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ASTR MIdterm 1
| Question | Answer |
|---|---|
| What is the scientific method? Compared to the other way of doing things? | question, hypothesis, experiment, analyze data, draw conclusions, publish results, retest - peer, repeat. QHEDCPRR. |
| How do you do Science? By experiement | By experiment |
| How and what are longitude and Latitude? | Longitude are the lines from pole to pole, or meridians measuring north and south. Latitude lines are lines parallel to the equator measuring east and west. |
| What is Declination? | It is like Latitude. EAST and WEST. The horizontal lines along the celestial sphere that are measured in degree's. -90 degrees, to 90 degrees. |
| What is Right Ascension? | Right Ascension / longitude is measured hours and degrees. Measureoutward along the celestial equator, starting from zero hour, or the Vernal Equinox. The Horizontal lines along the celestial sphere that is measured in hours and minutes. NORTH and SOUTH. |
| How does the sun move? | |
| Explain the equinox, with respect to the sun? | |
| What is the Meridian of the Earth? | |
| How are light waves distinguished? | By their lengths |
| What is a wavelength? | The distance from any point on the wave to the next identical point, such as crest to crest, or trough to trough. |
| How many wavelengths are there in visible light? | 4000 to 7000 "A" or (A = angstrom unit) |
| Which color light has the shortest wavelength? | Violet, it has a shorter wavelength and higher frequency, higher energy. It has more bursts of energy hitting you. |
| Which color light has the longest wavelength? | Red, it has the longest wavelength, and the low frequency, energy. Less bursts. |
| To which wavelength (color) is the eye most sensitive? | Yellow-green |
| What is a wave? | A rising and falling disturbance that transports energy from a source to a receiver without the actual transfer of material. |
| What is a light wave? | an electromagnetic disturbance consisting of rapidly varying electric and magnetic effects. Light waves transport energy from accelerating electric charges in stars (source) to electric charges in the retina of your eye (the receiver) |
| What is the electromagnetic spectrum? | The whole family of electromagnetic waves arranged according to wavelength. |
| List six forms of electromagnetic radiation from the shortest waves (highest energy) to the longest waves (lowest energy) | Gamma rays, X-Rays, ultraviolet radiation, visible light, infrared radiation, radio waves. |
| How can we describe a wave motion? | Wave motion can be described in terms of a frequency as well as a wavelength. |
| What is the frequency of a wave motion? | The frequency of a wave motion is the number of waves that pass by a fixed point at any given time. |
| How is frequency measured? | CPS - Cycles per second. |
| how are radio waves measured and what is that called? | Radio waves are once cycle per second, called "Hertz" |
| What are higher frequency waves? | Gamma Rays, X-Rays, Ultra Violet Waves |
| What are lower frequency waves? | Infrared radiation, microwaves, radio-waves, submillimeter waves. |
| ## What is the general relationship between the wavelength and frequency for the electromagnetic waves? | The wavelength is inversely proportional to the frequency. The shorter waves have a relatively higher frequency, and the longer waves have a relatively longer frequency. |
| How do we calculate the speed of a wave? | Frequency X Wavelength |
| Do all wavelengths have the same speed in empty space? | Yes. All electromagnetic waves have the same speed in empty space. That is, the speed of light, or about 300, 000 KM/ second. (186, 000) miles per second. |
| For electromagnetic wavelengths, what is the formula? | Speed = C, Frequency = F, Wavelength = h (or something that looks kinda like that) |
| Calculate the wavelength of a radio wave whose frequency is 100 KHz (100, 000) miles per second) | Speed = frequency X wavelength. Wavelength = Speed over frequency. .means WL = speed / frequency. We know the speed of light is 300,00 km or 186, 000 miles per second. So, 300,000 KM / per second / 100, 000 cycles per second = 3 KM, or (1.86) |
| What is sidereal time? | it is star time, unlike solar time that measurs a 24 hour a day, or the time it tkes for the earth to revolve around the sun. Sidereal time is the amount of time it takes a start to revolve around, which is 4 minutes shorter than the sun. 23.56. |
