A system of stars, gas, dust, and dark matter bound together by gravity is called -

• an asteroid
• a nebula
• a galaxy
• a moon

Stars are made mostly of which two elements?

• Selenium and sodium
• Astatine and arsenic
• Chlorine and cesium
• Hydrogen and helium

A large celestial body made of gases that emits light due to nuclear reactions is called -

• a galaxy
• a nebula
• a comet
• a star 

An interstellar cloud of dust and gases that serves as a location for the formation of new stars is -

• a meteor
• a planet
• a galaxy
• a nebula

Galaxies are classified into all of the following types by their shapes EXCEPT -

• spiral
• elliptical
• oblong
• crescent

The Hertzsprung-Russell diagram is provided, which is used for classifying stars based on the relationship between their brightness and their temperature and color. Regulus belongs in which of the following classifications?

• Super Giants
• Giants
• Main Sequence Stars
• White Dwarfs

Which of the following is an accurate description of the relationship between components of the universe?

• Stars always contain galaxies
• Galaxies contain many stars
• Stars contain several nebulae
• Nebulae contain many galaxies

A characteristic of a nebula is that it -

• is at the center of the solar system
• is a region where stars are born
• forms halfway through a star's life cycle
• has the coolest temperature in space

Hot clouds of gaseous elements and compounds that act as nurseries for stars

• Galaxies
• Star
• Nebulae
• Black holes

Large objects that form dense gravity wells in space

• Galaxies
• Star
• Nebulae
• Black holes