# class notes and Qs - Flashcards

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 Class: ASTR 152 - ELEM ASTRONOMY Subject: Astronomy University: California State University - Northridge Term: Fall 2014
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 Astronomical Unit The average distance between the Earth and the Sun is defined as being one Consider even the Earth and the Moon. About how many moons would fit across the Earth? 4 The Earth's diameter is about 13,000 km while the distance between the Earth and the Moon is about 390,000 km. How many Earth's would fit between the Earth and the Moon? 390000/13000= 30 times What types of distances are typically listed in astronomical units? distances in solar system
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 What is a star, 1 AU from earth, and 100x diameter of earth? The Sun List from Smallest to Largest: Milky Way, Solar System, Earth, Galaxies Earth, Solar System, Milky Way, Galaxies If the nearest star is 4.2 light-years away, then... the light we see left the star 4.2 years ago 3.9x105 is the same as 390,000
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 Light takes about 8 minutes to travel from the Sun to Earth. Light takes about 40 minutes to travel from the Sun to Jupiter. How many astronomical units is Jupiter from the Sun? 40 / 8 = 5 Light takes about 8 minutes to travel from the sun to Earth. Mars is approximately 1.5 AU from the Sun. How many light minutes is Mars from the Sun? 8 x 1.5 = 12 If you were located on the boundary between daylight and darkness on the right side of the earth in this picture, would you be experiencing sunrise or sunset? Why? Sunset. Because Earth rotates counterclockwise when viewed from above Earth's North Pole. A region of the sky containing a recognizable pattern of stars is called a Constellation
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 The apparent visual magnitudes of four stars are listed below. Of these four stars, which one appears dimmest in the sky? + 2.8 If the apparent visual magnitude of a star is 7.3. This tells us that the star is Not visible to the naked eye Objects A and B both have the same angular size, and Object A is closer to us than object B. Which of the following can we conclude? A < B Proxima Centauri, the nearest star outside of our solar system, is about _______ times farther away from the Sun than Pluto 7000
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 Universe the totality of all space, time, matter and energy. 10,000,000 is 10 raised to what? 6 Milky Way the galaxy we live in Sirius the brightest star in the night sky
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 Of the apparent visual magnitudes listed below, which corresponds to the faintest star in our sky that can still be seen with the naked eye? + 4.5 The Big Dipper is the name of an... Asterism What is the dividing the celestial sphere into northern and southern hemispheres celestial equator Constellations that do not set and are always above our horizon are called Circumpolar
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 Horizon The imaginary boundary between the earth and sky North celestial pole The point on the celestial sphere directly above the north pole of the earth South celestial pole the point on the celestial sphere directly above the south pole of the Earth zenith The point in the sky directly overhead of any observer
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 What is the celestial sphere? The celestial sphere is a representation of how the entire sky looks as seen from Earth Suppose an astrophotographer hands you a picture with star trails taken looking toward the north celestial pole. If the star trails are 1/6 of a complete circle, about how many hours was the picture exposed? 4 (24 hours * 1/6) ecliptic The apparent path of the Sun through the constellations as viewed from Earth autumnal equinox the sun is crossing the celestial equator moving south
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 vernal equinox the sun is crossing the celestial equator moving north winter solstice the sun is farthest south summer solstice the sun is farthest north The sun appears on the equator on equinoxes
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 precession The gradual wobble that changes the orientation of earth's axis Will there be a zenith in Los Angeles No. We are too far north. Which of the following best describes why we have seasons on Earth? The tilt affects sunlight The maximum tilt of the northern hemisphere toward the sun occurs on…. the first day of summer
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 What is the angle between the earth's equator and the plane of the earth's orbit around the sun? 23.5 Why is it summer in Los Angeles during June? the rays from the sun fall more directly on Los Angeles in June The changing position of the North Celestial Pole over a 26,000 year period is due to the Earth's precession Apogee The point on the moon's orbit farthest from Earth
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 perigee The point in the moon's orbit closest to the Earth Nodes The points where the moon's orbit crosses the ecliptic Penumbra The region of a shadow that is partially shaded Saros cycle is the roughly 18-year cycle over which the pattern of eclipses repeats.
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 At about what time will the moon rise during a last quarter phase? midnight What will the phase of the moon be 10 days after a first quarter moon? waning gibbous umbra The region of a shadow that is totally shaded Why we cannot see a new moon in our sky sometimes it is too close to the sun in our sky
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 The moon always shows nearly the same face toward earth because the Moon rotates once in the same amount of time that it takes the Moon to orbit Earth synodic period The time for the moon to repeat its cycle of phases is equal to its... Full moon always occurs when the moon is directly opposite to the position of the sun During which phase of the moon do lunar eclipses occur? full moon
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 By approximately how many degrees does the moon's position change from one day to the next? 13 During which phase of the moon do lunar eclipses occur? full moon During a total lunar eclipse... The moon is completely in the umbra of the Earth's shadow and appears to be reddish in color. The angular size of the Moon in our sky will be ____ at the perigee and _____ at apogee greatest; smallest
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 A totally eclipsed moon glows coppery red because red light is better able to pass completely through Earth's atmosphere and reach the moon The angular size of the moon in our sky is __________ the angular size of the sun in our sky the same What phase of the moon is between the first quarter and full moon? waxing gibbous What is the phase of the moon 11 days after the new moon? waxing gibbous
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 How long does it take for the moon to rotate on its axis? 1 month The time it takes for the moon to revolve around the Earth and return to the same position among the stars is called a _________ month. sidereal based on everyday ideas of observation and experiments scientific thinking developed the first model of the solar system that made sufficiently accurate predictions of planetary positions ptolemy.
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 retrograde motion The apparent backward motion of a planet along the celestial sphere is called According to Copernicus' model of the solar system a planet undergoes retrograde motion when Earth passes the planet while they orbit Which of the statements below were not made by Copernicus in his formulation of a heliocentric model? Select one: a. What appears to be forward and retrograde motion of the planets is natrually due to their motion around us. b. The motions of the Sun are not its motions, but the motion of the Earth. c. The celestial spheres do not have just one common center. d. All of the spheres revolve around the Sun. A. What feature of Aristotle's model of the universe was included in the model proposed by Copernicus? uniform circular motion
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 parallax The apparent shift of a nearby object against the background of more distant stars is called ... detailed observations was a contribution by Tycho Brahe When Tycho observed the new star of 1572, he could detect no parallax. Why did that result undermine belief in the Ptolemaic system? This star is farther away than the moon and thus the heavens are not perfect and unchanging Galileo challenged the idea that objects in the heavens were perfect by observing mountains on the moon
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 In his observations of the planet Venus, what was seen by Galileo that could only be explained by Venus revolving around the Sun? a complete cycle of phases Galileo discovered that the planet Jupiter ... has moons orbiting it Kepler's 1st law states that the orbits of the planets are _____ with the _____ located _____ ellipse; sun; at one focus Where is the focus of an ellipse? Off center and along the longer axis
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 According to Kepler's 3rd Law, when compared to planets closer to the Sun, those farther away __________. take longer to revolve around the Sun According to Kepler's 2nd Law, at which position will a planet move fastest in its orbit around the Sun? perihelion Find the orbital period (in years) of an asteroid whose average distance from the sun is 20 A. U. What about 28 AU, 13 AU, and 6 AU? 90.….148, 47, and 14.5Calculator: http://www.calctool.org/CALC/phys/astronomy/planet_orbit ____ used his laws of motion and the Universal Law of Gravity to derive the orbits of the planets, thus explaining WHY the planets moved as they do... Newton
