Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
58 Cards in this Set
- Front
- Back
|
What is a light year?
|
A light year is the distance light travels in a year.
|
|
|
Mass will determine___ for a star.
|
lifetime
|
|
|
What color is the coolest star?
|
red
|
|
|
What is a parallax?
|
The apparent change of an object when you look at it from different places.
|
|
|
What is a parallax used for?
|
To measure distances of nearby stars from earth.
|
|
|
When is a star born?
|
A star is born when contracting gas and dust from a nebula become so dense that nuclear fusion occurs.
|
|
|
What color are the hottest stars?
|
blue
|
|
|
Name the characteristics used for classifying stars.
|
color,temperature,size,composition,brightness.
|
|
|
How many years may a star live?
|
10 million-500 billion years
|
|
|
A high mass star explodes and forms a?
|
supernova
|
|
|
What is a star system?
|
a group of two or more stars
|
|
|
What is a star cluster?
|
a large grouping of stars that formed from the same nebula at about the same time and are approximatley the same distance from Earth.
|
|
|
Name a difference between an elliptical galaxy and a spiral galaxy.
|
Elliptical looks like a flattened ball and a spiral looks like a pinwheel.
Stars no longer form in an elliptical galaxy but a lot form in a spiral galaxy. |
|
|
Name a spiral galaxy
|
the Milky Way
|
|
|
How did the solar system form?
|
Giant cloud of gas and dust collapsed.
|
|
|
The absolute brightness of a star depends on its____.
|
size and temp
|
|
|
What does the Hertzsprung-Russell diagram show?
|
star classification
|
|
|
Gravity is the force that pulls____ to form a star.
|
gas and dust/matter
|
|
|
What is an open cluster?
|
A star cluster that has a loose, disorganized appearance and contains about a few thousand stars.
|
|
|
What is a supernova?
|
An explosion of a dying supergiant.
|
|
|
What is the difference between an irregular galaxy and an elliptical galaxy?
|
Irregular galaxy has a lot of gas and dust that produce many stars and an elliptical galaxy has little to no gas/dust so stars are no longer forming. elliptical has defined shape but Irregular does not.
|
|
|
What is a spectograph used for?
|
to determine the stars chemical composition-the elements found in stars.
|
|
|
How can black holes form?
|
when a star that has a mass much greater than the sun collapse.
|
|
|
About 13.7 billion years ago___ formed.
|
universe
|
|
|
How does a supergiant form?
|
from a high-mass star when the core shrinks and the gas outerlayer expands
|
|
|
what is a white dwarf?
|
the blue-white core of a planetary nebula that is left behind after its outer layers expanded and drifted out into space.
|
|
|
how is apparent brightness different from absolute brightness?
|
apparent brightness is a stars brightness that it appears to be from earth and absolute brightness is the brightness a star would have if it were at a standard distance from earth.
|
|
|
imaginary patterns of stars are called_____
|
constellations
|
|
|
What reveals a stars surface temp?
|
color
|
|
|
stars that are mush larger than the sun are called___
|
giant/supergiant stars
|
|
|
true/false
Each element has a unique set of lines on a spectrum |
true
|
|
|
how can astronomers infer which elements are found in stars?
|
by comparing a stars spectrum with the spectrums of known elements.
|
|
|
what does a spectograph do?
|
a device that breaks light into colors and produces an image of the resulting spectrum.
|
|
|
what is the chemical composition of most stars?
|
73% hydrogen, 25% helium, 2% other elements.
|
|
|
The amount of light a star gives off is called its___
|
brightness.
|
|
|
What two factors determine how bright a star looks from earth?
|
absolute brightness and how far the star is from earth.
|
|
|
true/false
the closer a star is to Earth, the brighter it appears. |
true
|
|
|
what two things must an astronomer find out in order to calculate a stars absolute brightness?
|
apparent brightness and distance from earth
|
|
|
true/false
in space light travels at a speed of 300,000 kilometers per year |
false
|
|
|
a light year equals about____ kilometers.
|
9.5 million million
|
|
|
true/false
the light year is a unit of time. |
false
|
|
|
To measure parallax shift, astronomers look at the same star two different times of the year, when Earth is on different sides of the ____
|
sun
|
|
|
the diagram that shows the relationship between the surface temp of stars and their absolute brightness is called___
|
the Hertzsprung-Russell diagram
|
|
|
An area on the Hertzsprung-Russell diagram that runs from the upper left to the lower right and includes more than 90% of all stars is called the____.
|
main sequence.
|
|
|
the initial explosion that resulted in the formation and expansion of the universe is called the _____
|
big bang
|
|
|
when did the big bang occur
|
13.7 billion years ago
|
|
|
true/false
the farther away a galaxy is from us, the faster it is moving from us. |
true
|
|
|
How is the universe like rising raisin bread dough?
|
you can see all the raisins moving from you and the farther the raisins are from you, the faster they are moving away from you.
|
|
|
radiation left over from the big bang is called____
|
cosmic backround radiation
|
|
|
how can astronomers infer approximatley how long the universe has been expanding?
|
by measuring how fast galaxies move away from us and cosmic backround radiation.
|
|
|
about how long did our solar system form?
|
5 billion years ago
|
|
|
What events led to the birth of our sun?
|
a cloud of gas and dust formed a spinning disk then gas at the center of the disk collapsed.
|
|
|
How did planetismals form planets?
|
by colliding and growing bigger by sticking together
|
|
|
describe two possiblilities of what will happen to the universe in the future.
|
-the universe will expand so much and all the stars will die out and we will be in complete darkness
-gravity will pull all of the galaxies together and form the big crunch. |
|
|
In which direction are nearly all galaxies moving?
|
away from the milky way
|
|
|
what is hubbles law?
|
the farther a galaxy is from us, the faster it is moving from us.
|
|
|
dark matter
|
matter that does not give off electromagnet radiation
|
|
|
dark energy
|
a force that is causing the expansion of the universe to accelerate
|
