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universe

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is the totality of all space, time, matter, and energy

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astronomy

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is the study of the universe

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light-years

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distance that light, moving at constant speed of 300,000 km/s travels in one year

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theory

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framework of ideas and assumptions used to explain observations and make predictions- must be continually tested

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theoretical model

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is a theory designed to explain an entire situation or behavior, eventually able to predict that behavior

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scientific method

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based on the idea that scientific "laws" be continually tested, and modified, or replaced if found inadquate

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constellations

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a human grouping of stars in the night sky into a recognizable pattern

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celestial sphere

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imaginary sphere surrounding Earth to which all objects in the sky were once considered to be attached

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rotation

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the action of turning on an axis

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celestial poles

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projection of earth's north or south pole onto the celestial sphere

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celestial equator

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projection of earth's equator on the celestial sphere

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ecliptic

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is plane of earth's path around the sun at 23.5 degrees to the celestial year

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revolution

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orbital motion of one body about another

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zodiac

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the 12 constellations on the celestial sphere through which the sun appears to pass during the course of a year

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summer soltice

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point on the ecliptic where the sun is at the northernmost point above the celestial equator occurring on or near June 21

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winter soltice

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point on the ecliptic where the sun is at the southernmost point below the celestial equator occurring on or near December 21

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sesaons

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changes in average temperature and length of the day that result from the tilt of the earth's(or any planet) axis with respect to the planet of its orbit

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precession

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the slow change in the direction of the rotation axis of a spinning object caused by some external gravitational influence

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sidreral year

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the time required for the constellations to complete one cycle around the sky and return to their starting points as seen from a given point on earth, earth's orbital period is one of theses year

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phases

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appearance of the sunlit face of the moon at different points along its orbit, as seen from earth

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sidreral month

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time required for the moon to complete one trip around the celestial sphere

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eclipse

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event during which one body passes in front of another so that light from the occulted body is blocked

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lunar eclipse

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celestial event during which the moon passes through the shadow of earth, temporarily darkening its surface

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partial lunar eclipse

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celestial event during which only part of the occulted body is blocked from view

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total lunar eclipse

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celstial event during which one body is completely blocked from view by another

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solar eclipse

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celestial event during which the new moon passes directly b/w the sun and earth temporarily blocking the sun's light

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retrograde motion

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backward, westward loop traced out by a planet with respect to the fixed stars

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astronomical unit (AU)

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the average distance of earth from the sun

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period

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the time needed for planet to compete one circuit around the sun

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polaris

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north star

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how many constellation?

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88

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how far is the sun?

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93 million miles away

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inferior planets-orbit closer to sun

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mercury, venus

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superior planets-orbit further from sun

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Mars, Jupiter, Saturn

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conjuction

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a lined with the earth and the sun(planet)

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electromagnetic radiation

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another term for light, transfers energy and information from one place to another

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gamma ray

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far beyond the visible spectrum, corresponding to radiation of very high frequency and very short wavelength

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amplitude

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height of depth of a wave above or below the zero point

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wave motion

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transmit energy w/o the physical transport of material

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frequency

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number of waves crest that pass a given point per second

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wavelength

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distance b/w successive crests

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infrared

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having a wavelength just greater than that of the red end of the visible light spectrum but less than that of microwaves

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ultrviloet

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having a wavelength shorter than that of the violet end of the visible spectrum but longer than that of X-rays

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x rays

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corresponding to radiation of high frequency and short wavelength, far beyond visible spectrum

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velocity

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speed at which crests move

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relationship b/w velocity and wavelength

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velocity=wavelength/period

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electromagnetic waves

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oscillating electric and magnetic fields

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what is the wave speed of electromagnetic wave?

