms. This process is called structure formation.

An open universe is one that will continue to expand forever. This occurs when the density of the universe is less than the critical density, meaning gravity isn't strong enough to overcome the expansion.

A main sequence star is in a stable state because the outward pressure from its internal nuclear fusion reactions is balanced by the inward pressure from gravity. This equilibrium maintains the star's shape and size for a long time.

M-class stars are the coolest stars, with temperatures ranging from about 2,400 to 3,700 Kelvin. This low temperature gives them a reddish hue, similar to the color of a dying ember.

Galileo observed the phases of Venus, which showed that Venus orbits the Sun, not the Earth. He also observed the moons of Jupiter, demonstrating that not all celestial objects revolve around the Earth. These observations supported the Copernican heliocentric model, where the Sun is the center of the solar system.

A white dwarf is the final stage of a star like our Sun. After the star has exhausted its fuel in the red giant phase, the core contracts to a very dense and hot sphere, about the size of the Earth. White dwarfs are slowly cooling and eventually will become black dwarfs, but this process takes billions of years.

A model where the Earth is at the center of the universe, with other celestial bodies orbiting around it.

A model where the Sun is at the center of the solar system, with the planets orbiting around it.

Small rocky objects that enter Earth's atmosphere and burn up due to friction with the air, creating a streak of light across the sky.

The remains of a meteor that survives its journey through Earth's atmosphere and reaches the ground.

The shape of a planet's orbit around a star, where the star is located at one of the foci of the ellipse.

The degree to which a planet's orbit deviates from a perfect circle. A higher eccentricity equates to a more elliptical orbit.

The inner planets of our solar system, composed mainly of solid rock and metal.

Small bodies of matter that existed in the early solar system and eventually coalesced into planets.

The earliest eon in Earth's history, characterized by extreme heat and volcanic activity. It is believed to have lasted from 4.5 to 4.0 billion years ago.

The process by which Earth's internal structure separated into distinct layers based on density, with denser materials sinking to the core and lighter materials forming the crust.

The principle that states geological processes occurring today are similar to those in the past.

The layer of the Sun that emits visible light, making it appear bright.

The outer layer of the Sun's atmosphere, characterized by extremely high temperatures and low density.

A celestial body that orbits a star, but is not a star itself. Exoplanets are found outside our solar system.

A type of exoplanet that is similar in size to Earth.

A type of exoplanet similar to Neptune, characterized by a gaseous composition and a large size.

The process by which the Earth's outer layer is divided into several plates that move and interact with one another.

A supercontinent that existed approximately 335 to 175 million years ago, encompassing almost all of the Earth's landmasses.

The period in Earth's history that witnessed the rapid diversification and appearance of many different types of organisms, particularly multicellular life.

The Ordovician period, known for its diverse and abundant marine invertebrates.

Jawed fish, a significant development in vertebrate evolution, were common during the Silurian period.

The Permian period, ending with a catastrophic mass extinction event known as "The Great Dying."

The study of the origin and structure of the Universe, including its evolution and physical properties.

Eratosthenes, a Greek scholar, was the first to accurately calculate the circumference of the Earth.

The apparent brightness of a star as seen from Earth, considering its intrinsic luminosity and distance from Earth.

The actual amount of light emitted by a star, independent of its distance from Earth.

The Stephan-Boltzmann Law states that the total energy radiated per unit area of a blackbody is proportional to the fourth power of its absolute temperature.

An absorption spectrum is produced when light passes through a cool gas, and specific wavelengths of light are absorbed by the gas atoms.

An emission spectrum is produced when hot gases emit light at specific wavelengths, creating bright lines in the spectrum.

A dark-line spectrum, also called an absorption spectrum, reveals the composition of a star. Each element absorbs specific wavelengths of light, creating dark lines in the spectrum that correspond to the element's unique fingerprint.

Gamma rays have the highest energy in the electromagnetic spectrum.