Calcium is a chemical element with the symbol Ca and atomic number 20.

The California Institute of Technology (Caltech) is a private research university located in Pasadena, California.

The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their corresponding wavelengths and energies.

The U.

Princeton University is a private Ivy League research university located in Princeton, New Jersey.

Stanford University is a renowned private research university located in Stanford, California.

The Sun is the star at the center of the Solar System, and it is by far the most important source of energy for life on Earth.

A telescope is an optical instrument designed to magnify and focus light for observation of distant objects.