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.
The morning âstarâ is a magnitude â4.7 beacon that you can spot even after sunrise. In telescopes, Venus presents a waxing crescent spanning 45 arc seconds. Thatâs more than 10 times the current apparent diameter of Mars, which is probably why you havenât looked at it for months!