Unit 4: Our Universe Retake

Front

What is a galaxy?

Back

A galaxy is a massive system that consists of stars, stellar remnants, interstellar gas, dust, and dark matter, bound together by gravity. An example is the Milky Way.

Front

What is a solar system?

Back

A solar system is a collection of celestial bodies, including a star and the objects that orbit it, such as planets, moons, asteroids, and comets. Our solar system includes the Sun and its orbiting planets.

Front

What is a star?

Back

A star is a luminous celestial body made of plasma, primarily hydrogen and helium, undergoing nuclear fusion. Examples include the Sun and Proxima Centauri.

Front

What is a light year?

Back

A light year is the distance that light travels in one year, approximately 9.46 trillion kilometers (5.88 trillion miles). It is used to measure astronomical distances.

Front

What is the composition of stars?

Back

Stars are primarily composed of helium and hydrogen, which are the two lightest and most abundant elements in the universe.

Front

What is the astronomical unit (AU)?

Back

An astronomical unit (AU) is a standard unit of measurement used in astronomy, defined as the average distance between the Earth and the Sun, approximately 149.6 million kilometers.

Front

How does distance affect the appearance of stars?

Back

As distance increases, stars appear smaller and dimmer. For example, from a planet near Proxima Centauri, the Sun would look like a dot in the sky.

Front

What is the nearest star to Earth after the Sun?

Back

Proxima Centauri is the nearest star to Earth after the Sun, located about 4.24 light-years away.

Front

What is the significance of measuring distances in light years?

Back

Measuring distances in light years allows astronomers to express vast distances in space in a more comprehensible way, as space is incredibly large.

Front

What are the main components of the universe?

Back

The main components of the universe include galaxies, stars, planets, moons, asteroids, comets, and dark matter.