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ASTR 101: Exam 1 SDSU with Fitzgerald | Questions with Correct Answers |
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Constellations - Recognizable patterns of stars in the sky (big dipper, orions belt) Makes locating stars easier. The official borders were set in 1928 by the International Astronomical Union (IAU). How many constellations are there? - 88 Celestial sphere - our view of the night sky; an artificial sky map created by astronomers that applied a coordinate system to it, analogous to the coordinate system of north-south latitude and east-west longitude used to navigate on the Earth. This Earth-based view of the heavens is made by pretending that the stars are attached to the inside of an enormous hollow shell, the celestial sphere, with the Earth at its center. Celestial equator - we obtain the celestial equator, which divides the sky into northern and southern hemispheres, just as the Earth's equator divides the Earth into two hemispheres. Ecliptic - sun's path North/south celestial pole - We can also imagine projecting the Earth's North Pole and South Pole out into space along the Earth's axis of rotation. Sidereal day - Star reference 23 hours and 56 minutes Solar day - Sun reference 24 hours
Difference between solar and sidereal day? - Your favorite star will rise 4 minutes earlier each successive night. How long does it take the Earth to rotate (in hours)? - 24 hours How long does it take the Earth to revolve (in decimal days)? - 365.25 days How long does it take the Earth to precess (in years)? - 26,000 years. What causes seasons? - Earths rotation on its axis which is 23.5 degrees Equinox - where the ecliptic intersects the celestial equator Solsitice - where the ecliptic is farthest from the celestial equator Summer Solstice - June 21st Winter Solstice - December 21st Fall Equinox - September 21st Spring Equinox - March 21st Longest day of the year - June 21st (beginning of summer)
3)annular (moon is closer to the sun, get a ring) Three types of lunar eclipses - 1)total
- partial 3)penumbral (lightest part of the shadow) What was Aristotle's idea for the universe? Why was he wrong? - He was responsible for the geocentric model of the universe. Had sphere of fire, earth not at center, moon/sun not the same size What was Ptolemy's idea for the geocentric model? How did he try to explain retrograde motion? Why was he incorrect? - Earth-centered, with planets moving in epicycles around the earth. He explained this by adding epicycles, very complicated motion could be explained. It was incorrect because he assumed that all planets had circular motions. What was Eratosthenes' contribution to astronomy? - He measured the earths radius about 23,000 years ago. And he noticed that when the sun was directly overhead in Syene (Egypt) it was at an angle in Alexandria on summer solstice. (1% off) What were Aristarchus' contributions to astronomy? - He obtained distances to the sun and moon. First to have idea about heliocentric universe What was Copernicus' idea for the Universe? How did he explain retrograde motion? - He produced the first comprehensive mathematical heliocentric model. He explained retrograde motion in the projection effect, found distances of planets from the sun.
Earth is in the fast lane of Mars. Why was part of the Copernican idea wrong? - He was partly wrong because he assumed all planets had circular orbits. What was Tycho Brahe's contribution to astronomy? - Made accurate observations of planets, a comet, and a supernova all without a telescope. (had a brass nose) Direct (eastward) motion - Planets move slowly to the left (eastward) relatively to the background stars. Retrograde (westward) motion - planets stop and then back up for several weeks or months. Inner planet configurations - Inferior conjunction Superior conjunction Elongation Inferior conjunction - closest Mercury/Venus can get to the Earth Superior conjunction - Farthest away Mercury/Venus can be from Earth Elongation - greatest separation among the Sun, Earth, and Mercury/Venus What is the best configuration to observe the inner planets? - Elongation
Thomas Young - Wave theory=double-slit experiment Einstein - Wave-particle theory=light as a wave experiment Wavelength - λ Wavelength - distance from crest to crest Frequency - v (nu) Frequency - the number of times per second a crest passes a fixed point Velocity (speed) - c Speed of light - c= v X λ Know the different types of radiation/light on the electromagnetic spectrum and the energies/wavelengths/frequencies associated with each type of radiation (i.e. know that gamma rays are more energetic than x-rays) - Gamma rays, x-rays, ultraviolet rays, visible light, infrared radiation, microwaves, radio waves. Violet=most energetic Red=least energetic What types of radiation make it through to the Earth's surface (transparent)? - visible light, some infrared, some UV, and radio
What doesn't (opaque)? - most UV, most infrared, all x-rays, and all gamma rays. What was Romer's discovery and why was it important? Why was he wrong? - Times for light to travel the distance between Earth and Jupiter vary as the configuration varies. He was wrong because he did not have an accurate AU value (he was 25% off) What are the 2 main types of telescopes - Refractor Reflector What is chromatic aberration? - all colors do not come to the same focal point. What type of telescope can suffer from chromatic aberration? - Refractor telescopes Name 4 Types of Reflectors - prime focus 9if you want a bright image) cassegrain focus newtonian focus coude focus (best for detail) How does the atmosphere as well as man made light (light pollution) make observing difficult? - man-made light (light polution) makes night sky brighter via reflection by atmosphere. What do astronomers do to combat difficulties in observation caused by the atmosphere and light pollution? - Earth's atmosphere absorbs most types of light. Only visible, radio, and certain IR and UV light make it through to the ground. Radio telescopes are similar to reflectors because they work similar to optical reflecting telescopes.
