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Astronomy 102 SECTION ONE
Terms in this set (87)
a large glowing ball of gas, that generates heat through nuclear fusion
a celestial body that orbits a star. It must move in an elliptical orbit around a star, be massive enough for its own gravity to make it round, and also big enough for it to have swept away smaller objects in its orbit.
a natural satellite of a planet; an object that revolves around a planet.
an often irregularly shaped rocky body that orbits a star.
a celestial object consisting of a nucleus of ice and dust
a cloud of gas and dust in space.
our Sun and the planets that move around it, or a star other than our sun and the planets that move around it.
a number of stars that orbit each other, bound by gravitational attraction.
a self-contained system of stars, stellar remnants, interstellar gas, dust, and dark matter.
Earth > solar system > Milky Way Galaxy > Local Group > Local Supercluster
What is the order of the universe?
a collection of galaxies bound together by gravity (usually a few hundred)
a gigantic region of space where many groups and clusters of galaxies are located (a few thousand)
all matter, energy, and space; everything that exists
the portion of the universe visible from Earth, the age of which is nearly 14 billion years, the diameter of which is estimated to be at least 91 billion light-years across.
Astronomical Unit (AU)
the average distance between Earth and the Sun (about 150 million km)
the distance light can travel in one year (9.4607 * 1012 km or nearly 6 trillion miles)
the path of a celestial body or arti cial satellite as it revolves around another body due to their mutual gravitational attraction (e.g. Earth orbits the sun anually)
the spinning of an object around its axis. (e.g. Earth rotates on its axis once a day)
The Milky Way Galaxy contains more than ____ stars
Over 100 billion
How many galaxies are there in the observable universe?
The limit to how far we can see in space-time
Roughly 14 billion years
How old is our universe?
25 million light years away
How far away is the Andromeda Galaxy?
230 million years
How long does it take the solar system to orbit the Milky Way Galaxy?
Edwin Hubble (1929)
Who found out that the further away a galaxy is, the faster it is moving away from us. (expanding universe)
Who showed that the Earth was not the centre of the universe and what year?
Track of seasons, keep time, calendar, monitoring the cycles of the Earth, moon, stars and other plants. produce solar and lunar eclipses
What was astronomy used for, for ancient societies?
Who accurately measured Earth's circumference in 240 B.C.
the study of planetary motion led to his laws in motion and gravity. His laws
laid the foundation for the industrial revolution
The Sun and planets revolve around the Earth
Geocentric model of the solar system
____ made the most sophisticated geocentric model back in 100-170 AD
How long was the geocentric model used for?
_____ is the Sun centred model
____ compiled the most accurate naked-eye measurements ever made of planetary positions
the effect whereby the positions of the stars appears to differ when viewed from different angles or points
1.) The orbit of each planet around the sun is an ellipse with the sun at one focus
2.) As a planet moves around its orbit, it sweeps out equal areas in equal times (this means that planets move faster closer to the sun and slower further from the sun)
3.) More distant planets orbit the sun at slower average speeds, obeying the relationship p2=a3
Kepler's three of Planetary motion
1.) First objection: Galileo showed objects on earth when thrown into the air would stay in the same motion as each unless acted on by another force (the previous theory was objects would leave earth if earth was moving fast through space. ex. if you threw a baseball into the air straight up it would disappear as earth is moving at incredible speeds)
2.) Second objection: Galileo used telescopes to view mountains and valleys on the moon and stated it WASNT a perfect sphere
3.) Third objection: Galileo observed stars being much further away then previously believed, stating earth would have room to move around in space. He also noted four moons orbiting Jupiter, proving not EVERY object in space orbits earth
How did Galileo solidified the Copernican revolution
1) An object at rest stays at rest, an object at motion stays in motional a constant velocity, unless acted upon by an unbalanced net force
2) force = mass
3) For every action (force) there is an equal and opposite reaction (force)
Newton's 3 laws of Motion
Copernicus created a sun-centred model; Tycho provide more data for this model; Kepler found a new model that fit Tycho's data
how did Copernicus, Tycho and Kepler challenge the earth-centred model?
a unit of energy
emitted, absorbed, reflected
Light can be....
is a kind of energy known as electromagnetic (EM). Can act as a particle or a wave
a pattern of motion that can carry energy without carrying matter along with it
the distance between two wave peaks
the number of times per second that a wave vibrates up and down
higher frequency = ____
____ is a vibration of electric and magnetic fields
Frequency * wavelength
short its wavelength
The higher the photon energy: the ___ its ____
White light is a mix of all the colours of the rainbow
Newtons experiments proved that...
Lowest energy, longest wavelength
lower energy, longer wavelength
low energy, long wavelength
high energy, shorter wavelength
higher energy, shorter wavelength
highest energy, shortest wavelength of all
A particle of matter indivisible by chemical means. It is the fundamental building block of elements.
The number assigned to each element on the basis of the number of protons found in element's nucleus.
Atomic weight (atomic mass)
Approximately the sum of the protons and neutrons found in the nucleus of an atom.
An opaque object that emits thermal radiation. A perfect blackbody absorbs all incoming light and does not re ect any. The higher the object's temperature, the higher the frequency of the radiation it emits.
Radiation consisting of electronic and magnetic waves that travel at the speeds of light. Examples: light, radio waves, gamma rays, x-rays.
A negatively charged subatomic particle.
The splitting of a heavy nucleus into two roughly equal, smaller nuclei.
A particle of light.
object moving towards us
object moving away from us
The Doppler Effect
An in the frequency of sound, light, or other waves toward (or away from) as the source and observer move
Continuous, emission, absorption
Three types of spectra
a lightbulb spans all visible spectrums without interruption
Emission line spectrum
a cloud of gas emits light only at specific waves so a spectrum showing vertical lines is used with breaks between
a cloud between us and a light bulb absorbs light leaving dark absorption lines in the spectrum (looks like dark vertical lines on top of a continuous spectrum
measure a planets temperature by studying its thermal radiation
You can use the colour spectrum chart to
Hotter objects emit more light and hotter objects emit photons with a higher energy
Properties of thermal radiation
When light moves _____ something it appears blue
when it moves ____ from an object it appears red
Each atom is a unique fingerprint. We can determine which atoms something is made of by looking for their fingerprints in the spectrum
How does light tell us what things are made of?
the bending of light when it passes from one substance to another. Your eyes use it to focus light
The _____ controls how much light enters the eye, by dilating in low light and constricting in bright light.
The _____ bends light to form an image on the retina
The _____ is where light from di erent directions comes into focus
Light collecting area and Angular resolution
The two most important properties of a telescope are:
Light collecting area
determines how much light a telescope can gather.
the minimum angular separation a telescope can
Refracting and reflecting
The two basic designs of telescopes are
focus light with lenses.
focus light with mirrors.
its light-collecting area
A telescope's diameter tells us....
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