Exam 1 Terms and Questions

Exam 1 Terms and Questions - ASTR101 Defined Terms and...

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ASTR101 Defined Terms and Answered Questions from Lecture Summaries Lecture Summary 1 Astronomy: Planet: Satellite: Solar System: Star: Galaxy: collection of stars, gas and dust held together by gravity (our milky way galaxy contains about 400 billion stars) Light year: distance light travels in one year – 6 trillion miles Universe: galaxies distributed in clusters together held by gravity (about 100 billion) Science: the body of human knowledge collected and scrutinized using the scientific method Scientific method: observe, ask a question, make a hypothesis, test hypothesis, discard or revise Hypothesis: educated guess that is in the process of being tested using the scientific method Theory: develops one or more well-test hypotheses to describe many phenomena and make accurate predictions Laws of nature: observable universe is the result of physical processes; knowable through scientific experimentation and observation; laws of nature are universal Zenith: point directly overhead Nadir: point directly below Altitude: how far above horizon (angular measurement) Horizon: separates what we can see from what’s blocked by Earth, 180 degrees visible NCP: extension of NP to sky SCP: extension of SP to sky Celestial equator: extension of all points on equator to sky Circumpolar star: a star that’s 24 hour path always stays above the horizon Non-circumpolar star: 24 hour path of star crosses horizon Questions: 1. A light year is the distance light travels in one year 2. Science is the body of human knowledge collected and scrutinized using the scientific method 3. An observer at the North pole only sees circumpolar stars because these stars are above the horizon 4. The way the sky looks at the NP as opposed to the way the sky looks at the equator is that at the equator non-circumpolar stars are seen in the sky and at the NP there are circumpolar stars
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5. You can use latitude to draw a celestial sphere representation for 39 degrees N by using this information to adjust where the NCP and SCP (and the NP and SP) would be found Lecture Summary 2 Ecliptic: the path the sun takes through the stars in one orbit – not in line with Earth because Earth is titled 23.5 degrees above or below Solstices: Summer solstice is the point on the celestial sphere where the ecliptic is farthest north of the celestial equator and the moment in time when the Sun appears at that point each year (around June 21); the Winter solstice is the point on the celestial sphere where the ecliptic is farthest south of the celestial equator and the moment in time when the Sun appears at that point each year (around December 21) Equinoxes: Fall equinox is the point in Virgo on the celestial sphere where the ecliptic crosses the celestial equator and the moment in time when the Sun appears at that point each year (around September 21); Spring equinox is the point in Pisces on the celestial sphere where the ecliptic crosses the celestial equator
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This note was uploaded on 02/01/2011 for the course ASTR 101 taught by Professor Deming during the Spring '07 term at Maryland.

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Exam 1 Terms and Questions - ASTR101 Defined Terms and...

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