LEARN BY BUILDING · AGES 14–18
Five short experiments about how astronomers read the sky, see radio light and build a telescope as wide as a planet.
GAME 00 · HOW TO READ THE SKY IMAGE
FROM DIRECTIONS TO PIXELS
Each pixel covers a known angle on the sky. Across a small part of the image, astronomers use that angle per pixel to measure angular separation.
GAME 03 · ANGULAR RESOLUTION
POWERFUL RADIO GALAXY
Cygnus A is about 750 million light-years away. Its two radio lobes are giant magnetised bubbles, together stretching several hundred thousand light-years across.
GAME 01 · MULTIWAVELENGTH ASTRONOMY
Every panel shows the same Crab Nebula, but not the same information. Each wavelength traces different particles, materials and physical processes; astronomers combine them to build a fuller picture.
Images: Radio — VLA/NRAO/AUI/NSF · Infrared — NASA/Spitzer/JPL-Caltech · Visible — NASA, ESA & Hubble/STScI · UV — XMM-Newton/ESA · X-ray — NASA/Chandra/CXC. Via NASA SVS 30944.
GAME 02 · FROM GAS TO RADIO LOBES
The black hole does not blow out the lobes itself. Gas and magnetic fields outside it help make two jets. The jets carry energy far away and inflate two enormous radio-bright bubbles.
Science references: NASA: Active Galactic Nuclei · NRAO: Radio Galaxies.
GAME 04 · RADIO INTERFEROMETRY
Each pair of antennas measures one complex visibility at a location in u–v space. Add antennas to make more pairs, then let Earth rotate to sample new locations.
One antenna pair makes one visibility measurement at this moment.
This is a schematic u–v plane, not a map of positions on the sky. Each location describes a spatial pattern the array can measure. The plotted positions and Earth-rotation steps are illustrative; real coordinates depend on wavelength, source direction and projected antenna separation.Make pairs. N antennas form N(N−1)/2 distinct pairs; each pair can measure a visibility.
Choose scales. Short projected baselines sample lower spatial frequencies; long ones sample higher frequencies.
Observe over time. As Earth rotates, projected baselines change and the same pairs sample more u–v locations.
Science references: ALMA/NRAO: interferometry basics · NRAO: u–v sampling.
THE BIG PICTURE · FIVE GAMES
Each game adds one piece of the same story: a sky angle, a wavelength, a physical source, a resolution limit and an imaging method.
A scale bar turns distances in a picture into angles on the sky. Degrees, arcminutes and arcseconds are angle units.
Radio, infrared, visible, ultraviolet and X-ray images trace different particles, materials and processes. No single band tells the whole story.
Gas and magnetic fields outside a black hole help launch opposite jets. The jets make terminal hotspots and inflate radio lobes.
Angular resolution is approximately θ ≈ λ/D, with θ in radians. Shorter wavelength or larger aperture can distinguish finer detail.
Antenna pairs sample the u–v plane at locations set by their projected separations. More pairs and Earth rotation give more measured locations.
