PHYS 284 Midterm UPDATED Actual
Exam Questions and CORRECT Answers
star - CORRECT ANSWER✔✔- A large, glowing ball of gas that generates heat and light
through nuclear fusion in its core. Our Sun is a star.
planet - CORRECT ANSWER✔✔- A moderately large object that orbits a star and shines
primarily by reflecting light from its star. According to the current definition, an object can be
considered a planet only if it (1) orbits a star, (2) is large enough for its own gravity to make
it round, and (3) has cleared most other objects from its orbital path. An object that meets the
first two criteria but has not cleared its orbital path, like Pluto, is designated a dwarf planet.
moon - CORRECT ANSWER✔✔- An object that orbits a planet. The term satellite is also
used more generally to refer to any object orbiting another object.
asteroid - CORRECT ANSWER✔✔- A relatively small and rocky object that orbits a star.
comet - CORRECT ANSWER✔✔- A relatively small and ice-rich object that orbits a star.
small solar system body - CORRECT ANSWER✔✔- An asteroid, comet, or other object that
orbits a star but is too small to qualify as a planet or dwarf planet.
solar system - CORRECT ANSWER✔✔- The Sun and all the material that orbits it,
including planets, dwarf planets, and small solar system bodies. Although the term solar
system technically refers only to our own star system (solar means "of the Sun"), it is often
applied to other star systems as well.
star system - CORRECT ANSWER✔✔- A star (sometimes more than one star) and any
planets and other materials that orbit it.
galaxy - CORRECT ANSWER✔✔- A great island of stars in space, all held together by
gravity and orbiting a common center, with a total mass equivalent to millions, billions, or
even trillions of stars.
, galaxy cluster - CORRECT ANSWER✔✔- A collection of galaxies bound together by
gravity. Small collections (up to a few dozen galaxies) are generally called groups, while
larger collections are called clusters.
super cluster - CORRECT ANSWER✔✔- A gigantic region of space in which many groups
and clusters of galaxies are packed more closely together than elsewhere in the universe.
universe - CORRECT ANSWER✔✔- The sum total of all matter and energy—that is, all
galaxies and everything between them.
observable universe - CORRECT ANSWER✔✔- The portion of the entire universe that can
be seen from Earth, at least in principle. The observable universe is probably only a tiny
portion of the entire universe.
astronomical unit - CORRECT ANSWER✔✔- The average distance between Earth and the
Sun, which is about 150 million kilometers. More technically, 1 AU is the length of the
semimajor axis of Earth's orbit.
light year - CORRECT ANSWER✔✔- The distance that light can travel in 1 year, which is
about 10 trillion kilometers (more precisely, 9.46 trillion km).
rotation - CORRECT ANSWER✔✔- The spinning of an object around its axis. For example,
Earth rotates once each day around its axis, which is an imaginary line connecting the North
and South Poles.
orbit - CORRECT ANSWER✔✔- The orbital motion of one object around another due to
gravity. For example, Earth orbits the Sun once each year.
expansion - CORRECT ANSWER✔✔- The increase in the average distance between
galaxies as time progresses.
constellation - CORRECT ANSWER✔✔- a region of the sky with well-defined borders; the
familiar patterns of stars merely help us locate the constellations.
Exam Questions and CORRECT Answers
star - CORRECT ANSWER✔✔- A large, glowing ball of gas that generates heat and light
through nuclear fusion in its core. Our Sun is a star.
planet - CORRECT ANSWER✔✔- A moderately large object that orbits a star and shines
primarily by reflecting light from its star. According to the current definition, an object can be
considered a planet only if it (1) orbits a star, (2) is large enough for its own gravity to make
it round, and (3) has cleared most other objects from its orbital path. An object that meets the
first two criteria but has not cleared its orbital path, like Pluto, is designated a dwarf planet.
moon - CORRECT ANSWER✔✔- An object that orbits a planet. The term satellite is also
used more generally to refer to any object orbiting another object.
asteroid - CORRECT ANSWER✔✔- A relatively small and rocky object that orbits a star.
comet - CORRECT ANSWER✔✔- A relatively small and ice-rich object that orbits a star.
small solar system body - CORRECT ANSWER✔✔- An asteroid, comet, or other object that
orbits a star but is too small to qualify as a planet or dwarf planet.
solar system - CORRECT ANSWER✔✔- The Sun and all the material that orbits it,
including planets, dwarf planets, and small solar system bodies. Although the term solar
system technically refers only to our own star system (solar means "of the Sun"), it is often
applied to other star systems as well.
star system - CORRECT ANSWER✔✔- A star (sometimes more than one star) and any
planets and other materials that orbit it.
galaxy - CORRECT ANSWER✔✔- A great island of stars in space, all held together by
gravity and orbiting a common center, with a total mass equivalent to millions, billions, or
even trillions of stars.
, galaxy cluster - CORRECT ANSWER✔✔- A collection of galaxies bound together by
gravity. Small collections (up to a few dozen galaxies) are generally called groups, while
larger collections are called clusters.
super cluster - CORRECT ANSWER✔✔- A gigantic region of space in which many groups
and clusters of galaxies are packed more closely together than elsewhere in the universe.
universe - CORRECT ANSWER✔✔- The sum total of all matter and energy—that is, all
galaxies and everything between them.
observable universe - CORRECT ANSWER✔✔- The portion of the entire universe that can
be seen from Earth, at least in principle. The observable universe is probably only a tiny
portion of the entire universe.
astronomical unit - CORRECT ANSWER✔✔- The average distance between Earth and the
Sun, which is about 150 million kilometers. More technically, 1 AU is the length of the
semimajor axis of Earth's orbit.
light year - CORRECT ANSWER✔✔- The distance that light can travel in 1 year, which is
about 10 trillion kilometers (more precisely, 9.46 trillion km).
rotation - CORRECT ANSWER✔✔- The spinning of an object around its axis. For example,
Earth rotates once each day around its axis, which is an imaginary line connecting the North
and South Poles.
orbit - CORRECT ANSWER✔✔- The orbital motion of one object around another due to
gravity. For example, Earth orbits the Sun once each year.
expansion - CORRECT ANSWER✔✔- The increase in the average distance between
galaxies as time progresses.
constellation - CORRECT ANSWER✔✔- a region of the sky with well-defined borders; the
familiar patterns of stars merely help us locate the constellations.