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 hypothesis A conjecture, subject to further tests, that accounts for a set of facts Galileo discovered that which planet undergoes phases as viewed from earth? Venus Parallax The apparent change in the position of an object because of the motion of the observer is called Which of the following were contained in both Ptolemy and Copernicus's models of the solar system. epicycles
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 Tycho used large metal instruments to accurately measure the positions of the planets kepler devised three laws of planetary motion copernicus made the first heliocentric model of the solar system ptolemy made geocentric model of the solar system using epicycles
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 newton used his universal laws of gravity to explain planetary motions Galileo discovered that jupiter has moons According to Kepler's 2nd Law, the planets move slowest when they are at which point in their orbit? aphelion planetary orbits that are more elliptical have a greater eccentricity
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 By using Kepler's 3rd Law we find that A year on Earth is shorter than a year on Saturn Light is a form of electromagnetic radiation photon a particle of light frequency the number of wave cycles that pass in one second
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 wavelength the distance between two successive peaks of a wave Red lights have ____ wavelength, _____ frequency, and travel at _____ speed compared to blue light waves when both are in space. longer; lower; the same. infrared light Light waves with a wavelength of 800 nm would be in which part of the electromagnetic spectrum Which two forms of electromagnetic radiation are useful for observing the stars from the ground? radio waves & visible
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 cycles per second units of frequency ____ telescope uses a large lens to gather and collect light refracting The large lens or mirror that is used to focus the light in a telescope is referred to as the primary lens What is caused by different colored lightwaves focusing in different places. For refracting telescopes-- chromatic aberration
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 eyepiece The small lens in a telescope that magnifies an image magnifying power The ability of a telescope to make an image appear larger the seeing refers to the atmospheric conditions on a given night light pollution The brightening of the night sky by light scattered from aritificial outdoor lighting
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 Which of the following best describes the focal length of a telescope? It is the distance from the lens or mirror to the image formed of a distant light source. What does resolving power measure? The angular size of the smallest features that can be viewed with the telescope What is a CCD? It is an electronic detector that can be used in place of photographic film for making images. Which of the following statements best describes the principle advantages of telescopes over eyes? Telescopes can collect far more light with far better angular resolution.
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 What is the purpose of adaptive optics? It reduces blurring caused by atmospheric turbulence for telescopes on the ground. The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see? the photo will only show 1 star. Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light? Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light. Which of the following is not an advantage of a telescope in space over ground-based telescopes? It is closer to the stars.
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 Which power of a telescope is the least important? magnifying power Which of the following effects is cause by atmospheric turbulence focus When light rays from a distant star pass through a lens they converge at a single point called the What process allows two or more small telescopes to achieve the angular resolution of a much larger telescope? interferometry
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 A telescope is used to take two images, one magnified 100x and the other magnified 400x. In which image would you be able to see the most detail and why? Neither. The angular size of the smallest features that a telescope can see is called the angular ... resolution The light collecting area of a telescope is larger in telescopes which have a larger …. diameter spectroscopy, imaging, timing. the three main categories of observation generally used by astronomers
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 Which telescopes use a mirror to gather and collect light? reflecting the largest telescope are reflecting telescopes Kelvin We measure the temperature of the stars using ... absolute zero The temperature at which no more heat energy can be extracted
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 Atoms contain three types of particles. In the nucleus there are positively charged _____ as well as ____ which have no charge. Orbiting the nucleus are negatively charged ____. Protons; neutrons; electrons. ground state The lowest possible energy level an electron can occupy excited state higher energy levels The chemical element of an atom is determined by the number of protons
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 Carbon-14 is an example of an isotope of Carbon. In this case, fourteen is the number of protons and neutrons Considering the transitions in a hydrogen atom, which transition results in the emission of a photon with the shortest wavelength? n=5 ---> n=1 An ion An atom that has fewer electrons than protons is called Which of the following can be determined by examining the spectrum of a star? surface temperature and chemical composition
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 According to the laws of thermal radiation, hotter objects emit photons with shorter wavelengths Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you? the wavelengths of spectral lines in the star's spectrum Which of the following statements is not true regarding the Sun? Spectral class of F2 What conditions produce an absorption line spectrum? light from a continuous spectrum source passing through a cooler low-density gas
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 Suppose that you take the spectra of several stars and identify the 656 nm line of hydrogen. You then measure against the reference spectrum on the same image and find that some of the 656 nm lines are shifted due to the Doppler effect. Of the following shifted locations of this line, which one is that of a star that is moving away from us at the highest speed? Star E at 659 nm If a certain star emits radiation that has a peak wavelength of 700 nm, the temperature of the star is ... equation is T= 0.0029/(nm)0.0029/700 = 4140 K (measured in Kelvin) In a vacuum, a blue photon has _____________ a red photon the same speed as The shifting of the observed wavelength of light due to the motion of the source toward or away from the observer is called the Doppler Effect
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 From examining the peak wavelength of the light emitted from a star we can determine the star's ... surface temperature photosphere The bright, visible surface of the Sun is called corona The outermost layer of the Sun's atmosphere is called chromosphere The layer of the solar atmosphere between the visible surface and the corona is called
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 granulation The mottled appearance of the Sun's surface caused by rising currents of hot gas and sinking currents of cooler gas is called sunspots blotches on the Sun's surface that appear darker than the surrounding regions prominences are composed of ionized gas trapped in a magnetic arch rising above the surface of the Sun.  When seen along the edge of the Sun, they appear pink in color.  However, when seen against the Sun's bright surface they appear as dark filaments. A violent eruption on the Sun's surface occuring when oppositely directed magnetic poles meet is called a solar ____ flare
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 The Sun's mass is about _________ times that of the Earth 300,000 What is caused by the effect known as limb darkening The Sun appears dimmer at the edge and brighter at the center The Sun's surface churns with a bubbling pattern called grannulation. Why? We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface What effect does the formation of negative hydrogen ions in the sun's photosphere have on solar observations? The extra electron absorbs different wavelength photons making the photosphere opaque
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 As one moves outward from the photosphere to the corona, what happens to the temperature and the density of the gases Temperature increases and density of the gases decrease. What is responsible for the sunspots on the Sun's surface? the sun's magnetic field What is the source of the sun's changing magnetic field? the differential rotation of the sun and convection beneath the photosphere. What is the net result of the proton-proton chain? 4 hydrogens are fused into 1 helium + energy
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 Which of the following formulas can be used the calculate the amount of energy produced by the mass lost during nuclear fusion? e =  m c2 The proton-proton chain is the specific set of nuclear reactions through which the Sun fuses hydrogen into helium What heats the chromosphere and corona to high temperatures? fluctuating magnetic fields from below that transport energy outward When examining a picture of the entire photosphere of the sun we see that The edge of the sun appears darker than the center