| What is the ecliptic? | The apparent path of the sun against the background stars. |
| What is the vernal equinox? | occurs about March 20th, is the suns position as it crosses the celestial equator going north. |
| What is the Zenith? | The point on the celestial sphere directly over your head. |
| What is the ecliptic? | It is the name of the plane that contains the orbit of the Earth and other planets around the sun. It appears as though the sun moves on a path across the sky throughout the year, along the ecliptic. |
| What is the prime meridian? | It is a line that runs from pole to pole, through Greenwich, England, that divides the celestial globe in half. |
| How many constellations are there? | 88 |
| What are the most famous constellations? | There are 12 famous constellations that are located in a band around the eclliptic, called the Zodiac. And, the sun appears to move through each of these constellations over the course of one year. |
| What is the order of the constellations? | Start with Leo then work your way around. I already know the constellations. |
| What is the Zodiac? | A belt about 16 degrees wide around the sky, centered on the ecliptic, containing the 12 most famous constellations that are 30 degree sections. |
| For purpose of the test, what are the constellations on the zodiac as labeled in the book diagram on page 22? | From apparent sun number 1: Sagittarius, Capricornus. Above, after apparent sun #2, Pisces, Aries, Taurus, Gemini, Leo. |
| How much does the sun move on the ecliptic every day? | 1 degree. |
| What does the constellation Leo look like? | Kind of looks like a backwards iron. Mars is in Leo. If you can locate Mars, then you can locate, Leo. Constellation Leo is best seen in early spring when it is high in the sky, the brightest star in leo is Regulus and it marks the lions heart. |
| Give the celestial name for equator? | Celestial equator |
| Give the celestial name for North Pole? | North Celestial Pole. |
| Give the celestial name for South pole? | South Celestial Pole. |
| Give the celestial name for Latitude? | Declination. DEC = EW |
| Give the celestial name for Longitude? | Right Ascension. RA = NS |
| What else is a name for Greenwich, England? | Vernal Equinox |
| Which are the brightest stars in the sky are above the celestial equator? | Arcturus and Vega |
| Which are the brightest stars in the sky are below the celestial equator? | Sirius, Canopus, Rigil |
| Which of the five brightest stars never appear above the horizon at latitude 40 degrees. | Canopus, Rigil |
| When a light wave travels in time to the right, what does it transport? | energy |
| What is the brightest star in Earth's sky? | Sirius |
| Name the three brightest stars that mark the points of the famous summer triangle. | Vega, Deneb, and Altair. |
| What is apparent Magnitude? | How bright a sky object looks. |
| What is the formula for the speed of light? | C = 3 x 10 ^8 Meters per second. |
| Does anything move faster than the speed of light? | No |
| What does light transport and how much? | energy, and it depends on the wavelength |
| Does light slow down when passing through material like glass or water? | Yes, it slows down slightly. |
| What does LY measure? | Light years. The distance traveled by light through empty space in 1 year. |
| What is the distance in meters traveled by light in 1 year? | 1 year = 3.156 x 10 ^7 seconds. Speed = distance X time. H |
| How much time does it take for light to travel from the surface of the sun to the Earth? Speed = distance x time. solve in seconds, convert to minutes. Speed = 3 x 10^8 m, Distance = 1.5 x 10^11 m | 1.5 x 10^11 M / 3 x 10 ^8 M = 1.5 / 3 x 10 11-8, 1.5 /3 x 10^3, .5 x 10^3, .5 x 10^3-1, 5 x 10^2, 10^2 =100 minutes, 5 x 100 = 500 minutes. 500 minutes / 60 seconds = 8.3 |
| Why do we have a change of seasons? | Due to the motion of the earth around the sun. The earth revolves around the sun every year. |
| Why is a solar day about four minutes longer than a sidereal day? | A solar day measures the time interval of the earth's rotation using the sun for a reference and the sidereal day measures the time interval using the Earth's rotation around the stars. |
| Where would you have to stand on Earth to have the sun pass directly across your zenith at the time of the Vernal Equinox? | Equator |
| Where would you have to stand on Earth to have the sun pass directly across your zenith at the time of the Summer Solstice? | 23.5 degrees North |
