Solar Spectra Demonstrations How do we know about the composition and motions of stars?
The Hydrogen Atom • What are atoms made of? • Nucleus & Electrons • Where are the electrons located? • In orbits around the nucleus • What are the electrons doing? • Zooming around the nucleus • What ELSE are the electrons doing? • See this simulation
Conclusions • When electrons are excited (having extra energy), they ‘jump’ to a higher energy level • When electrons lose energy, they ‘fall’ to a lower energy level by emitting a photon (light energy) • We see the photons as “spectral lines (lines of light)
Light is Energy! • Visible light is only a small part of the Electromagnetic Spectrum • Stars (and other bodies in space) emit all kinds of electromagnetic energy, most are not visible • The Electromagnetic Spectrum includes waves like: Radio, Microwaves, Ultraviolet, X-rays
Spectroscopes • Helps us see the spectral lines of a sample • There are 3 types: Continuous, Emission, and Absorption Spectrums seen here • Each element has its own distinct spectrum pattern seen here • We can match the spectral lines from the stars to known elements on Earth to find the composition of the stars (See Gizmo)
Classifying Stars • Along with what the stars are made of, we look at the star’s surface temperature to help us classify them • OBAFGKM are the different classes we use to classify the stars according to their colour and temperature • When we plot these together, we get the HR DIAGRAM (See Gizmo)
Motion of Stars • How would you tell if there’s a bee around someone far away? • How can you tell from a star’s spectral lines that it’s moving? • When the spectral lines are shifting • The motion of a star tells us what’s around it, see simulation here • The Hammer Throw Comparison