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c=3.0 x10^8

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blackbody spectrum

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radiation emitted by an object depending only on its temperature

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absorption spectrum

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if a continuous spectrum passes through a cool gas, atoms of the gas will absorb the same frequencies they emit created when atoms absorb photons of right energy for excitation

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Kirchhoff's law

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-luminous solid , liquid, or dense gas produces continuous spectrum -low density hot gas produces emission spectrum -continuous spectrum incident on cool, thin gas produces absorption

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emission energies

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correspond to energy differences b/w allowed levels

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photoelectric effect

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-when light shines on metal, electrons can be emitted -frequency must be higher than minimum characteristic of material -increased frequency more energetic electrons -increased intensity more electrons same energy

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Energy equation

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E=hf h=6.63 x 10^-34 joule seconds

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multielectron atoms

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much more complicated spectra, many more possible states

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ionization

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changes energy levels

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electron transitions

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produce visible and ultraviolet lines

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vibrational transitions

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produce infrared lines

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rotational transitions

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produce radio-wave lines

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infrared radiation

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can image where visible radiation; generally can use optical telescope mirrors and lenses

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interferometry

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involves combining signals from two receivers; the amount of interference depends on the direction of the signal

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How many stars are visible at night?

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3000 stars at any one time

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declination

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latitude

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right ascension

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longitutde

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Why aren't stars aren't in quite the same place 24 hours later?

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due to Earth's rotation around Sun;

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sidereal day

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day measured by stars

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Newton's laws

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1. inertia 2. f= ma 3. equal and opposite reaction

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Wein's Law

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wavelength of peak emission is inversely proportional with temperature

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Stephen's law

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total energy radiated per second is proportional with temperature

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Kirchoff's Laws

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Laws on spectroscopy (continuous, emission, absorption)

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Ground State

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the normal condition of the electron as it orbits the nucleus

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What Do Light Waves have in common? How do they differ?

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They are all electromagnetic radiation. They have different wavelength, frequency, and energy

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In terms of its blackbody curve, describe what happens as a red hot glowing coal cools

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As an object cools, then its peak will move to the left, ie lower frequency/longer wavelength (Wien's Law). The total area underneath will also decrease (Stefan's Law).

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Explain how astronomers might use spectroscopy to determine the composition and temperature of a star

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When light from a star is passed through a prism or similar device, a spectrum is produced. Spectroscopy is the observation and study of these spectra. For example, by studying the patterns of dark absorption lines in the spectrum of a star, a variety of information can be determined, including composition and temperature

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How do astronomers use the Doppler effect to determine the velocities of astronomical objects?

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Our perception of the wavelength of a beam of light can be altered by the source's velocity relative to us. Any net motion of the source away from the observer causes a redshift and any motion toward the observer causes a blue shift

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What is the cause of sunspots, flares and prominences

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magnetic fields

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Why do we see stars at different times of the year?

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This is because, at different times of the year, the earth faces different stars due to being positioned on a different side of the sun.

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Briefly describe Kepler's three laws of planetary motion.

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1) planets orbits are ellipses with the Sun at a focus 2) Planet moves faster when closer to the sun 3) The period squared equals the semimajor axis cubed

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What does it mean to say that kepler's laws are empirical?

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"Empirical" claims something as based on observations

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What is diffraction, and how does it relate to wave motion?

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Diffraction is the bending of EM waves around an object. Caused by the shape of a wave

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What do radio waves, infared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays have in common? How do they differ?

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All of these are EM waves. They just all have different wavelengths/frequencies

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In what parts of the electromagnetic spectrum is the atmosphere transparent enough for ground-based astronomy?

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visible light, some infared light, and some radio waves

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What are the 6 main regions of the electromagnetic spectrum from longest to shortest wavelength. For electromagnetic waves we can detect with our eyes, what color do we observe from longer wavelengths? shorter wavelengths?

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Radio Infared Visible (red is longer, blue is shorter) ultraviolet X-rays Gamma rays

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What is an absorption spectrum? An emission spectrum? How are they related?

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Emission spectrum=pattern of light Emitted by a gas absorption spectrum=same as above but absorbed the colors are the same wavelengths for the same gas

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What is spectroscopy? How can spectroscopy be used to infer the composition and temperature of a star?

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Spectroscopy is the study of spectral lines emitted by different substances, meaning that if one could see the spectral emission from a star, its composition and temperature could be determined

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Why do excited atoms absorb and reemit radiation at characteristic frequencies?

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because the electrons absorb the energy and jump up a level or let out energy and go down one. They do this at a specific frequency because each different energy level takes a different frequency to move since there is a different in the atom's composition.