| Where would you have to stand on Earth to have the sun pass directly across your zenith at the time of the Autumnal equinox? | equator |
| Where would you have to stand on Earth to have the sun pass directly across your zenith at the time of the Winter Solstice? | 23.5 degrees South |
| How long is a Sidereal Day? | 23 hours and 56 Minutes |
| How long is a solar day? | 24 hours. |
| Why does light have a dual behavior? | Because it behaves like a particle (photon) and a wave, and electromagnetic wave. |
| What are three names for light? | Photon, Electromagnetic wave, Electromagnetic radiation. |
| Is Space like a Vacuum? | Yes, space is like a vacuum. |
| How are different wavelengths of light perceived? | As different colors. |
| What are the angles in the LOCAL coordinate system called the Horizon System? | Azimuth and Altitude |
| What is a fixed coordinate system? | equatorial system |
| What are the two angels in the equatorial system? | Right Ascension and declination |
| What is a Nano? | 10^-9 |
| What is the wave equation? | C = F x A (A = wavelength for electromagnetic waves) |
| State what all electromagnetic waves have in common? | all electromagnetic waves travel through empty space at the same speed, the speed of light - about 300, 000 KM or 186, 000 miles per second. Thus, we stars as they were many years ago. |
| Write the general formula that relates the wavelength and the frequency of a wave? | C = A (wavelength) = speed of wave / frequency |
| Suppose you observe a bluish star and a reddish star, state which is hotter and explain how you know? | The bluish star is hotter. The shorter the wavelength which a start emits its maximum light, the hotter the star, according to Wien's law of radiation. Blue light has a shorter wavelength than red light. |
| What is a Blackbody? | An object that absorbs all wavelengths of light incident upon it and remits energy at a characteristic peak wavelength depending on the objects temperature. |
| As the blackbody temperature increases what happens to the wavelength? | The maximum of intensity shifts to shorter wavelengths. |
| Can a stars color tell the surface temperature? | Yes, the color of a star can tell the surface temp. |
| What is Wein's Law equation? | λmax =0.3cm*K/T |
| What is Wein's Law equation? | where T is temperature measured in Kelvins, and λmax is the peak wavelength of the blackbody in centimeters. |
| What is the Stefan Boltzmann Law? | E O (= proportional to) T4. where E is the total energy emitted by a blackbody and T is its surface temperature (_ means “proportional to”) |
| What are the only (2) types of radiation that can fully penetrate the Earth's atmosphere and reach the ground? | Visible light and radio waves |
| what are the approximate light waves traveling through space as straight lines called? | Light Rays. |
| What is “Aperture”? | The size of a lens or mirror refers to the diameter of its circular shape and it is the word used for this diameter. |
| What is the focal length? | is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror; the point where parallel rays of light meet, or converge to form an image |
| What are the three powers of a telescope? | Light collecting power, Resolving power, magnification power. |
| What is a light collecting power of a telescope? | Area of a circle = (π D2)/4, where D is the diameter → Larger diameter means that more light is collected hence fainter stars can be seen; depends on D2 |
| What is the resolving power of a telescope? | Larger diameter means sharper image; depends on D. The limit of how sharp the image from a telescope can be is called the resolving power. |
| What is the magnification power of a telescope? | The amount of magnification is given by the ratio of the focal lengths: M = f telescope / f eyepiece |
| What else is the light collecting power of a telescope? | Depends on aperture size of mirror/lens A bigger aperture means more area to collect light which means fainter objects can be seen Areaofacircle=πD2 /4 where D is the diameter of a circular mirror |
| What else can be said of a resolving power of a telescope? | * Look at 2 stars closer and closer together. When the telescope sees only one instead of two stars you have reached the resolving limit. * A telescope with a larger aperture has better resolving power. |
| What else can be said of a magnification telescope? | The amount of magnification is given by the ratio of the focal lengths: M = f telescope / f eyepiece Example: Our Celestron telescopes f telescope = 2000 mm f eyepiece =12mm Thus, the magnification is M = (2000 mm) / (12mm) ≈ 160 times larger |
