One law.
Your turn to experiment.
Change a setting, observe what happens and understand why. The laboratory connects the book’s explanations to experiments you can control.
Why does a planet
move at
a changing speed?
Create an orbit, move the planet through time and observe its speed. The ellipse’s shape, the orbit’s size and the star’s mass become parameters to explore.
Free · No account · Use the experiment without starting an animation
Why do stars
have
different colours?
Change the temperature and explore the spectrum, its peak and the blackbody colour. Compare the ultraviolet, visible and infrared shares of radiation too.
CIE 1931 colour calculation · Data and method available
How can we read
a star’s velocity
in its light?
Shift the hydrogen lines, compare them with their rest positions and zoom in on small displacements. A fictional cycle connects the Doppler effect to the search for exoplanets.
Two reference lines · Close-up · Periodic example
Kepler’s laws.
Putting the phenomena in context.
Volume III, “Comprendre l’astrophysique”, accompanies your exploration of gravitation, light, stars and cosmology.