CCNY PHYS 45400 Sp 2026

Homework 1

Due: Feb 18th

Get and Plot some data!

1. Sun Tower

   Imagine you're standing in a field in Egypt, just outside of Cairo, looking due south. There's nothing around except a large tower located 100 meters right in front of you. It's 40 meters tall and 10 meters wide. It's Feb 4rd 2026, at noon in Cairo.

   Prepare a plot that shows the entire azimuthal range of your view on the horizontal axis, and 0-90 degree elevation on the vertical axis.

   1. Plot the position of the sun, as well as a rectangle that shows the tower.
   2. How high would the tower have to be (in meters) in order to block out the sun from your perspective?
   3. Also prepare two plots that show the position of the sun everyday at Noon for the year of 2026. Do one in Alt/Az coordinates and one in RA/Dec (Equatorial Coords).



2. 1610 was an exciting year

   Look up the positions of Jupiter's 4 major moons at the time when Galileo observed them and compare them to his original drawings in the Sidereus Nuncius. I'll assign everyone a day at random and try to reproduce it using the historical data from the ephemeris tables. Include the original drawing and your plot in the submission. Comment on your comparison. Are they similar? Any differences?

   Text of Siderius Nuncius: Starry Messenger

   The year was 1610, and the dates are indicated in the text.

   Some tips

   • Galileo did the experiments in Padua Italy. The latitude/longitude there is: 45.4064° N, 11.8768° E
   • When he says in the 6th hour, that means the sixth hour after sunset (which was probably around 5pm but you will need to looks that up and explain how you did it.)
   • His drawings are in the azimuthal/elevation system
   • All the objects should occupy a very small portion of the total sky - meaning the range of the axis in your plots should be quite small (< 1 degree for sure.)



3. Moon

   Go outside and take a picture of the moon (day or night). Then use Stellarium to generate a simulated view of the sky at the exact time and place of your picture. Convince yourself that the two views (observation and simulation) are in agreement. Consider both the phase of the moon, and its location in the sky.

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For all

• Include your sources and a table of the raw data you used. (This ideally would be a link to your data file online somewhere, like a github repository or google drive link. Make sure sharing is set properly so that with a single click, it can be viewed.)
• Possible source data can be found at JPL Horizons or you can find other ephemeris sources for the solar system if you search.
• Make sure all plots are formatted nicely and have labeled axes.

Due Date: Wednesday Feb 18, start of class. (via brightspace.)

Prepare your work in a typed (no handwritten math or drawn diagrams), document (pdf) with plots and any citations for any references you used, and links to any extensive code you wrote that was used.

If you used any AI to help with code or any other part of this work you must cite that and include the exact prompts. Under no circumstances do I want to read any AI generated text though.