Chapter 3 - Stars, Galaxies, and the Universe Flashcards
What is a light-year?
Is the distance that light travels in one year, about 9.46 trillion kilometers.
(Is a unit of distance, not time)
What is scientific notation?
Uses powers of 10 to write very large or very small numbers and shorter form.
(i.e. 1,200 ➡️ 1.2 x 10 to the third power)
What are binary stars?
Star systems I have two stars. (Also known as double stars)
What is parallax?
Is the apparent change in position of an object when you look at it from different places.
(Also how astronomers measure distances to nearby stars)
What is mass?
Is the amount of matter in an object.
What is weight?
The measure of the force of gravity on an object.
What is inertia?
The tendency of an object to resist a change in motion.
What is Newton’s first law of motion?
Says that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by force.
What is accretion?
Process of building something up gradually by the gathering together of
smaller pieces.
How are stars classified?
Characteristics used to classify stars include color, temperature, size, composition, and brightness.
What is the chemical composition of most stars?
About 73% hydrogen, 25% helium, and 2% other elements by mass.
What is a spectrograph?
It’s a device that breaks light into colors and produces an image of the resulting spectrum.
What is apparent brightness?
Is its brightness as seen from Earth. (Also known as apparent magnitude)
What is absolute brightness?
Is the brightness the star would have if it were at a standard distance from earth. (Also known luminosity)
How is a star born?
A star is born in the contracting gas and dust from the nebula become so dense and hot that nuclear fusion starts. How long a star lives depends on its mass.