| What is a chromatic aberration? | a lens defect; different colors are not focused at the same point |
| Where is the "World's Largest Telescope"? | Lick Observatory San Jose, CA 91 cm lens (almost a meter) circa 1905 |
| What is a telescopes magnifying power? | the ratio of the apparent size of an object seen through the telescope to its size when seen with the eye alone. Magnifying power = Focal length of a telescope / focal length of the eyepiece. |
| What are the three types of spectra? | Continuos spectra, absorption, emission. |
| What is the worlds largest optical telescope? | OPTICAL - Great Canary Telescope. Mirror = 10.4 meters across. 2007 |
| The Future of World's Largest Telescope? | OPTICAL- 30 meter mirror. Hawaii. 2020 |
| What does the Wein's law equation mean? | The wavelength at which a blackbody emits the greatest amount of radiation is inversely proportional to it's temperature T. |
| What is a refracting telescope? | LENS> Has a main objective lens permanently mounted at the front end of the tube. eye looks through the back. Starlight enters this lens and is refracted or bent so that it forms an image near the back of the tube. |
| What is a reflecting telescope? | MIRROR. Has a highly polished curved glass mirror, the primary mirror mounted at the bottom of an open tube. When starlight shines on the mirror it is reflected back up the tube to form an image at the "prime focus" |
| What is the essential difference between a reflecting telescope and a refracting telescope? | The main optical part (objective). A reflecting telescope uses a mirror, whereas a refracting telescope uses a lens to collect light and focus starlight. |
| What does a "150 mm, F/8 reflector mean? | The primary MIRROR is 150 mm in diameter and has a focal length of 8 x 150, or 1200 mm. |
| Radio telescopes that measure radio waves? | They work during the day. Arecibo, Puerto Rico; The Very Large Array (VLA) in New Mexico |
| What telescopes are in space measuring infrared? | Hubble Space Telescope (optical & near infrared; Future: James Webb Telescope (infrared), NASA's Spitzer Space Telescope observed in the infrared part of the electromagnetic; Herschel Telescope |
| Future worlds largest optical telescope? Just to out - do Hawaii | European Extremely Large Telescope(EELT) 40 meter mirror! (by 2020?) |
| What kind of light must a telescope go to space to measure? | Ultraviolet, X-Ray, Gamma Ray |
| What are Wave Equation and Radiation laws (i.e., light laws) | Blackbody radiation curves ** Wien's law: peak wavelength & temperature ** Stefan-Boltzmann law: energy & temperature |
| Blackbody light laws = | radiation curves |
| Wien's law = | peak wavelength & temperature |
| Stefan-Boltzmann law: | energy & temperature |
| Only visible light & radio waves can completely reach Earth's surface; | these are the “atmospheric windows” |
| Spitzer Telescope = | Infrared light (long to med waves) |
| Hubble telescope = | Visible light (med waves) |
| XMM Newton telescope = | X - Ray, maybe ultraviolet, not sure. (mid short waves) |
| Femi Telescope = | Gamma Ray (shortest waves) |
| Astronomical observations goal is to? | Collect light |
| What does the Stefan Boltzmann radiation law state? | That the total energy (E) emitted by a blackbody is proportional to the fourth power of it's absolute temperature (T). Thus a star that is twice as hot as our sun radiates 2^4 or 16 times more energy than the sun. |
| What does a radiation spectrum show? | how much energy a body radiates at different wavelenths, which wavelengths it radiates most intensely and the total amount of energy it radiates at all wavelengths (indicated by the area under the curve) |
| What wavelength does the sun radiate most intensely? | In the visible wavelength. |
| The total amount of energy that the sun radiates as visible light is more or less than the amount radiated outside the visible region? | Less |
| Ground based astronomers look out at the universe through what kind of windows and how many? What are they? | Atmospheric windows..there are two. these are there the optical / visible light including some infrared and radio windows. |
| What does an optical telescope do? | forms images of faint and distant stars. |
| Spherical Aberration | Mirror defect that blurs a star's image. A parabolic mirror avoids this defect. IT's paraboloid shape is curved less at the edges than at the center, and so it properly reflects starlight to a single focus. |
