Introduction to Astronomy

HW0801006

due in one week

1.          (a) The diameter of the Sun is 1.4 x 10¹¹ cm and the distance to the nearest star, Proxima Centauri, is 4.2 ly.  Suppose you want to build an exact scale model of the Sun and Proxima Centauri, and you are using a ball 30 cm in diameter to represent the Sun.  In your scale model, how far away would Proxima Centauri be from the Sun?  Give your answer in kilometers.  (b) A person with good vision can see details that subtend an angle of as small as 1 arcminute.  If two dark lines on an eye chart are 2 mm apart, how far can such a person be from the chart and still be able to tell that there are two distinct lines?  Give your answer in meters. (c) On April 18, 2006, the planet Venus was a distance of 0.869 AU from the Earth.  The diameter of Venus is 12,194 km.  What was the angular size of Venus as seen from Earth on that day?  Give your answer in arcminutes.

2.          What is the sidereal time when the vernal equinox rises?  On what date is the sidereal time nearly equal to the solar time?  Explain your reasoning.

3.          Read the essay by James Randi at the end of Chapter 2 of Universe.  In 2-3 paragraphs, describe his points of view about astrology.  In another paragraph, describe yours.

4.          There are many night sky simulator software packages on the market, including the one included in your textbook.  We mentioned Stellarium in the class, which is free of charge and has magnificent graphical interface.  To download a copy, you can visit http://www.stellarium.org/, or if you need a Chinese enhancement kit, go to http://timc.idv.tw/stellarium/.  Play around such a simulator of your preference.  Find where Jupiter is lately.  What are other bright stars near Jupiter?  Print out a copy of the screen that shows those stars and Jupiter on 10 October 2008.  What is the phase of the Moon on that evening?

5.          (Check out Question 2.38 in Universe.  It is enlightening.)