Comprehensive Astronomy: Moon, Eclipses, Solar System, Stars, Galaxies

What is astronomy?

The study of the universe, the stars, and the planets, combining aspects of math and physics.

What theory explains the origin of the Moon?

The impact theory, which suggests a Mars-sized meteoroid crashed into Earth, forming the Moon from debris.

What is the diameter of the Moon compared to Earth?

The Moon is ¼ the diameter of Earth.

What are lunar maria?

Dark areas on the Moon's surface formed by lava, making basalt rock.

What are lunar highlands?

Lighter rock areas on the Moon that contain mountain ranges and craters.

What are craters on the Moon?

Circular holes formed by the impact of meteoroids.

What is regolith?

A mix of small rock pieces formed from the impact of meteoroids, which can be 2-20m deep.

How long does it take for the Moon to complete one rotation and revolution?

27.3 days.

What is a spring tide?

When the sun and moon are aligned, causing extreme tides.

What is a neap tide?

When the sun and moon are at 90 degrees from each other, causing smaller tides.

What occurs during a lunar eclipse?

Earth comes between the Sun and the Moon, blocking sunlight from reaching the Moon.

How many types of lunar eclipses are there?

Two types: total and partial.

What happens during a solar eclipse?

The Moon moves between the Sun and Earth, casting a shadow on Earth.

What are the three types of solar eclipses?

Total, partial, and annular.

What is the solar system?

One star (the Sun) and the planets that revolve around it.

What is the nebular theory?

An explanation for the formation of the solar system from a rotating cloud of gas and dust.

What is nuclear fusion?

A nuclear reaction in which hydrogen atoms fuse to form helium, releasing tremendous energy.

What are the inner planets also known as?

The terrestrial planets.

Which planets are classified as gas giants?

Jupiter, Saturn, Uranus, and Neptune.

What defines a dwarf planet?

An object orbiting the Sun that is round due to its gravity, has not cleared its orbit, and is not a satellite.

What are comets made of?

Dust particles mixed with water, carbon dioxide, methane, and ammonia.

What is the difference between a meteoroid, meteor, and meteorite?

A meteoroid is a fragment in space, a meteor is the light produced when it burns in the atmosphere, and a meteorite is what survives and strikes Earth's surface.

What is electromagnetic radiation?

Energy that travels in waves, including visible light, radio waves, and x-rays.

What is the speed of light?

Approximately 300,000,000 meters per second.

What happens to light when it passes through a prism?

It is refracted into a spectrum of colors.

What is the electromagnetic spectrum?

A continuum of different types of electromagnetic radiation, including visible light.

What device do astronomers use to analyze light from stars?

A spectroscope.

What is the Doppler Effect?

The apparent change in frequency of waves caused by the relative motion of the source and observer.

What does redshift indicate about a star's movement?

The star is moving away from Earth.

What does blueshift indicate about a star's movement?

The star is moving toward Earth.

What is an Astronomical Unit (AU)?

The distance between Earth and the Sun, approximately 150 million km.

What is a light year?

The distance that light travels in one year, about 9.46 trillion kilometers.

How is a star's mass typically expressed?

As multiples of the mass of the Sun.

What color indicates a very hot star?

Blue.

What is luminosity?

The actual brightness of a star.

What is apparent magnitude?

The brightness of a star as it appears from Earth.

What is absolute magnitude?

The true brightness of a star if all were at the same distance from Earth.

What does a Hertzsprung-Russell Diagram show?

The relationship between a star's absolute magnitude and temperature.

What is a main-sequence star?

A star that is actively fusing hydrogen into helium, making up about 90% of stars.

What is a red giant?

A large, cool, very bright star occupying the upper-right portion of the H-R Diagram.

What is a supergiant star?

An extremely large and bright star, over 100 times the diameter of the Sun.

What is a white dwarf?

A hot, low-brightness star that is near the end of its life cycle.

What is a protostar?

A collapsing cloud of gas and dust that is destined to become a star.

What happens during the red-giant stage of a star's life?

The star's outer envelope expands and cools, turning red.

What occurs during the death of low-mass stars?

They collapse into a white dwarf after exhausting their hydrogen fuel.

What is a supernova?

An exploding massive star that increases in brightness many thousands of times.

What is a neutron star?

A star of extremely high density composed entirely of neutrons, often a remnant of a supernova.

What is a black hole?

A massive star that has collapsed to a point where its gravity prevents anything, including light, from escaping.

What is the Big Bang Theory?

The theory that the universe began from a hot, dense state and has been expanding ever since.

What evidence supports the Big Bang Theory?

The redshift of galaxies and cosmic background radiation.

What are the three types of galaxies?

Spiral, elliptical, and irregular.

What is the Milky Way?

Our galaxy, which is classified as a spiral galaxy.