Observatory
The Observatory
A small observatory you can walk through, one instrument per room. None of them shows a picture: each one works out its subject in your browser from a single line of physics, and moves. They hang together. Light tells us what is out there; gravity bends it, slows clocks and stretches things; stars make the elements and end as the strangest objects of all. Start anywhere; the brass rail at the top takes you on. Every room is a live instrument: drag, slide, click and listen; a brass tab on each one says where to start.
Outside
the orreryThe solar system, liveEvery planet and the big moons where they are now, with a time machine and an eyepiece on Jupiter.
the wanderersMorning star, evening starWhy Venus and Mercury never stray far from the Sun, how planets wander through the stars, and the next bright pairings.
the sundialSun time and clock timeA brass heliochronometer under the real Sun over Eindhoven, and why noon here is never at twelve.
Light · how we know
the double slitWave and particlePhotons arriving one at a time, and the pattern only waves can make.
the sirenThe Doppler effectA passing siren, the waves squeezed in front and stretched behind; then light, blue to red, and near light speed.
the spectroscopeRedshiftA star's barcode of dark lines, shifted by motion, gravity or expanding space.
the tableWhere your atoms come fromThe periodic table by origin: the Big Bang, stars, supernovae, colliding neutron stars.
Space, time and gravity
the speed limitWhy mass cannot reach cE² = (pc)² + (mc²)², the race with neutrinos and gravitational waves, and the loophole: space itself can grow faster.
the clockTime dilationA clock near a black hole and a clock on a fast train, and why GPS needs both.
the tideThe tideThe Moon stretching the Earth, live: two bulges, spring and neap, the tide at any place.
the lensThe horizonA black hole ray traced photon by photon: the shadow, the ring, the disk bent over the top.
the fallSpaghettificationTorn apart before the event horizon or after it: the answer depends on the mass, the wrong way round.
the chirpGravitational wavesTwo black holes spiralling together, seen and heard, with the real detections.
Stars · from birth to the end
the SunOur star, nowToday's Sun live in five kinds of light, its wind reaching Earth, the spot cycle since 1749, and a photon's long way out.
the life of a starStellar evolutionPick a mass and watch a star live and die over billions of years.
the lighthouseNeutron stars and pulsarsA city-sized star spinning hundreds of times a second, its beams sweeping past us; listen to real ones.
the engineActive galactic nucleiSupermassive black holes that outshine their galaxies, seen as quasars, blazars and radio galaxies.
the wobbleFinding exoplanetsThe dip in a star's light and the wobble in its lines.