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 Which of the following describes the gases in the Sun's corona? hot and thin What particle do we detect coming directly from the solar interior? neutrino What is a coronal mass ejection? an event in which billions of tons of gas from the Sun is suddenly blasted into space at high speeds. Charged particles continually blown outward from the Sun in all directions make up the solar ______ wind
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 photosphere The disk of the Sun that we see The primary nuclear reaction providing energy inside the Sun's core converts …. hydrogen into helium How much time passes between two successive sunspot minima? 11 years a visual binary system in which both stars can be observed distinctly as they obit each other
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 OBAFGKM the spectral classes in order from hottest to coolest stellar parallax The angular shift of a star as seen from locations on Earth's orbit separated by one astronomical unit is referred to as that star's We can detect the binary nature of a ______ binary star system by the dopler shifts in its spectral lines. spectroscopic luminosity The total amount of energy a star radiates in one second is called
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 binary star system A pair of stars which orbit each other is called a eclipsing binary systems are detected by examining a light curve If Star A is closer to us than Star B, then Star A's stellar parallax is larger than that of Star B Ten parsecs is about 32.6 light years
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 According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples? its apparent brightness will decrease by a factor of 9 At what distance must a star be to have its apparent magnitude equal to its absolute magnitude 10 pc absolute bolometric magnitude Which magnitude gives the most information about the physical nature of a star A star has an apparent magnitude of 3.0 and is located at a distance of 2.5 pc. If this star were located at the standard distance of 10 pc, it would appear to be ______. Therefore its absolute magnitude will be ____. dimmer; greater
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 Colors of Stars from hottest to coolest Blue, White, Yellow, Orange, Red Stars with the same spectral class will have the same surface temperature Can a cool star be more luminous than a hot star? Yes, if the cool star is larger than the hot star. The axes on a Hertzsprung-Russell (H-R) diagram represent ____________. luminosity and surface temperature
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 The luminosity class of the star Alphard is II which means that it is a bright giant Two stars with the same luminosity class will have the same luminosity. T/F? FALSE A star has a stellar parallax of 0.15 seconds of arc. Find the distance to the star in light years. 21.8 CALCULATOR http://astro.unl.edu/classaction/animations/stellarprops/parallaxdiag.html What is the distance to a star that has an apparent magnitude of 1.5 and an absolute magnitude of -3.5? 100 pc
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 If a star has a large luminosity and also a low surface temperature then it must have ... larger radius the sun is its luminosity class main sequence To which group does the star Pollux belong? giants which has more mass, the Sun or Vega? Vega
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 If a star has a parallax of 0.25 arc seconds, what is the distance to that star? 4 parsecs Alan lives on a planet that is two times closer to a star than Zorg. Alan sees the star as being __________ than Zorg does. four times brighter A binary star system that is detected from Doppler shifted spectra is called ___________. spectroscopic hydrostatic equilibrium The condition where the weight of a star and the gas pressure are balanced is called
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 describes the gas pressures inside of stars The gas pressure is greatest at the center and decreases toward the star surface. The CNO cycle is a series of steps which occur in high mass stars that results in the fusion of hydrogen into helium Which stars produce most of their energy by the CNO cycle? upper main sequence stars Which of the following stars will spend the most time as a main sequence star? 1 solar-mass star
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 Which property of the star directly indicates the rate at which energy is produced inside that star? luminosity Why is there a lower mass limit of 0.08 solar-masses for main-sequence stars? Objects below this mass are not hot enough to fuse normal hydrogen Why is there an upper mass limit for main-sequence stars of about 100 solar masses? Objects above this mass fuse hydrogen too quickly and cannot stay together What percentage of a stars total fusion lifetime is spent as a main sequence star? 90%
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 Calculate many years will a star with a mass of 5 Msun spend on the main sequence? 0.179 billion years Calculate many years will a star with a mass of 2 Msun spend on the main sequence? 1.77 billi Calculate many years will a star with a mass of 0.7 Msun spend on the main sequence? 24.4 billion years Calculate many years will a star with a mass of 0.5 Msun spend on the main sequence? 56.6 billion
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 What happens when a main-sequence star exhausts its core hydrogen fuel supply? The core shrinks while the rest of the star expands. What is a helium flash? The sudden onset of helium fusion in the cores of some giant stars As the Sun leaves the main sequence to become a giant, its luminosity will ______ while its surface temperature ______ Increases; decreases. Which of the following is required in order for a helium flash to occur? a degenerate helium core
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 Which of the following describes a region with a diameter of 25pc containing anywhere between 10 and 1000 stars? open cluster What information about a star cluster can be obtained by examining its turn-off point on an H-R diagram? The age of the cluster Which of the following would be classified as an RR Lyrae variable? G Giant variable star Any star that changes its brightness in a periodic way is called
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 instability strip Any star located in the region of H-R diagram called the In terms of energy transport, what are the regions of the Sun's interior from the core outward core, radiation, convection Main sequence stars, such as the Sun, shine by _________ in their interiors converting carbon into helium What element is currently building up in the Sun's core? helium
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 As the sun becomes a red giant, its surface temperature will ________ while its luminosity will ___________. decrease; increase When the sun becomes a red giant, it will expand to approximately _______ its current radius. 100 times helium flash The nearly explosive beginning of helium burning in the dense core of red giant stars is called a A zero-age main-sequence star is one that can __________. sustain thermonuclear reactions in its core
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 Blue main sequence stars have ___________ than red main sequence stars. more mass and shorter lifetime planetary nebula is a shell of glowing ionized gas surrounding a dying star What is the maximum mass that a white dwarf could possibly have? 1.4 solar masses lighthouse model a neutron star is rotating sending out beams of radiation and when those beams are directed toward the Earth, we receive a pulse from the star.
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 pulsar A source of short precisely timed radio bursts believed to be a spinning neutron star is called a black hole An object compacted to such a small size that light cannot escape from its gravitational field is called a event horizon singularity All matter inside a black hole is theorized to be located at a single point at the very center of the black hole called the
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 Which of the following statments are true concerning the lowest mass main sequence stars, otherwise known as red dwarfs? none of them have ever evolved beyond the main sequence AND they will never become giant stars Which of the following forms when a slow stellar wind from a stars red giant stage is overtaken by a fast stellar wind from a newly exposed interior? planetary nebula White dwarfs are about the size of the Earth The interiors of white dwarfs are mainly composed of carbon and oxygen
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 Mass transfer in binary star systems occurs when one star expands beyond the size of its ... roche lobe Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system? planetary nebula Which event triggers the beginning of a supernova? The sudden collapse of an iron core into a compact ball of neutrons. What occurs when a white dwarf in a binary star system if it gains mass beyond the Chandrasekhar limit?
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 After a massive star produces a supernova explosion, the remains of the stellar core May be either a neutron star or a black hole Which of these is the same size as a typical neutron star? The extremely fast rotation speeds of neutron stars are a direct consequence of the conservation of angular momentum How would a person in the vicinity of a black hole appear to an observer far away? His time would be slower and his image more red.
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 When a star is oribiting a compact object, how can we tell if it's a neutron star, or black hole? In addition to the X-Rays, neutron stars will also emit detectable bursts of energy whereas black holes do not.
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## List View: Terms & Definitions

