Use stellar spectra, the Hertzsprung–Russell diagram, parallax, telescopes and galaxy measurements to explore how astronomers infer properties of distant objects. Connect observations with physical models, then compare stellar evolution, cosmic expansion and exoplanet signals.
What you can investigate
- How temperature changes a star's colour, black-body curve and peak wavelength
- How stars are classified on the Hertzsprung–Russell diagram
- How initial stellar mass changes a life cycle, with inspectable core and shell burning
- How parallax is used to determine stellar distance
- How aperture and wavelength determine telescope resolution
- How redshift, recession speed and distance are linked by Hubble's law
- How flux and magnitudes give distances using standard candles
- How cosmic expansion stretches light and cools the microwave background
- How a planet produces a transit light curve and a stellar radial-velocity signal
How does parallax reveal a star’s distance?
- Open the parallax workspace and observe the same star at two epochs six months apart. Capture its angular position against the background at each epoch.
- Find the total change in angular position. For these opposite observations, the parallax angle is half that change.
- Convert parallax in arcseconds to distance in parsecs using d = 1/p. Repeat for a more distant star and compare the angular shift.
A more distant star has a smaller parallax angle. Doubling distance halves parallax, so the same angular measurement resolution produces a larger proportional distance uncertainty for a more distant star.
Interpreting the model
The stars, galaxy survey and evolutionary sequences are teaching models. Not every workspace is required by every course; use the course guidance inside the lab to distinguish core content from enrichment. A few seconds of stellar playback do not represent a star’s physical lifetime.
Revision and practice