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.
If the cooling of the lava happened more slowly, the rocks would be fine-grained or porphyritic â where the crystals differ in size, with at least one group of crystals obviously larger than another group. Basalt is a common form of extrusive igneous rock and forms lava flows, lava sheets and lava plateaus.