Concrete is the most common artificial composite material of all and typically consists of loose stones (aggregate) held with a matrix of cement. Concrete is a very robust material, much more robust than cement, and will not compress or shatter even under quite a large compressive force.
2) Y-axis contains absolute brightness Why do astronomers use the H-R Diagram? Astronomers use H-R Diagrams to classify stars and to understand how stars change over time.
Absolute magnitude is a measure of the inherent brightness of a celestial. object. This scale is defined as the apparent magnitude a star would. have if it were seen from a distance of 32.6 light-years. The lower the. number, the brighter the object. Negative numbers indicate extreme. brightness.