Already the first question...

  1. njjmfm
    njjmfm
    Now since we are on the honor code, we cannot give each other answers, but I need some help.

    Part A Question 2:
    The Sun, at a distance of 149.6 million km from Earth, subtends about the same angle in the sky as does the Moon, with a radius of 1737 km at a distance of 384,400 km from Earth. Use this information to find the radius of the Sun in km. Round your answer to three significant figures.

    Would this be set up:
    .5/57.3=AB/149.6km
    I figure alpha= .5 degrees because of the moon being about half a degree in the sky.

    Part B Question 4:
    What is the maximal altitude in degrees above the horizon at which it is ever possible to find the Moon when observing at 42 degrees northern latitude? Round your answer to two significant figures.

    In the video he said that the moon can extend 5 degrees north/south of the ecliptic. Does this mean that the moon can get up to 28.5 dec and as low as -28.5 dec?

    Thanks for any assistance and good luck!
  2. Ezsharkman
    Ezsharkman
    I was just looking at this thread on the subject of ?# 2
    https://class.coursera.org/introastr...d?thread_id=11

    Gotta study what they are saying but it might help you 2 =)
  3. Ezsharkman
    Ezsharkman
    As for the moon ? You are correct about the maximum height of 28.5 degrees (23.5 degrees of tilt plus Moon's orbit tilt of 5 degrees)

    all you need to do is factor in the location of the observer .
    Think 90 deg minus the lat of observer plus maximum height of 28.5= maximal altitude in degrees =) dont forget to round it up
  4. Melissa 44th Lat NY
    Melissa 44th Lat NY
    Oh the math! I took one look at the first question and freaked! I'm definitely one of those people who experiences pain when confronted with a math problem. But onward. There is something completely worthy to learn here.
  5. Tony M
    Tony M
    I'm going to have to dust off some cobwebs in my brain - that's for sure!
  6. Star Rider
    Star Rider
    A "scientific" calculator will be a great help with the math. They are about $10 bucks or so. Make sure you get a "Scientific" calculator instead of a "normal" calculator.

    Clear Skies,
    Bob
  7. Starprober
    Starprober
    I use the calculator that is part of Windows 7.

    It has a scientific calculator mode that gives you all the functions you need.
  8. njjmfm
    njjmfm
    I needed 4 turns on each to get a 100 on each, it's pretty confusing.
  9. Myke
    Myke
    .5 isn't accurate enough to give you the right answer, so you have to use the formula twice to solve the question. You also have to convert 57.3 into arc-seconds, which was mentioned in one of the lessons as being 206,265. What I did was double the moon's radius to get it's diameter (which will be AB in the formula), then divide that by 384,400 (which is R). Multiply by 206,265 and you'll then have alpha in arc-seconds. From there you just plug alpha, 206265 and 149.6M into the small angle formula again to solve for AB (the Sun's diameter). d/2 = radius. You also have to remember not to round anything off until your final answer.
  10. jes29651
    jes29651
    I have all the correct answers except for one. Does anyone know if the Q/A will be given before the next chapter, or the end of the course ?

    Jim
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