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Astronomical UnitThe average distance between the Earth and the Sun is defined as being one
Consider even the Earth and the Moon. About how many moons would fit across the Earth?4
The Earth's diameter is about 13,000 km while the distance between the Earth and the Moon is about 390,000 km. How many Earth's would fit between the Earth and the Moon?390000/13000= 30 times
What types of distances are typically listed in astronomical units?distances in solar system
What is a star, 1 AU from earth, and 100x diameter of earth?The Sun
List from Smallest to Largest: Milky Way, Solar System, Earth, GalaxiesEarth, Solar System, Milky Way, Galaxies
If the nearest star is 4.2 light-years away, then...the light we see left the star 4.2 years ago
3.9x105 is the same as390,000
Light takes about 8 minutes to travel from the Sun to Earth. Light takes about 40 minutes to travel from the Sun to Jupiter. How many astronomical units is Jupiter from the Sun?40 / 8 = 5
Light takes about 8 minutes to travel from the sun to Earth. Mars is approximately 1.5 AU from the Sun. How many light minutes is Mars from the Sun?8 x 1.5 = 12
If you were located on the boundary between daylight and darkness on the right side of the earth in this picture, would you be experiencing sunrise or sunset? Why?Sunset. Because Earth rotates counterclockwise when viewed from above Earth's North Pole.
A region of the sky containing a recognizable pattern of stars is called aConstellation
The apparent visual magnitudes of four stars are listed below. Of these four stars, which one appears dimmest in the sky?+ 2.8
If the apparent visual magnitude of a star is 7.3. This tells us that the star isNot visible to the naked eye
Objects A and B both have the same angular size, and Object A is closer to us than object B. Which of the following can we conclude?A < B
Proxima Centauri, the nearest star outside of our solar system, is about _______ times farther away from the Sun than Pluto7000
Universethe totality of all space, time, matter and energy.
10,000,000 is 10 raised to what?6
Milky Waythe galaxy we live in
Siriusthe brightest star in the night sky
Of the apparent visual magnitudes listed below, which corresponds to the faintest star in our sky that can still be seen with the naked eye?+ 4.5
The Big Dipper is the name of an...Asterism
What is the dividing the celestial sphere into northern and southern hemispherescelestial equator
Constellations that do not set and are always above our horizon are calledCircumpolar
HorizonThe imaginary boundary between the earth and sky
North celestial pole

