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Discussion Questions
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1.5 Discussion questions
Why do ancient stargazers call planets "wandering stars"?
Does the Sun rise in the East? Same position in the East everyday? Use Stellarium to find out! On Stellarium, look to the East. Set the time to around 6:30-7:00 am to see the sunrise. Increase the date by a month repeatedly. Does the position of sunrise change over the year? Describe your observations.
It takes 365 days for Earth to complete 1 revolution (2 \pi radians) around the Sun. What is the angular speed (rad/s) and speed (m/s) of Earth in the rest frame of the Sun?
Suppose you want to reach Alpha Centauri (nearest star to us) in 100 years. How fast do we need to move? How about reaching Andromeda Galaxy (nearest galaxy to us) in 100 years?
The Moon's equatorial diameter is 3,476 km and its orbital distance from Earth varies between 356 400 km and 406 700 km. The Sun's diameter is 1390 000 km and distance from Earth ranges between 147.5 and 152.6 million km. Find the Moon's and Sun' angular size at their respective minimum and maximum distance from Earth. Discuss the implications on solar eclipses.
Suppose that the typical size of a galaxy is 100 000 light years, and typical separation between galaxies is 1 million light years. Also suppose that the typical size of a star is 1 million km, and typical separation between stars is 5 light years. Discuss the implications on stellar and galactic collisions.
Oh no! Matthew has stolen the SPS telescope again! This time around, he has brought it into the mangroves in Pulau Ubin, and is using it to observe fireflies. Assuming that he is 50m away from the fireflies, and fireflies are blinking yellow (580nm), how far apart must they be for him to discern them apart?
The SPS telescope has an aperture of 15.24cm.