Gravitational lensing.
How can one source reach us more than once?
Move foreground galaxies, see one source appear in several forms, and replay delayed flashes or a supernova.
Open gravitational lensingTHE LAST TRANSMISSION / LIGHT LAB
The light arrives.
Follow what it reveals.
A telescope receives light. Astronomy asks what happened before it reached us. Explore gravity, the structure of images, spectral fingerprints, motion, distance and the timing of a distant event through interactive, source-linked teaching models.
INTERACTIVE EXPERIMENTS
Spectroscopy.
What can missing wavelengths tell us?
Compare continuous, emission and absorption spectra. Select gases, change resolving power and inspect sodium’s close pair of lines.
Open spectroscopyParallax.
How does a moving viewpoint reveal distance?
Move Earth around the Sun, compare viewpoints six months apart, and see how a star’s apparent shift reveals geometric distance.
Open parallaxRedshift & blueshift.
What shifts a spectrum, and what does that imply?
Move a source toward or away from Earth, compare shifted spectral lines, and distinguish radial Doppler motion from temperature and distance.
Open redshift & blueshiftHOW TO READ A LIGHT LAB EXPERIMENT
Change a model.
Keep the distinction.
Each experiment separates its calculated behavior from observations of the real Universe. Change a controlled input, follow the result and read the assumptions underneath. A replay demonstrates a model; it does not repeat an astronomical observation.
Different measurements answer different questions. Parallax uses geometry. Spectroscopy identifies and compares features in light. Redshift and blueshift concern shifted wavelengths and require interpretation. Visible redness or blueness alone is not a distance measurement.
Follow the scientific inquiry guideINVESTIGATION / AN UNEXPLAINED OPTICAL RECORD
A star blinked twice.
What changed the light?
Two closely resembling disturbances appeared in HD 89389’s light, 4.4 seconds apart. Could something in the foreground have altered the arriving light?
This event has not been identified as gravitational lensing. The lensing experiment demonstrates a separate, established mechanism; it does not explain or reproduce these optical pulses. The 4.4 seconds is the separation of the recorded disturbances, not a measured delay between lensed images.