# doc - Jorge Arias Chapter 1 SPS 1020 Page 1 of 15 2 A...

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Jorge Arias SPS 1020 Page 1 of 15 Chapter 1 2. A theory is a hypothesis that has gone through experimental or observational tests and a law of physics is a set of physical principles with which we can understand natural phenomena and the nature of the universe. 4. Skepticism in science provides an attitude in scientific thinking that emphasizes that no fact or principle can be known with complete certainty; the tenet that all knowledge is uncertain. 11. Astronomers use arcmins, arcsecs and degrees as unit for the expression of small angles. degree (angle) 1/360 circle arcmin 1/60 degree arcsecond 1/60 arcminute 15. A couple of the advantages of power-of-ten notation are that in computation scientific notation makes adding, subtracting, multiplying and dividing numbers much simpler, also, creating and reading tables get easier with this notation. 18. For an astronomer, the advantage of using light years as a unit of distance is that they evade using huge numbers. For example, the nearest star (other than the sun) is 2.48072692 × 1013 miles away; instead, they say that Proxima Centauri, is about 4.22 light-years away which is Much simpler. 19. A parsec is a unit of length, equal to just over 30 trillion kilometers, or about 3.3 light years. The parsec is used in astronomy, and its length is defined as the distance from the sun at which two imaginary lines—one projected from the Earth, and one projected from the sun at a right angle to a third line connecting the Earth and the sun—intersect in space at an angle of 1 arc second. 1 kilo Parsec = 0.001 mega Parsecs 20. Units of measurement: a. km – kilometer b. cm – centimeter c. s – second d. km/s – kilometer per second f. m – meters g. m/s – meters per second h. h – hours i. y – yards

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Jorge Arias SPS 1020 Page 2 of 15 e. mi/h – miles per hour j. g – grams k. kg – kilograms 26. A hydrogen atom has a radius of about 5 x 10-9 cm. The radius of the observable universe is about 14 billion light years. 39. The angular size of the Orion Nebula is 65` x 60` which is the same as 1*1 degrees. On the other hand, the angular size of the moon is 0.5 degrees. Therefore, we can agree that the comparison is that the moon is half the size of the Orion Nebula. 43. The Orion Nebula is one of the brightest nebulae, and is visible to the naked eye in the night sky. It is in fact part of a much larger nebula that is known as the Orion Molecular Cloud Complex. The Orion Molecular Cloud Complex extends throughout the constellation of Orion and includes Bernad’s Loop, the Horsehead observations show that dust grains in these protoplanetary disks are growing, beginning on the path towards forming planetesimals, solid objects thought to exist in protoplanetary disks and in debris disks. Chapter 2
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## This note was uploaded on 11/03/2008 for the course ASTRO 1002 taught by Professor Oswalt during the Spring '08 term at FIT.

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doc - Jorge Arias Chapter 1 SPS 1020 Page 1 of 15 2 A...

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