| Adaptive optics | is a technique that allows ground-based telescopes to remove the blurring affects caused by Earth's atmosphere. |
| In the Blackbody radiation curve the blue star is? | Hottest stars are blue and white - they have the shortest wavelength |
| In the Blackbody radiation curve the red star is? | The coolest stars are red - they have the longest wavelenths. |
| Is the Gamma Ray a short or long wavelenth? | It is shorter than UV. |
| What does the Blackbody curve mean? | This means that the black-body curve is the amount of light energy emitted by a black body. the black-body curve is characteristic of thermal light, which depends only on the temperature of the walls of the cavity. |
| All objects with a temperature above absolute zero (0 K, -273.15 oC) emit energy in the form of electromagnetic radiation. | True |
| A blackbody is | a theoretical or model body which absorbs all radiation falling on it, reflecting or transmitting none. It is a hypothetical object which is a “perfect” absorber and a “perfect” emitter of radiation over all wavelengths. |
| Planck’s Law of blackbody radiation | a formula to determine the spectral energy density of the emission at each wavelength (Eλ) at a particular absolute temperature (T). |
| The Blackbody of a radiation curve is a plot of? | Wavelength on the horizontal axis and temperature on the vertical axis. |
| What is transported by a light wave? | energy |
| What types of radiation are best observed on Earth? | Visible and Radio |
| Starting with the shortest wavelength, which is the correct order of visible light? | Violet, indigo, blue, green, yellow, orange, red |
| Water boils at what Temp? | 212 F, 100 C, 373 Kelvins |
| Water Freezes at what temp? | 273 Kelvins, 0 degrees C, and 32 degrees F. |
| What are the numbers for Absolute zero? | zero kelvins, - 273 C, -460 F. |
| OBAFGKMLT | Oh Be A Fine Girl Kiss Me Love To |
| What are Stellar Spectra? | Spectrums of stars or absorption spectrums |
| radial velocity | The Doppler shift of spectral lines detects the |
| If moving away from us, lines are? | Redshifted |
| If moving toward us, lines are? | Blueshifted |
| What is AU and what does it measure? | Astronomical Unit”. |
| The average distance from Earth to the Sun is defined as? | 1 AU |
| Our solar system is about ? in diameter | 100 AU |
| Apparent magnitudes (m) measure a star's? | apparent brightness (small or negative numbers indicate brighter stars |
| Absolute magnitudes (M) measure a star's intrinsic brightness? | defined as the apparent magnitude a star would have if it were located at a fixed distance of 10 parsecs from Earth |
| What is the amount of light collected by a telescope? | depends on the area of the telescope's mirror/lens. Area of a circle = πD2/4 |
| What does the study of light lets us measure? | Temperature, Chemical Composition, Relative speed of the object. |
| What is an Atom? | the smallest particle of a chemical element, and it contains even smaller particles (electrons, protons, neutrons). |
| What are atoms responsible for? | each type of spectra |
| What is excitation? | The process of an electron in an atom absorbing a photon. After absorbing a photon the electron (and by extension the atom) is said to be in an excited energy state. If the right energy is supplied, an electron will jump to a higher energy level. |
| When are bright colored energy lines produced? | When electrons jump from higher energy levels back down to lower energy levels. |
| What is emission spectra? | At each DOWNWARD jump, the emitted photon carries an energy equal to the difference between the energies of the initial and final energy levels. Bright colored emission lines are produced when electrons jump from high energy levels back down to lower EL. |
| What is absorption spectra? | Electrons jump up levels and absorb photons that carry the exact amount of energy needed for the electrons to move up to higher energy levels |
| What are spectral Lines? | a result of electrons jumping to different energy levels within an atom. |
| What are the hottest stars in the Spectral class? | O for bluish - white stars. |
| What are the coldest stars in the Spectral Class? | M for red stars. L & T are even colder. |
| What are most stars composed of? | Hydrogen and Helium |
| What makes the difference in a stars dark line patterns? | Surface temperatures. |
