Introduction to Astronomy Test 1

This Study Set covers all information

astronomy

The branch of science that deals with celestial objects, space, and the physical universe as a whole.

Geocentric

A model of the universe in which Earth is at the center of the revolving planets and stars.

Heliocentric

the belief that the sun is the center of the a Solar System

Aristarchus of Samos (310-230 BC)

Created the first Heliocentric model of the Solar System

Eratosthenes of Cyrene

calculated the circumference of the earth with astounding accuracy

Claudius Ptolemy (85 - 165 CE)

By using Ptolemy's tables, astronomers could accurately predict eclipses and the positions of planets.

Nicolaus Copernicus (1473 - 1543 CE)

Produced a mathematical model of the Universe in which the Earth and other planets rotated around the Sun.

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Argued that Earth takes one year to orbit the sun and wobbles gradually on its axis.

Johannes Kepler (1571 - 1630 CE)

Created Kepler's 3 Laws of Planetary motion

What are Kepler's 3 Laws of Planetary Motion

(1) every planet's orbit is an ellipse with the Sun at a focus;

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(2) a line joining the Sun and a planet sweeps out equal areas in equal times

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(3) the square of a planet's orbital period is proportional to the cube of the semi-major axis of its orbit ( the further from the sun a planet is the longer its orbit will take)

Edwin Hubble (1889-1953) C.E.

Created the classifications of galaxies as well as the Idea of Redshift

spiral galaxy

a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern

Spiral barred galaxy

spiral galaxy in which a bar of material passes through the center of the galaxy, with the spiral arms beginning near the ends of the bar

Elliptical Galaxy

A galaxy shaped like a round or flattened ball, generally containing only old stars

Irregular Galaxy

A galaxy that has an undefined shape; irregular galaxies have large numbers of young stars and greats amounts of gas and dust are usually found near larger galaxies.

What is redshift and blueshift?

blueshift- a galaxy that is moving toward us will have shorter light wavelengths, and spectral lines appear bluer

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redshift- a galaxy that is moving away from us will appear to have longer light wavelengths, and spectral lines appear redder

Galileo Galilei (1564-1642 CE)

first to use a refracting telescope to make important astronomical discoveries. Very well known for modifying types telescopes.

Albert Einstein (1879-1955 CE)

Theory of special relativity that expresses the fact that mass and energy are the same physical entity and can be changed into each other. E= mc2

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Photon theory of light- Light acts like particle/ wave

Photon theory of light

* Light acts like particle/ wave

Hubble's Law

the speed of an object in space, depend on the distance between it and another body.

Cosmology

study of the Universe's Origin, Life, and end

Big Bang Theory

The theory that the universe originated in a huge explosion that released all matter and energy. This theory also states everything in the universe is expanding away/ outward.

Stellar Evolution

the changes in size, luminosity, temperature, and chemical composition that occur as a star ages, over its life cycle. ( its life cycle is based on the stars mass

The life cycle of a LOW mass star

Step 1: Large cloud of gas (Nebula)

Step 2: Forms protosun.

Step 3: Nuclear fusion causes light and energy to be released.

Step 4: Enters Main Sequence

Step 5: Forms into a Red Giant

Step 6: SuperNova

Step 7: White Dwarf

The life cycle of a HIGH mass star

Step 1: Large cloud of gas (Nebula)

Step 2: Forms protosun.

Step 3: Nuclear fusion causes light and energy to be released.

Step 4: Stars enter its Main Sequence.

Step 5: Forms into a SUPER Red Giant

Step 6: Produces a Supernova

Step 7: if mass is too low it will become a Neutron Star, if mass is too high the star will collapse into a black hole

What is the HR diagram?

a graphical tool that astronomers use to classify stars according to their luminosity and, temperature used to determine a stars evolutionary stage, spectral type, and color

What is a main sequence star?

any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward.

What is a red giant?

a star burning hydrogen into helium in a shell around the core, a large star of high luminosity and low surface temperature

What is a red super giant?

A star that has used up all the hydrogen and is now using helium as a fuel. It creates heavy elements and has a mass much greater than the Sun. Extremely high luminosity with a very low temperature

What is a white dwarf?

