chapter 18 Review Flashcards
The ________ is the totality of all matter, energy, and space.
Universe
the huge imaginary sphere of the sky on which all the stars seem to be located is the __________
celestial sphere
A ________ is the distance (3.26 ly) to an object with a parallax of 1 arc second.
parsec
The layer of the sun that we see is the ________
photosphere
_____________ is a measure of the brightness of a star as seen from earth.
Apparent magnitude
________ is a measure of the brightness of a star if I we seen from a standard distance of 10 pc (32.6 ly).
The band of stars from the upper left to the lower right in above plot that most stars fall into is the ____________.
main sequence
The relatively cool bright stars with diameters 10-100 times that of the sun are the __________
red giants
________ are cool denser clouds of interstellar gas and dust
nebula
The shell of gas ejected from an old low mass stairs a __________
planetary nebula
A white dwarf star that suddenly increases dramatically in brightness for a brief period of time is a ____________
nova
when a star explodes it is a ___________
super nova
All elements heavier than _______ are made in _______ explosions.
iron, supernova
A _______ is The extremely dense remnant of a high mass star that is made of neutrons
neutron star
A rapidly rotating that appears to pulse on and off is called a __________
pulstar
A large gravitationally bound collection of stars and gas is a _________
galaxy
Galaxies come in 3 types
elliptical
spiral
irregular
The additional mass required the keep galaxies gravitationally bound that we cannot see is called ________.
black matter
The study of the structure and history of the the entire universe is
cosmology
Hubble’s law say the further away a galaxy is the _________ it is travelling away from us
faster
The force accelerating the expansion of the universe is called
energy
The universe is expanding because the __________ itself is expanding.
space
The _______Theory of the beginning of the universe states that the known universe was smaller, hotter, and denser in the past, and that it began rapidly expanding 13.8 billion years ago.
Big Bang
What is the point on the celestial sphere representing the extension of the axis of Earth’s North Pole?
North celestial pole
What is the name of the path on the sky that the Sun appears to follow as it moves among the stars?
the ecliptic
Define the term cosmology.
The branch of astronomy that is the study of the structure and evolution of the universe.
Which is the larger unit of distance, the light-year or the parsec?
the parsec
Why are sunspots darker than the regions of the Sun around them?
They are cooler than the surrounding material.
Where in the Sun does fusion of hydrogen occur?
only in the core
What is the approximate temperature (in K) of the Sun at its surface?
6,000 K
A relatively cool star is what color?
red
Which star is closest to the Sun?
Proxima Centauri
A white dwarf has about the same diameter as which of the following?
the Earth
Texas
the Sun
Jupiter
the Earth
How big will the Sun become as a red giant star?
It will engulf the orbits of Mercury, Venus and possibly the Earth.
Define the term nucleosynthesis.
the creation of nuclei inside stars
Describe how the mass of a star plays a role in the lifetime of a star.
The more massive the star, the shorter the lifetime.
What is the fundamental quantity of a star that indicates its ultimate fate?
Mass
What event is believed to create elements heavier than iron?
a supernova explosion
What is dark matter?
unknown exotic matter
How much of the universe appears to be normal ordinary matter?
5%
What is the cosmic background radiation?
the light-energy remnants of the explosion in which the universe was born
What key observation led Hubble to conclude that the universe is expanding?
the redshift of light from distant galaxies
What is the galaxy classification of the Milky Way galaxy?
barred spiral galaxy
What is a quasar?
The core of a young very active galaxy observed when the universe was very young.
The Milky Way is classified as what kind of galaxy?
spiral
Black holes appear black for what basic reason?
Light cannot escape them.