| Does the absence of the characteristic absorption lines of a particular element like hydrogen in a stars spectrum necessarily mean that the star does not contain that element? | No. The stars temperature determines which kinds of atoms can produce visible absorption lines. |
| List three properties of a star connected to its spectral line shape? | Density, axil motion, magnetic field strength. |
| What does the sun look so much brighter than Deneb? | Deneb is 95 million times farther away from Earth than the sun. A stars apparent brightness depends on both its luminosity and its distance from us. |
| Why do we use Scientific Notation? | To make it easier to work with large numbers we often express them with scientific notation using powers of ten. The exponent (power of ten) is just the number of places past the decimal point |
| What can be calculated from the Stefan Boltzman law? | If the absolute temperature and luminosity of a star are determined the the size of the star can also be calculated. This law says that the luminosity (L) of a star is proportional to the swuare of its radius (R) times the fourth power of surface temp. |
| First Stefan-Boltzman Law and Second Sefan-Boltzman law? | A star's energy is proportional to its temperature4; Luminosity: L = 4πR2σT4...R = radius of star σ = Stefan-Boltzmann constant T = surface temperature of star |
| What is Luminosity? | The total amount of light a star shines into space per second. |
| How is Luminosity measured? | Measured in units of watts (energy/time) |
| What is the sun's luminosity? | 3.85 x 10^26 watts |
| What is a visual Binary star? | Mizar in ursa Major. Can be resolved with a telescope. Albiero in Cygnus. |
| What is a Eclipsing Binary? | Changes in brightness regularly as one star blocks it's own companion. |
| What is an Optical Double Binary? | Member stars have no actual physical relationship to one another. A pair of stars that appear to be to close to each other in the sky to be viewed from Earth. Actually one is much more distant than the other. |
| What is Spectroscopic Binary? | Binary nature revealed by its spectrum. Can NOT be resolved in a telescope. A varying doppler shift is apparent in the spectral lines as the stars approach and recede from Earth. MIZER A that can NOT be resolved with a telescope. |
| What is Astrometric Binary? | Unseen companion inferred from variable proper motion of visible companion. |
| What is a binary star system? | a binary star system (two stars orbiting a mutual center of mass) is more common than our lonely star system (the Sun). |
| What does the method of Parallax measure? | used in measuring the distances to nearby stars. By observing parallax, measuring angles, and using geometry, one can determine distance. |
| What is one parsec (pc) | It is the distance to an imaginary star. |
| How do you caclulate the distance to any star from its measured parallax...what is the formula? | Stars distance in PC = 1/parallax. |
| What does the Doppler Shift tell us? | The speed with which the star is approaching us or receding (its radial velocity |
| What else can absorption lines tell us? | the star's magnetic field |
| What is it called when the object moving away, causing the line to be shifted towards the red? | Redshift. |
| What is it called when the object moving towards us causing the line to shift towards the blue? | Blueshift |
| What is the shift when a stars wavelengths are shorter? | Blueshift |
| What is the shift when a stars wavelengths are longer | Redshift |
| What is a stars energy proportional to? | It's temperature. |
| What is found using the stellar parallax? and what is the formula? | Distances D = 1/p Where P = the angle in arcseconds. D = distance in "parasecs" |
| What is the typical unit for an angle measurement? | degree |
| What is the Bohr Atomic Model? | each elements atoms have a nucleus with a unique number of positively charged protons circled by the same number of electrons bearing a corresponding negative charge. Atoms are normally electronically neutral. |
| What does inverse mean? | 1 over |
| What does 1 / R mean? | 1 over R the distance squared. |
| What is one of the most distant stars you will see with your eye alone. That’s because it’s one of the most luminous stars in the Milky Way galaxy. | Deneb. White Deneb is the 20th brightest star in the sky |
| What is more to know about Deneb? | Deneb is circumpolar as seen from locations of about 45 degrees north latitude, from the northern U.S, Deneb never sets but instead circles round the pole star. It cant be seen south of about 45 degrees south latitude |
Created by:
enduringgrace