Components of the Universe

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DI Cha appears as a bright object visible in the Milky Way galaxy. DI Cha is a star system with three objects. Each object produces light and rotates on its own axis. Based on this information, the three objects that make up the DI Cha system are all -

• asteroid
• comets
• planets
• stars

Which statement best describes a galaxy?

• a cloud of gas that is the birthplace of stars
• system of billions of stars, gas, and dust held together by gravity
• a ball of plasma that experiences nuclear fusion in its core
• a mass of dust and ice that orbits a star in an elliptical pattern

Which of the following describes a star?

• star formation begins in a nebula
• white dwarfs become main-sequence stars when they gain mass
• supergiants are stars that can absorb black holes
• main-sequence stars are formed by comets

In December an object orbiting the sun seemed to disappear behind the sun. When a satellite did not detect the object, astronomers that the object had been destroyed when it passed close to the sun. Another satellite detected a small, bright object with a fan-shaped tail. What type of object were astronomers most likely observing?

• a comet
• an asteroid
• a meteor
• a nebula

Which list places four components of the universe in the most likely order from smallest to largest?

• planet, star, galaxy, nebula
• nebula, star, planet, galaxy
• galaxy, star, planet, nebula
• planet, star, nebula, galaxy

Which of these correctly compares the masses of different objects in the universe?

• a moon has less mass than a star and more mass than the planet it orbits
• a planet has less mass than a galaxy and more mass than the star it orbits
• a galaxy has less mass than a moon and more mass than a planet
• a star has less mass than a galaxy and more mass than a planet

Four students are asked to describe a nebula and a star. Their responses are shown in the table below. Which student described these two celestial bodies correctly ?

• Student 1
• Student 2
• Student 3
• Student 4