IDL Tutorial Day 2 Dt: 2 Jun 21 By: Suman Panda email: sumanpanda81@gmail.com ---------------------------------------------------------------------- The waxing and waning of sunspots has been recorded since their discovery by Galileo in the 1600s. The Solar Physics Group at NASA’s Marshall Space Flight Center provides a record of monthly sunspot numbers dating back to the year 1749. The file spot_num.txt, containing monthly averages and standard deviations of sunspot numbers, can be freely downloaded from http://solarscience.msfc.nasa.gov/greenwch/spot_num.txt. The numbers in this file are derived from the International Sunspot Numbers, compiled by the Solar Influences Data Analysis Center in Belgium. We will learn: How to read data from a text file. How to save data to a text file. How to We will make a yearly averaged sunspot plot. Multiple plots in one window