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List three properties of a star that can be determined from observations of its spectrum

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temperature, state, composition

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List three advantages of reflecting telescopes over lenses.

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better for spherical aberration -better for chromatic aberration, -has a better support structure

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Cite two reasons that astronomers are continually building larger and larger telescopes.

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Bigger telescope, more light gathered, the better the image. AND it increases the resolving power

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What are the main advantages of studying objects at many different wavelengths of radiation?

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Different wavelengths in observation reveal different things about the universe, helping astronomers to get the full picture

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list and describe the three powers of a telescope. Which of these is most important?

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Light gathering power (most important) is the ability of the telescope to gather light. Resolving power is the telescope's ability to distinguish fine detail. Magnification power is the enlargement of an image.

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Reflecting telescopes:

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Most commonly used by professional astronomers today -Hubble space telescope -World's largest telescope

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Refracting telescopes:

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-The world's largest is 10 meters in diameter -Galileos telescopes -Very large telescopes become "top-heavy" -Incoming light passes through glass

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accreation

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gradual growth of bodies, such as planets, by the accumulation of other smaller

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angular diameter

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angle made b/w the top (or one edge) of an object, the observer, and the bottom(or opposite) of the object

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asteroid

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1 of thousands of very small members of the solar system orbiting the sun b/e the orbits of mars and Jupiter

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asteroid belt

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region of the solar system, b/w the orbits of mars and Jupiter in which most asteroids are found

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comet

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a small body, composed mainly of ice and dust in an elliptical orbit about the sun. As it comes close to the sun, some of its material is vaporized to form a gaseous head and extended head and tail.

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core-accretion theory

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theory that the Jovian planets are formed when icy pro planetary cores became massive enough to capture gas directly from the solar nebula

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density

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a measure of the compactness of the mater w/in an object, compute by dividing the mass of the object by its volume. Units are kilograms per cubic meter or grams per cubic centimeter

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gravitational instability theory

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theory that the jovian planets forme directly from the solar system nebula via instabilities in the gas leading to gravitational contraction

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jovian planet

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one of the four giant outer planets of the solar system resembling Jupiter in physical an chemical composition

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kuiper belt

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a region in the plane of the solar system outside the orbit of Neptune where most short-period comets are thought to originate

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mass

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a measure of the total amount of matter contained w/in an object

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meteroid

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chunk of interplanetary debris prior to encountering Earth's atomosphere

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moon

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a small body in orbit around a planet

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oort cloud

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spherical halo of material surrounding the solar system out to a distance about 50,000 AU; where most comets reside

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orbital inclination

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is the angle between a reference plane and the orbital plane or axis of direction of an object in orbit around another object.

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orbital period

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time taken for a body to complete one full orbit around another

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planet

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one of eight major bodies that orbit the sun, visible to us by reflected sunlight

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planetesimal

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term given to objects in the early solar system that had reached the size of small moons, at which point their gravitational fields were strong enough to begin influencing their neighbors

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protoplanet

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clump of material, formed in the early stages of solar system formation, that was the forerunner of the planets we see today

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protostellar disk

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swirling disk of gas and dust w/in which star forms. The "solar nebula," in the case of our sun

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protosun

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the central accumulation of material in the early stages of solar system formations, the forerunner of the present-day sun

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radius

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a circle or sphere is a the length of a line segment from its center to its perimeter

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rotation period

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a celestial object is the time that it takes to complete one revolution around its axis of rotation relative to the background stars.

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semi-major axis

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one-half of the major axis of an ellipse, is the way in which the size of an ellipse is usually quantified

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solar nebula

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the swirling gas surrounding the early sun during the epoch of solar system formation

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solar system

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the sun and all the bodies that orbit it-mercury, Venus, earth, Jupiter, Saturn, Uranus, Neptune, their moons, the asteroids, the comets, and trans-Neptunian objects

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terrestrial planet

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one of the four innermost planets of the solar system, resembling earth in general physical and chemical properties

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volume

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the amount of space that a substance or object occupies, or that is enclosed within a container, especially when great.

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