The point on the celestial sphere directly above the north pole of the earth

South celestial polethe point on the celestial sphere directly above the south pole of the Earth
zenithThe point in the sky directly overhead of any observer
What is the celestial sphere?The celestial sphere is a representation of how the entire sky looks as seen from Earth
Suppose an astrophotographer hands you a picture with star trails taken looking toward the north celestial pole. If the star trails are 1/6 of a complete circle, about how many hours was the picture exposed?4 (24 hours * 1/6)
eclipticThe apparent path of the Sun through the constellations as viewed from Earth
autumnal equinoxthe sun is crossing the celestial equator moving south
vernal equinoxthe sun is crossing the celestial equator moving north
winter solsticethe sun is farthest south
summer solsticethe sun is farthest north
The sun appears on the equatoron equinoxes
precessionThe gradual wobble that changes the orientation of earth's axis
Will there be a zenith in Los AngelesNo. We are too far north.
Which of the following best describes why we have seasons on Earth?The tilt affects sunlight
The maximum tilt of the northern hemisphere toward the sun occurs on….the first day of summer
What is the angle between the earth's equator and the plane of the earth's orbit around the sun?23.5
Why is it summer in Los Angeles during June?the rays from the sun fall more directly on Los Angeles in June
The changing position of the North Celestial Pole over a 26,000 year period is due to the Earth'sprecession
ApogeeThe point on the moon's orbit farthest from Earth
perigeeThe point in the moon's orbit closest to the Earth
NodesThe points where the moon's orbit crosses the ecliptic
Saroscycle is the roughly 18-year cycle over which the pattern of eclipses repeats.
At about what time will the moon rise during a last quarter phase?midnight
What will the phase of the moon be 10 days after a first quarter moon?waning gibbous
Why we cannot see a new moon in our sky sometimesit is too close to the sun in our sky
The moon always shows nearly the same face toward earth becausethe Moon rotates once in the same amount of time that it takes the Moon to orbit Earth
synodic period

The time for the moon to repeat its cycle of phases is equal to its...

Full moon always occurs whenthe moon is directly opposite to the position of the sun
During which phase of the moon do lunar eclipses occur?full moon
By approximately how many degrees does the moon's position change from one day to the next?13
During which phase of the moon do lunar eclipses occur?full moon
During a total lunar eclipse...The moon is completely in the umbra of the Earth's shadow and appears to be reddish in color.
The angular size of the Moon in our sky will be ____ at the perigee and _____ at apogeegreatest; smallest
A totally eclipsed moon glows coppery red becausered light is better able to pass completely through Earth's atmosphere and reach the moon
The angular size of the moon in our sky is __________ the angular size of the sun in our skythe same
What phase of the moon is between the first quarter and full moon?waxing gibbous
What is the phase of the moon 11 days after the new moon?waxing gibbous
How long does it take for the moon to rotate on its axis?1 month
The time it takes for the moon to revolve around the Earth and return to the same position among the stars is called a _________ month.sidereal
based on everyday ideas of observation and experimentsscientific thinking
developed the first model of the solar system that made sufficiently accurate predictions of planetary positionsptolemy.

