Example 1) Astronomers have measured the distance from the Sun to the nearest star (Proxima Centauri, a companion of the bright star Alpha Centauri) to be about 25 trillion (25,000,000,000,000) miles. Express this number in scientific notation.
(A) 25 x 1013, (B) 2.5 x 1013, (C) 2.5 x 1012, (D) 2.5 x 10-12, (E) 25 x 10-12.
Example 2) The luminosity of a star is defined as
(A) the wavelength at which most of the photons are emitted, (B) the amount of energy per second emitted by the object, (C) the brightness the star appears to have as we see it from Earth, (D) the distance the star would have if it was located 10 parsecs from the Earth, (E) both B and C.
Example 3) As the temperature of a blackbody emitter increases, the wavelength at which most of the photons are emitted shifts to ______________ while the overall intensity of light from the object ______________.
(A) shorter wavelengths // increases, (B) shorter wavelengths // decreases, (C) longer wavelengths // increases, (D) longer wavelengths // decreases, (E) longer wavelengths // stays constant.
Example 4) Which of the following sentences does not use the term 'angular size' or 'angular distance' correctly?
(A) The angular size of the Moon is about 1/2 degree. (B) The angular distance between those two houses in the distance is 30 degrees, (C) The angular size of the Sun is about the same as that of the Moon, (D) The angular distance between those two bright stars in the sky is about 2 meters, (E) You can use your outstretched hand to estimate angular sizes and angular distances.
Example 1) Imagine you observe the planet Jupiter through the BGSU telescope, and you measure the angular diameter of Jupiter to be 43.5 arcseconds. A staffmember at the Stargaze tells you that Jupiter was 6.78x108 km from the Earth. (a) What is the physical diameter of Jupiter? [Show your work]. (b) If you observe again one month later, when the distance between Earth and Jupiter is smaller, will its angular diameter be larger, smaller, or unchanged? [Here are a few related practice problems and answers].
Example 2) Describe how astronomers use trigonometric parallax to measure distances to stars.
The long essay question will be one of the three following questions (I will choose which!). You may prepare as much as you like in advance, but you may not refer to your notes during the exam.
Essay 1: Why is the determination of distances one of the most important astronomical pursuits? List and briefly describe as many methods as you can for determining the distances to stars, clusters of stars, galaxies, and clusters of galaxies. Disucss their relative strengths and weaknesses.
Essay 2: Describe the origin of the universe and its evolution to the present time, according to the Big Bang Theory. Looking to the future, astronomers predict that the universe will evolve in one of three possible ways. Describe each of these three possible fates. What must we observe in order to determine which fate will befall us? How well are these observable parameters measured, and which of the three fates does the current observations favor?
Essay 3: Briefly describe an atom of each of the following chemical elements: Hydrogen (1-H) , Helium (4-He), Carbon (12-C), and Iron (56-Fe). According to current astronomical study, when and where in the Universe was each of these elements created? Briefly describe how each was created. How does the total amount of each element in the universe change over the lifetime of the Universe?