Astronomy Study Guide

A set of vocabulary flashcards covering key concepts in astronomy, including definitions for terms related to celestial bodies, star formation, planets, and moon phases.

Meteor

A small celestial body made of rock and dust, smaller than 10 meters long. When it hits Earth, it is called a meteorite.

Asteroid

A celestial object made of rock and dust, at least 10 meters long, found in the Asteroid Belt. Some asteroids may have their own moons.

Comet

An icy celestial object made of dust and rock, known for its two tails: an ionized gas tail and a dust tail. Comets are found in the Kuiper Belt and the Oort Cloud.

Nebula

A giant cloud of gas and dust in space where stars are formed, also referred to as a star nursery.

Fusion

The process by which stars combine hydrogen atoms into helium atoms, which occurs during star formation.

White Dwarf

A small, dense star that represents the remnant of a star that has exhausted its nuclear fuel.

Red Giant

A large star that has expanded and cooled after exhausting hydrogen in its core, resulting in a red appearance.

Blue Giant

A very hot and bright star that is much larger than the Sun.

Rotation

The action of a planet spinning 360 degrees on its axis, determining the length of a day and night cycle.

Revolution

The time taken for a planet to complete one orbit around its star, determining the length of a year.

Antegrade

The apparent forward motion of a planet as it moves towards Earth.

Retrograde

The apparent backward motion of a planet as it moves away from Earth.

Phases of the Moon

The eight stages of the moon's appearance, including new moon, waxing crescent, waxing quarter, waxing gibbous, full moon, waning gibbous, waning quarter, and waning crescent.

What is the composition of a comet?

Comets are primarily composed of ice, dust, and rocky material, often described as 'dirty ice' due to their mixed composition.

How do comets form?

Comets originate from the Kuiper Belt and Oort Cloud, forming from the remnants of the early solar system's formation process.

What are the two main components of a comet's tail?

A comet's tail consists of an ion tail made of charged gas particles and a dust tail comprised of small dust particles.

What is the difference between meteoroids, meteors, and meteorites?

Meteoroids are smaller than asteroids and travel in space; when they enter the Earth's atmosphere and burn up, they are called meteors; if they reach the Earth's surface, they are called meteorites.

What are the two main types of asteroids?

Asteroids can be classified into two main types: C-type (carbonaceous) and S-type (silicate). C-type are dark and carbon-rich, while S-type are made up of metal and silicate.

What is the difference between a star and a planet?

Stars are massive celestial bodies that generate light through nuclear fusion, while planets are smaller bodies that do not produce their own light and orbit stars.

How does the Hertzsprung-Russell diagram classify stars?

The Hertzsprung-Russell diagram classifies stars based on their luminosity and temperature, separating them into categories such as main sequence, giants, and supergiants.

What is a supernova?

A supernova is a powerful and luminous explosion that occurs at the end of a star's life cycle, leading to the dispersal of its outer layers into space.

What is a neutron star?

A neutron star is the remnant core of a massive star that has exploded in a supernova, composed almost entirely of neutrons and extremely dense.

What role does gravity play in star formation?

Gravity causes gas and dust in a nebula to collapse and clump together, eventually leading to the formation of stars.

What is the lifespan of a typical star like the Sun?

A typical star like the Sun has a lifespan of about 10 billion years, spending around 90% of that time in the main sequence phase.

What happens during the red giant phase of a star?

During the red giant phase, a star expands and cools after exhausting hydrogen in its core, leading to a fusion of helium into heavier elements.

What is the fate of massive stars after the supernova?

After a supernova, massive stars may become neutron stars or black holes, depending on their mass.

What distinguishes a blue giant from a red giant?

Blue giants are hotter, larger, and more luminous than red giants and are typically in a more advanced stage of stellar evolution.

What is a rogue planet?

A rogue planet is a planetary body that does not orbit a star and instead wanders through space on its own.

What is the Kuiper Belt?

The Kuiper Belt is a region beyond Neptune populated by many small, icy bodies, including dwarf planets and comets.

What is an asteroid belt?

An asteroid belt is a region in space, primarily between Mars and Jupiter, where a large number of asteroids are found orbiting the Sun.

How do asteroids differ from comets in composition?

Asteroids are primarily made of rock and metal, while comets contain significant amounts of ice and dust.

What is a brown dwarf?

A brown dwarf is a substellar object that is not massive enough to sustain hydrogen fusion in its core, often referred to as a 'failed star.'

How do stars become supergiants?

Stars become supergiants after exhausting their hydrogen fuel and undergoing nuclear fusion of heavier elements, significantly increasing their size and luminosity.