Electromagnetic Spectrum

The Universe

The Big Bang forms the universe…..The energy creates stars.Gravity pulls stars together into Galaxies.The stars vary in their lifecycle, size,

temperature, brightness, and amount of energy released.

The types of energy released by stars have a range or Electromagnetic Spectrum.

We call it Solar Energy

Electromagnetic Spectrum

We learned that energy is transferred through conduction, convection, and radiation. But in what form?

Energy takes many wave forms: radio, microwave, infrared, visible light, ultraviolet, x-ray, gamma ray.

Electromagnetic spectrum: an organized range of energy waves from low energy to high energy waves.

Electromagnetic spectrum

H-R DiagramThe H-R diagram has the hotter stars

towards the left. The brighter stars towards the top.

Now think about their color. A star’s color represents the Electromagnetic spectrum (spectra).

Stars that are Red are lower in energy and have longer wavelength.

Stars that are blue/white are higher in energy and have shorter wavelength.

Star Spectra (color)

Star Spectra (temp vs. brightness)

Apparent and Absolute magnitude

Apparent magnitude: the brightness of a star as seen from earth; what we believe is bright.

Absolute magnitude: the actual brightness of a star based on its mass and energy spectra.

Redshift: stars that are moving away from us appear to have a red color; longer spectral wavelength.

Blueshift: stars that are moving towards us appear to have a blue color; short wavelength.

Redshift & Blueshift Spectra (draw)

Electromagnetic Info

Energy waves are measured in Hertz.

Hertz: number of cycles per second (frequency).

Longer waves have low frequency and shorter waves have high frequency.

Different wavelengths help us gain information about a Star’s properties .

Any Questions?