What is the Wien's Law formula? - lambda max= wavelength of max emission of the object (in meters). T= temperature of the object (in kelvins). Temperature can be determined by wavelength/ color (red=cooler, blue=hotter) λmax=0.0029 K m/ T What is the Stefan-Boltzmann Law? - F= energy flow = SB constant T=temperature The higher the temperature, the higher the intensity of light (brighter) F= σT^ What are Kirchoff's laws of the spectra? - 1.) A solid, liquid or a hot and dense gas alone produces a (continuous spectrum). 2.) Electrons "falling" from high energy levels to low ones emit photons and produces an emission line spectrum or abrupt spikes in brightness (Hot, low density gas). 3.) Electrons "jumping" from low levels to high levels by absorbing photons produces an absorption line spectrum or wavelengths where there is little light (cool gas in front of hot and dense gas- gas cloud absorbs some light from a star). Electron - surrounded by lighter particles called _____. Proton - Atoms consist of heavy particles (____ and neutrons) in the nucleus Neutron - Atoms consist of heavy particles (protons and ____) in the nucleus In modern astronomy, the constellations are... - 88 non overlapping sky regions, covering the whole sky
Precession is... - a very slow coning motion like a top of the Earth's axis of rotation Summertime in the northern hemisphere is when... - sunlight falls more directly on this hemisphere, heating it more than average. The most easily observed motions in the night sky are produced by... - the rotation of the Earth on its axis. The Sun's apparent path across our sky against the background starts is known as... - the ecliptic. The contribution of Copernicus to the development of astronomy was a mathematical model for... - a heliocentric cosmology in which the planets move in circular orbits. When Mercury is farthest from the Earth, it is at... - superior conjunction. Where is a planet when it is moving most rapidly in its orbit? - At perihelion According to Aristotle, our universe is... - Earth-centered, with the planets, the Sun, and the stars mounted on crystal spheres. The term "planet" actually comes from a Greek term that means... - wanderer. Would a planet that is further or closer move around the sun in shorter time? - Closer, according to Kepler's Third Law Does a planet's mass affect its orbital period? - A planet's mass does affect its orbit.
A typical refracting telescope is made up of.... - a long-focal-length lens at the front and short-focal-length at the rear (next to your eye as you look through the telescope). Violet light has a _____ wavelength than red light. - Shorter Gamma rays travel through space at what speed? - Speed of light (3 x 10^5 km/s) Theory of relativity: Einstein - The velocity of light is vacuum is constant for all wavelengths, regardless of the relative velocities of the observer and the light source. Photons of a higher energy - have higher frequencies and shorter wavelengths Light as a particle - E= h x v h=plank constant Refractor - Focuses light using lenses. bends light, and used for amateur astronomy. Reflector - focuses light using mirrors. professional astronomy. Moon's rotation period = - Moon's orbital period Interferometry - many smaller dishes linked together Most objects in the universe are - redshifting (moving away from us)
Kelvin starts at - 0 degrees Sun has explosions (solar flares) - that's why you get reality curves All light travels at the - Same Speed Angular Resolution - clarity/ detail smallest angle you can resolve two objects Magnification - bigger the lens, longer the focal length Light Gathering Power - small lens--> dimmer image/ less detail bigger lens--> brighter image/ more detail What phase do we never see of Venus? - Full, b/c sun is blocking it 1 AU - average Sun to Earth distance 93 million miles Lunar eclipses - Earth is casting a shadow on the Moon Solar eclipses - Moon is casting a shadow down to Earth