The apparent backward motion of a planet along the celestial sphere is called

According to Copernicus' model of the solar system a planet undergoes retrograde motion whenEarth passes the planet while they orbit
Which of the statements below were not made by Copernicus in his formulation of a heliocentric model? Select one: a. What appears to be forward and retrograde motion of the planets is natrually due to their motion around us. b. The motions of the Sun are not its motions, but the motion of the Earth. c. The celestial spheres do not have just one common center. d. All of the spheres revolve around the Sun.A.
What feature of Aristotle's model of the universe was included in the model proposed by Copernicus?uniform circular motion
parallax

The apparent shift of a nearby object against the background of more distant stars is called ...

detailed observationswas a contribution by Tycho Brahe
When Tycho observed the new star of 1572, he could detect no parallax. Why did that result undermine belief in the Ptolemaic system?This star is farther away than the moon and thus the heavens are not perfect and unchanging
Galileo challenged the idea that objects in the heavens were perfect byobserving mountains on the moon
In his observations of the planet Venus, what was seen by Galileo that could only be explained by Venus revolving around the Sun?a complete cycle of phases
Galileo discovered that the planet Jupiter ...has moons orbiting it
Kepler's 1st law states that the orbits of the planets are _____ with the _____ located _____ellipse; sun; at one focus
Where is the focus of an ellipse?Off center and along the longer axis
According to Kepler's 3rd Law, when compared to planets closer to the Sun, those farther away __________.take longer to revolve around the Sun
According to Kepler's 2nd Law, at which position will a planet move fastest in its orbit around the Sun?perihelion
Find the orbital period (in years) of an asteroid whose average distance from the sun is 20 A. U. What about 28 AU, 13 AU, and 6 AU?90.
….148, 47, and 14.5

Calculator: http://www.calctool.org/CALC/phys/astronomy/planet_orbit

____ used his laws of motion and the Universal Law of Gravity to derive the orbits of the planets, thus explaining WHY the planets moved as they do...Newton
hypothesisA conjecture, subject to further tests, that accounts for a set of facts
Galileo discovered that which planet undergoes phases as viewed from earth?Venus
ParallaxThe apparent change in the position of an object because of the motion of the observer is called
Which of the following were contained in both Ptolemy and Copernicus's models of the solar system.epicycles
Tychoused large metal instruments to accurately measure the positions of the planets
keplerdevised three laws of planetary motion
copernicusmade the first heliocentric model of the solar system
ptolemymade geocentric model of the solar system using epicycles
newtonused his universal laws of gravity to explain planetary motions
Galileo discovered that jupiter hasmoons
According to Kepler's 2nd Law, the planets move slowest when they are at which point in their orbit?aphelion
planetary orbits that are more elliptical have a greatereccentricity
By using Kepler's 3rd Law we find thatA year on Earth is shorter than a year on Saturn
Light is a form of
photona particle of light
frequencythe number of wave cycles that pass in one second
wavelengththe distance between two successive peaks of a wave
Red lights have ____ wavelength, _____ frequency, and travel at _____ speed compared to blue light waves when both are in space.longer; lower; the same.
infrared light

Light waves with a wavelength of 800 nm would be in which part of the electromagnetic spectrum

