• Light as a wave: Has a wavelength and frequency (inversely related) and constant speed c
• Blackbody radiation: All dense objects emit continuous spectrum of radiation
• Wein's law: Hotter temperature corresponds to shorter peak wavelength (bluer color)
• Stefan-Boltzmann law: Hotter temperature corresponds to greater intensity (per unit surface area) of radiation

• Wavelength: Distance between peaks
• Frequency: Rate at which peaks pass; high frequency goes with short wavelength
• Kelvin: Temperature scale that has zero point at absolute zero (-273 degrees Celsius)

Newly released images reveal huge cliffs scaling 15,000 feet and large cracks spanning widely across Mercury's exterior.

NASA scientists believe that the tiny planet's inner, iron-rich core is cooling down and solidifying. As this process occurs Mercury is contracting in on itself, causing its outside shell to crack and buckle.