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.
1 Magma is molten rock that flows beneath the earth's surface. 2  Igneous rocks are formed by cooling magma. 3  The location of the formation of the rock, as well as how fast the magma cools will determine the type of igneous rock. 4  Intrusive rocks form from the cooling of magma deep beneath the earths surface. Igneous rocks that form too quickly for crystals to form have what is called a glassy texture. 2  Obsidian is the only glassy igneous rock, and can be identified by its dark color. 3  This looks like dark black glass.