Which two forms of electromagnetic radiation are useful for observing the stars from the ground?radio waves & visible
cycles per secondunits of frequency
____ telescope uses a large lens to gather and collect lightrefracting
The large lens or mirror that is used to focus the light in a telescope is referred to as theprimary lens
What is caused by different colored lightwaves focusing in different places.For refracting telescopes-- chromatic aberration
eyepieceThe small lens in a telescope that magnifies an image
magnifying powerThe ability of a telescope to make an image appear larger
the seeingrefers to the atmospheric conditions on a given night
light pollutionThe brightening of the night sky by light scattered from aritificial outdoor lighting
Which of the following best describes the focal length of a telescope?It is the distance from the lens or mirror to the image formed of a distant light source.
What does resolving power measure?The angular size of the smallest features that can be viewed with the telescope
What is a CCD?It is an electronic detector that can be used in place of photographic film for making images.
Which of the following statements best describes the principle advantages of telescopes over eyes?Telescopes can collect far more light with far better angular resolution.
What is the purpose of adaptive optics?It reduces blurring caused by atmospheric turbulence for telescopes on the ground.
The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?the photo will only show 1 star.
Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light.
Which of the following is not an advantage of a telescope in space over ground-based telescopes?It is closer to the stars.
Which power of a telescope is the least important?magnifying power
Which of the following effects is cause by atmospheric turbulence
focusWhen light rays from a distant star pass through a lens they converge at a single point called the
What process allows two or more small telescopes to achieve the angular resolution of a much larger telescope?interferometry
A telescope is used to take two images, one magnified 100x and the other magnified 400x. In which image would you be able to see the most detail and why?Neither.
The angular size of the smallest features that a telescope can see is called the angular ...resolution
The light collecting area of a telescope is larger in telescopes which have a larger ….diameter
spectroscopy, imaging, timing.the three main categories of observation generally used by astronomers
Which telescopes use a mirror to gather and collect light?reflecting
the largest telescope arereflecting telescopes
KelvinWe measure the temperature of the stars using ...
absolute zeroThe temperature at which no more heat energy can be extracted
Atoms contain three types of particles. In the nucleus there are positively charged _____ as well as ____ which have no charge. Orbiting the nucleus are negatively charged ____.Protons; neutrons; electrons.
ground stateThe lowest possible energy level an electron can occupy
excited statehigher energy levels
The chemical element of an atom is determined by the number ofprotons
Carbon-14 is an example of an isotope of Carbon. In this case, fourteen is the number ofprotons and neutrons
Considering the transitions in a hydrogen atom, which transition results in the emission of a photon with the shortest wavelength?n=5 ---> n=1
An ionAn atom that has fewer electrons than protons is called
Which of the following can be determined by examining the spectrum of a star?surface temperature and chemical composition
According to the laws of thermal radiation, hotter objects emit photons withshorter wavelengths
Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?the wavelengths of spectral lines in the star's spectrum
Which of the following statements is not true regarding the Sun?Spectral class of F2
What conditions produce an absorption line spectrum?light from a continuous spectrum source passing through a cooler low-density gas
Suppose that you take the spectra of several stars and identify the 656 nm line of hydrogen. You then measure against the reference spectrum on the same image and find that some of the 656 nm lines are shifted due to the Doppler effect. Of the following shifted locations of this line, which one is that of a star that is moving away from us at the highest speed?Star E at 659 nm
If a certain star emits radiation that has a peak wavelength of 700 nm, the temperature of the star is ...equation is T= 0.0029/(nm)
0.0029/700 = 4140 K (measured in Kelvin)
In a vacuum, a blue photon has _____________ a red photonthe same speed as
The shifting of the observed wavelength of light due to the motion of the source toward or away from the observer is called theDoppler Effect
From examining the peak wavelength of the light emitted from a star we can determine the star's ...surface temperature
photosphereThe bright, visible surface of the Sun is called
coronaThe outermost layer of the Sun's atmosphere is called
chromosphereThe layer of the solar atmosphere between the visible surface and the corona is called
granulationThe mottled appearance of the Sun's surface caused by rising currents of hot gas and sinking currents of cooler gas is called
sunspotsblotches on the Sun's surface that appear darker than the surrounding regions
prominencesare composed of ionized gas trapped in a magnetic arch rising above the surface of the Sun.  When seen along the edge of the Sun, they appear pink in color.  However, when seen against the Sun's bright surface they appear as dark filaments.
A violent eruption on the Sun's surface occuring when oppositely directed magnetic poles meet is called a solar ____flare
The Sun's mass is about _________ times that of the Earth300,000
What is caused by the effect known as limb darkeningThe Sun appears dimmer at the edge and brighter at the center
The Sun's surface churns with a bubbling pattern called grannulation. Why?We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface
What effect does the formation of negative hydrogen ions in the sun's photosphere have on solar observations?The extra electron absorbs different wavelength photons making the photosphere opaque
As one moves outward from the photosphere to the corona, what happens to the temperature and the density of the gasesTemperature increases and density of the gases decrease.
What is responsible for the sunspots on the Sun's surface?the sun's magnetic field
What is the source of the sun's changing magnetic field?the differential rotation of the sun and convection beneath the photosphere.
What is the net result of the proton-proton chain?4 hydrogens are fused into 1 helium + energy
Which of the following formulas can be used the calculate the amount of energy produced by the mass lost during nuclear fusion?e =  m c2
The proton-proton chain isthe specific set of nuclear reactions through which the Sun fuses hydrogen into helium
What heats the chromosphere and corona to high temperatures?fluctuating magnetic fields from below that transport energy outward
When examining a picture of the entire photosphere of the sun we see thatThe edge of the sun appears darker than the center
Which of the following describes the gases in the Sun's corona?hot and thin
What particle do we detect coming directly from the solar interior?neutrino
What is a coronal mass ejection?an event in which billions of tons of gas from the Sun is suddenly blasted into space at high speeds.
Charged particles continually blown outward from the Sun in all directions make up the solar ______wind
photosphereThe disk of the Sun that we see
The primary nuclear reaction providing energy inside the Sun's core converts ….hydrogen into helium
How much time passes between two successive sunspot minima?11 years
a visual binarysystem in which both stars can be observed distinctly as they obit each other
OBAFGKMthe spectral classes in order from hottest to coolest
stellar parallaxThe angular shift of a star as seen from locations on Earth's orbit separated by one astronomical unit is referred to as that star's
We can detect the binary nature of a ______ binary star system by the dopler shifts in its spectral lines.spectroscopic
luminosityThe total amount of energy a star radiates in one second is called
binary star systemA pair of stars which orbit each other is called a
eclipsing binary systemsare detected by examining a light curve
If Star A is closer to us than Star B, then Star A's stellar parallax is larger than that of Star B
Ten parsecs is about32.6 light years
According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples?its apparent brightness will decrease by a factor of 9
At what distance must a star be to have its apparent magnitude equal to its absolute magnitude10 pc
absolute bolometric magnitudeWhich magnitude gives the most information about the physical nature of a star
A star has an apparent magnitude of 3.0 and is located at a distance of 2.5 pc. If this star were located at the standard distance of 10 pc, it would appear to be ______. Therefore its absolute magnitude will be ____.dimmer; greater
Colors of Stars from hottest to coolestBlue, White, Yellow, Orange, Red
Stars with the same spectral class will have the samesurface temperature
Can a cool star be more luminous than a hot star?Yes, if the cool star is larger than the hot star.
The axes on a Hertzsprung-Russell (H-R) diagram represent ____________.luminosity and surface temperature
The luminosity class of the star Alphard is II which means thatit is a bright giant
Two stars with the same luminosity class will have the same luminosity. T/F?FALSE
A star has a stellar parallax of 0.15 seconds of arc. Find the distance to the star in light years.21.8

