Life Cycle of a Star and the formation of the elements:
Life Cycle of a Star animation with written explanations for each stage in the life cycle of a star
H-R Diagram animation (for started on 4/25)
Mastery Check Review (PDF) (Keynote) includes H-R Diagram practice, Life Cycle of a Star images and questions, and review of fusion.

Hubble Article

Classifying Galaxies link (use this to complete the "Classifying Galaxies!" activity in class on 4/29)
Galaxies Galore - more about galaxies and games
Even more about galaxies

Cepheid Variables
Link to pictures of cepheid variable in the galaxy M101
Link to animation of cepheid variable in the galaxy M101
More information about Cepheid Variables
Even more about Cepheid Variables
How do cepheid variables help determine distance?

Pictures from Hubble Space Telescope

Hubble's Law Balloon analogy
Until this point, we have been describing the redshift of light as a Doppler shift. However, now that we understand the Universe to be expanding, we need to revise this description. The way we understand the cosmological redshift of galaxies is as follows. Picture a photon emitted by a distant galaxy towards the Earth. That photon has a specific wavelength. However, during the trip between the distant galaxy and Earth, the space between that galaxy and Earth has expanded. The expansion of space causes the wavelength of the photon to stretch, so when it arrives at Earth, it has a longer wavelength than when it left. Mathematically, this behaves exactly as if the photon was Doppler shifted. So we interpret the galaxies as moving through space away from us. However, the proper interpretation is that the galaxies are at specific positions in space, and the space between them is expanding. An animation illustrating the cosmological redshift using the balloon analogy for the expansion of space is below.
Link to the Balloon animation for the analogy

Cosmic Microwave Background Radiation
Link to web quest for Wednesday 5/6
Video Link