That is, if you observe the spectrum of a star and can determine the wavelength where the emission peaks (Î»max), you can calculate that starâs temperature. Here is another copy of the plot that we studied in Lesson 3: Figure 4.1: Two-dimensional plot of the spectrum of a blackbody with different temperatures.
Igneous rocks usually contain the most crystals. The longer it takes the magma to cool, the larger the crystals.
â¢ Intrusive rocks are made up of enormous crystals whereas extrusive rocks have tiny crystals that can be seen only with a microscope. â¢ Granite is the best example of intrusive rocks whereas the basalt is a fine example of extrusive rocks. Images Courtesy: 1  Basalt by Zureks (CC BY-SA 3.0).