CALCULATOR http://astro.unl.edu/classaction/animations/stellarprops/parallaxdiag.html

What is the distance to a star that has an apparent magnitude of 1.5 and an absolute magnitude of -3.5?100 pc
If a star has a large luminosity and also a low surface temperature then it must have ...larger radius
the sun is its luminosity classmain sequence
To which group does the star Pollux belong?giants
which has more mass, the Sun or Vega?Vega
If a star has a parallax of 0.25 arc seconds, what is the distance to that star?4 parsecs
Alan lives on a planet that is two times closer to a star than Zorg. Alan sees the star as being __________ than Zorg does.four times brighter
A binary star system that is detected from Doppler shifted spectra is called ___________.spectroscopic
hydrostatic equilibriumThe condition where the weight of a star and the gas pressure are balanced is called
describes the gas pressures inside of starsThe gas pressure is greatest at the center and decreases toward the star surface.
The CNO cycle is a series of steps which occur in high mass stars that results in the fusion ofhydrogen into helium
Which stars produce most of their energy by the CNO cycle?upper main sequence stars
Which of the following stars will spend the most time as a main sequence star?1 solar-mass star
Which property of the star directly indicates the rate at which energy is produced inside that star?luminosity
Why is there a lower mass limit of 0.08 solar-masses for main-sequence stars?Objects below this mass are not hot enough to fuse normal hydrogen
Why is there an upper mass limit for main-sequence stars of about 100 solar masses?Objects above this mass fuse hydrogen too quickly and cannot stay together
What percentage of a stars total fusion lifetime is spent as a main sequence star?90%
Calculate many years will a star with a mass of 5 Msun spend on the main sequence?0.179 billion years
Calculate many years will a star with a mass of 2 Msun spend on the main sequence?1.77 billi
Calculate many years will a star with a mass of 0.7 Msun spend on the main sequence?24.4 billion years
Calculate many years will a star with a mass of 0.5 Msun spend on the main sequence?56.6 billion
What happens when a main-sequence star exhausts its core hydrogen fuel supply?

The core shrinks while the rest of the star expands.

What is a helium flash?The sudden onset of helium fusion in the cores of some giant stars
As the Sun leaves the main sequence to become a giant, its luminosity will ______ while its surface temperature ______Increases; decreases.
Which of the following is required in order for a helium flash to occur?a degenerate helium core
Which of the following describes a region with a diameter of 25pc containing anywhere between 10 and 1000 stars?open cluster
What information about a star cluster can be obtained by examining its turn-off point on an H-R diagram?The age of the cluster
Which of the following would be classified as an RR Lyrae variable?G Giant
variable starAny star that changes its brightness in a periodic way is called
instability stripAny star located in the region of H-R diagram called the
In terms of energy transport, what are the regions of the Sun's interior from the core outwardcore, radiation, convection
Main sequence stars, such as the Sun, shine by _________ in their interiorsconverting carbon into helium
What element is currently building up in the Sun's core?helium
As the sun becomes a red giant, its surface temperature will ________ while its luminosity will ___________.decrease; increase
When the sun becomes a red giant, it will expand to approximately _______ its current radius.100 times
helium flashThe nearly explosive beginning of helium burning in the dense core of red giant stars is called a
A zero-age main-sequence star is one that can __________.sustain thermonuclear reactions in its core
Blue main sequence stars have ___________ than red main sequence stars.more mass and shorter lifetime
planetary nebulais a shell of glowing ionized gas surrounding a dying star
What is the maximum mass that a white dwarf could possibly have?1.4 solar masses
lighthouse modela neutron star is rotating sending out beams of radiation and when those beams are directed toward the Earth, we receive a pulse from the star.
pulsarA source of short precisely timed radio bursts believed to be a spinning neutron star is called a
black holeAn object compacted to such a small size that light cannot escape from its gravitational field is called a
event horizon
singularityAll matter inside a black hole is theorized to be located at a single point at the very center of the black hole called the
Which of the following statments are true concerning the lowest mass main sequence stars, otherwise known as red dwarfs?none of them have ever evolved beyond the main sequence AND they will never become giant stars
Which of the following forms when a slow stellar wind from a stars red giant stage is overtaken by a fast stellar wind from a newly exposed interior?planetary nebula
White dwarfs are about the size ofthe Earth
The interiors of white dwarfs are mainly composed ofcarbon and oxygen
Mass transfer in binary star systems occurs when one star expands beyond the size of its ...roche lobe
Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system?planetary nebula
Which event triggers the beginning of a supernova?The sudden collapse of an iron core into a compact ball of neutrons.
What occurs when a white dwarf in a binary star system if it gains mass beyond the Chandrasekhar limit?
After a massive star produces a supernova explosion, the remains of the stellar coreMay be either a neutron star or a black hole
Which of these is the same size as a typical neutron star?
The extremely fast rotation speeds of neutron stars are a direct consequence of theconservation of angular momentum
How would a person in the vicinity of a black hole appear to an observer far away?His time would be slower and his image more red.
When a star is oribiting a compact object, how can we tell if it's a neutron star, or black hole? In addition to the X-Rays, neutron stars will also emit detectable bursts of energy whereas black holes do not.