Astronomy Mid-term – Flashcards

A scientific model must make an testable prediction.

Scientific theories can never be proved true beyond all doubt.

The observable universe is the same size today as it was a few billion years ago.

The solar system contains about 100 billion stars.

Stars with high masses live longer than stars with lower masses.

Kepler deduced his laws of planetary motion once Newton had published his universal law of gravitation.

There is no gravity in space.

Doubling the distance between two objects halves the gravitational force between them.

The escape velocity from Earth is greater for larger rockets than for small ones.

Unbound orbits have more orbital energy than bound orbits.

What is the average temperature of the surface of the Sun?

Roughly how many stars are in the Milky Way Galaxy?

How long does it take our solar system to complete one orbit around the Milky Way Galaxy?

Compared to the star it evolved from, a red giant is...

Which of the following statements about X rays and radio waves is not true?

How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?

Why is the spectral sequence of stars not alphabetical?

On a Hertzsprung-Russell diagram, where would we find red giant stars?

The set of spectral lines that we see in a star's spectrum depends on the star's:

Compared to the Sun, a star whose spectrum peaks in the infrared is:

that portion of the universe that we can see in principle, given the current age of the universe

the plane of Earth's orbit around the sun

the average distance between the earth and the sun

What does our solar system consist of?

typically has a collection of a few hundred million to trillion or more stars, bound together by gravity

the sum total of all matter and energy

the event that marked the beginning of the expansion of the universe

the age of the universe

approximately the number of stars in the galaxy

how long does it take for the earth to make one complete rotation around the sun?

an earth centered model of planetary motion published by Ptolemy

created detailed model of our solar system with the sun in the center rather than the earth

observed planetary positions with sufficient accuracy that Kepler could later use the data to discover laws of planetary motion

sealed the case for the sun centered solar system

observations using just a few general principles and has been verified by repeated and varied testing

is the rate at which an object is moving

speed in a certain direction

a change in velocity, meaning a change in either speed or direction

mass times velocity

can change an object's momentum causing it to accelerate

means that an objects momentum cannot change unless it transfers momentum to or from other objects. When no force is present, no momentum can be transferred so an object must maintain its speed and direction.

means that a planet's rotation and orbit cannot change unless it transfers angular momentum to another object.

the energy of a body or a system with respect to the motion of the body or the particles in the system

energy carried by light

the energy of a body or system with respect to the position of the body or the arrangement of the particles of the system

rate of energy transferred and measured in watts

an electromagnetic wave

light in individual pieces

in order of decreasing wavelengths, but increasing frequency and energy ex. radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays

type of electromagnetic radiation with the longest wavelengths, form of light

a particular element that all have the same number of protons but different number of neutrons

this process breaks up molecules and ionization strips electrons from atoms, an ionized gas is called a plasma

looks like rainbow of light

when specific colors are missing from the rainbow

when we see light only with specific colors against a black background

this tell us how fast an object is moving towards or away from us, spectral lines are shifted to shorter wavelengths (BLUESHIFT) in objects moving toward us and in longer wavelengths (REDSHIFT) in objects moving away from us.

this is why the sun shines, it keeps its core hot and dense enough to release energy through nuclear fusion.

plots stars according to their surface temperature and luminosities, giants and super giants are to the upper right or in the main sequence while the white dwarfs are to the lower left

are stars that have exhausted their core supplies of hydrogen for fusion and are undergoing other forms of fusion at a more rapid rate as they near the ends of their lives

stars that exposed cores of stars that have already died, meaning they have no further means of generating energy through fusion

based on every day ideas of observation and trial-error experiments

this cycle is used to keep lunar calendars approximately synchronized with solar calendars

How long does it take light to travel from the Moon to Earth

How long does it take light to travel from the Sun to Earth?

when we see sunspots on the surface of the sun

nuclear fusion of hydrogen into helium occurs here

this is where energy moves through this place in the sun by means of rising of hot gas and falling of cooler gas

nearly all the visible light is emitted from this narrow layer

most of the sun's ultraviolet light is emitted from this narrow layer, where temperature increases with altitude

this is the part of the sun that we can see most easily during a total solar eclipse

the layer of the Sun between its core and convection zone

the phase of matter in the sun is

first observed solar flare, an example of a dangerous sun-earth connection and responsible for unusually strong auroae

What happens to a low-mass star after a helium flash?

stars are classified on the basis of their spectral type and this

cepheids are an example of this

way a star can move, motion along the line of sight (towards or away from the observer)

motion that is perpendicular to the line of sight

a combination of the radial velocity and tangential velocity to give the true velocity of the star in space in km/s