A small, hot, dim star that is the leftover center of an old star

What is a blue giant star?

a bluish star that has a high surface temperature, a large diameter, and a HIGH luminosity

Luminosity

brightness of a star compared to the sun

What will the outcome of our universe be if it is a open Universe

Expansion of the universe will NEVER STOP!! If our Universe's density isn't enough for Gravity to stop it from Expanding forever. This will result in the Big Rip!

What will the outcome of our universe be if it is a Closed Universe

Expansion will slow down and eventually stop its Expansion and eventually will begin Contraction where it will then collapse inwards back into the original point of the Universe's Origin. Resulting in the "Big Crunch"

What will the outcome of our universe be if it is a Flat Universe

Expansion will continue however it will slow, as objects slow for an infinite amount of time, all stars will explode leaving the Universe to eventually be left cold, dark, and frozen, this outcome is known as the Big Freeze.

What is the electromagnetic spectrum?

the complete range of electromagnetic waves placed in order of increasing frequency

What is wavelength?

the distance between corresponding points on adjacent waves, the distance between two crests of a wave.

What is frequency?

the number of waves that pass a given point over a period of time

What is amplitude?

distance between the resting position and the maximum displacement of the wave (The height of a wave)

what is the correlation between wavelength and frequency?

as Wavelength decreases the frequency of a wave goes up. and as Frequency goes down wavelength increases. This is an inverse relationship.

What is the visible light spectrum?

400-700 nm, ROYGBIV. The very small section of the electromagnetic spectrum that the human eye can perceive

What are radio waves?

Electromagnetic waves with the longest wavelengths and lowest frequencies, we can use Radio telescopes to see planets and galaxies that cannot be seen with the human eye

What do we use Microwaves for within the Universe

CMB or Cosmic Microwave Background radiation. we use this as evidence for the big bang and this background radiation is like the shock wave of the big bang

Infrared Radiation

Infrared radiation is mostly derived from massive amounts of heat. we use this radiation to locate large amounts of heat within our universe.

Ultra Violet Radiation

one of the closest to visible light and is on the blue end of the spectrum. Temperature, distance, and composition of objects and places in space can all be determined.

X-rays

This specific radiation is helpful for locating stars which are releasing large amounts of energy.

Gamma Rays

Electromagnetic waves with the shortest wavelengths and highest frequencies, used to measure EXTREMELY HIGH amounts of energy

What is the order of the Electromagnetic Spectrum from Longest to Shortest

radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and finally gamma rays

what is a spectroscope

device that contains a prism and displays the total visible spectrum if there is a source which emits white light. if the object does not emit white light you will instead see a different spectrum of light.

Bright Line Spectrum

The lines of visible light emitted by elements. every element creates a DIFFERENT bright line spectrum.

Dark Line Spectrum

as light in space passes through a gas depending on the element the gas is, it will absorb specific wavelengths of light creating dark lines on the visible spectrum.

Other Galaxies within the Universe were initially thought to be\_________.

Nebulas or star clusters

Elliptical galaxies are divided into sub classes based on \________.

the ratio from a sphere to a stretched disk.

Observations of our Universe show that its expansion is \__________.

Speeding up

A spiral Galaxy is classified as

"S"

A barred spiral Galaxy is classified as

"SB"

A galaxy that has a flat disk with no Spiral Arms

"SO"

A Spherical Elliptical Galaxy

"E0"

How would you classify an Irregular Galaxy

"Irr"

(True or False) Most Galaxies within our Universe are evenly spread throughout the Universe

False

The Milky Way and Andromeda are both examples of \___________.

Galaxies

(True or False) The sun is located in one the Milky way ways arms roughly 26,000 light years from the center of the galaxy

True

Galaxies are classified based on their

shape

What is the age of the universe?

13.7 billion years old

As the universe expanded and cooled, the radiation would have been shifted to \___________ energies and longer wavelengths.

Lowed energies

Where does most star formation occur within the Milky Way

It's arms

Astronomers look at the Fact that our Universe is expanding in order to theorize that it must have a \____________.

beginning

Evidence suggests that the Universe contains a great amount of \____________.

Dark Matter