astronomy HW1

# astronomy HW1 - 2 emitted by a typical person this way c...

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Astronomy 1F03 Problem Set 1 Due Date: Wednesday Sept 28th, 2011 1. An asteroid has a perihelion (closest to the Sun) distance of 2.0 AU and an aphelion (furthest) distance of 5.0 AU. Calculate its orbital semi-major axis, eccentricity and period. 2. Jupiter’s moon Io has an orbit around Jupiter with a radius of 420,000 km and takes a period of 1.8 days to complete an orbit. a) If Jupiter’s moon Europa has an orbit with a radius of 670,000 km, estimate how long Europa should take to orbit Jupiter. Clearly state any assumptions you make. b) Can Europa’s orbital period be estimated (part a) without knowing the mass of Jupiter? Explain your answer. 3. Normal human body temperature peaks around 37 degrees celsius. a) Ignoring any reFected light and assuming the person is a perfect blackbody emitter, what is the peak wavelength emitted by a person at this temperature? b) What is the ±lux (energy per unit body area per unit time, in Watts per m
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Unformatted text preview: 2 ) emitted by a typical person this way? c) What is the total energy (energy per unit time, in Watts) emitted by a typical person this way? 4. You detect a spacecraft moving around a distant planet. You are located in the plane of the orbit (edge on to the orbit). You observe that the spacecraft’s radio signal smoothly varies in wavelength between 2.9995 m and 3.0005 m and back over a period of 100 minutes. a) Assume that the radio is broadcasting normally, at a constant wavelength of 3.0000 m. Describe precisely what the spacecraft is doing when the wavelength is 2.9995 m and when it is 3.0005 m. b) Since the variation is regular you can infer that the orbit is circular. Determine the radius of the orbit. c) ±rom the above information calculate the mass of the planet....
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