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The Science 360

at Event Horizon - Science, Space and beyond

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Snapshot of the universe zoom-out simulation: distant galaxies inside a ring of the cosmic microwave background Space Interactive

Zoom out to the edge of the universe

Scale · 17 stops
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Simulations See all
Snapshot of the universe zoom-out simulation: distant galaxies inside a ring of the cosmic microwave background Space Interactive

Zoom out to the edge of the universe

Scale · 17 stops
Earth orbiting a glowing star inside a green habitable-zone ring Space Interactive

What if we replace the Sun?

Space · 9 min guide
A spinning ring-shaped space station seen from above with a tiny person on the rim and a curving ball trail Space Interactive

Spin a space station: artificial gravity

Space · 9 min guide
Mars as a rust-red disc with a thin glowing atmosphere Space Interactive

Could we terraform Mars?

Space · 8 min guide
A muon falling 15 km beside survival curves with and without relativity Physics Interactive

The muon paradox

Relativity · 9 min guide
A black hole drawn as a black disc with a glowing rim inside a dashed comparison ring Space Interactive

How small can you squeeze it?

Space · 8 min guide
A planet on an elliptical orbit around a glowing star with two shaded wedges of equal area Physics Interactive

Orbits and Kepler’s laws

Space · 7 min guide
The Milky Way drawn at true scale from the scale of the universe zoom Space Interactive

Scale of the universe

Scale · 8 min guide
Earth and Jupiter beside the Sun at true relative scale Planets Interactive

Planet and star size comparison

Size · 8 min guide
A person standing on each of six worlds from Pluto to the Sun, drawn taller where gravity is stronger Planets Interactive

Weight on other planets

Gravity · 8 min guide
A gibbous Moon beside a top-down diagram of the Sun, Earth and Moon orbit with eight phase icons Space Interactive

Moon phases: why does the Moon change shape?

Space · 8 min guide
Earth at four points on its orbit with a fixed tilted axis beside a globe split into day and night Space Interactive

Why do we have seasons?

Earth · 9 min guide
A side view of the Moon’s tilted orbit and Earth’s shadow above a total solar eclipse with its corona Space Interactive

Solar and lunar eclipse simulator

Space · 10 min guide
Earth seen from above the pole with two ocean bulges lined up with the Moon, next to a two-day tide curve Earth Interactive

How do tides work?

Earth · 8 min guide
A spacecraft on an elliptical transfer orbit from Earth to Mars beside a chart of fuel cost for every launch date Space Interactive

How long does it take to get to Mars?

Space · 9 min guide
A one-stage and a two-stage rocket with fuel gauges beside bars comparing their speed change to what orbit needs Space Interactive

Rocket equation: why is orbit so hard?

Space · 9 min guide
A glowing arc leaving a cannon beside a fainter 45 degree arc and a graph of range against launch angle Physics Interactive

Projectile motion simulator: which angle goes farthest?

Mechanics · 8 min guide
A brass pendulum bob swinging from a mount with energy bars and a phase-plane loop Physics Interactive

Pendulum period formula and simple pendulum simulator

Mechanics · 9 min guide
A square of glowing atoms, some decayed to faint rings, beside the exponential half-life curve Physics Interactive

Half-life and radioactive decay simulator

Nuclear · 9 min guide
A beam of light through two slits onto a screen with a brightness graph of bright and dark fringes Quantum Interactive

Double slit experiment: waves, particles and watching the slits

Quantum · 8 min guide
A spacetime diagram with the home twin’s straight world line and the traveller’s bent one Relativity Interactive

The twin paradox: how much younger does the traveller return?

Relativity · 9 min guide
A light ray bending as it enters water, with the reflected ray, the normal and the angle arcs Light Interactive

Snell’s law: how light bends, reflects and gets trapped

Light · 9 min guide
NE555 LED flasher on a breadboard beside an oscilloscope showing a 1.05 Hz square wave and the capacitor voltage between 3 V and 6 V Electronics Interactive

555 Timer Calculator and Astable Simulator

Electronics · 9 min guide
A 140 m asteroid impact over a made-up city: a 2.4 km crater and blast rings out to 49 km, with 150 megatons of energy Space Interactive

Asteroid impact simulator

Space · 9 min guide
A 10,000 mAh power bank charging a phone over USB, with bars showing 37 Wh in the cells, 30.3 Wh at the 5 V port and 1.4 full charges of a 5000 mAh phone Electronics Interactive

Battery Life Calculator: mAh to Hours

Electronics · 8 min guide
Earth squeezed into a black hole: an event horizon 1.77 cm wide drawn at true scale beside a 19 cm hand Space Interactive

Schwarzschild radius calculator

Space · 8 min guide
Planck blackbody curve of the Sun at 5,772 K peaking at 502 nm with the visible band in rainbow colours, a white star and a colour bar from 1,000 K to 40,000 K Stars Interactive

Blackbody radiation and star colour

Stars · 8 min guide
A pot boiling on a mountainside at Leh, 3,500 m, where water boils at 88.3 °C under 65.8 kPa of air pressure Earth Interactive

Boiling Point at Altitude Calculator for Water

Earth · 8 min guide
A steel cargo ship floating in sea water with 56 percent of its hull below the surface, beside weight and buoyant force arrows of 113 MN Physics Interactive

Buoyancy simulator

Physics · 8 min guide
RC circuit charging a 10 microfarad capacitor from 5 V through 100 kilohms, with the voltage curve marked at one to five time constants and an energy card Electronics Interactive

Capacitor Charging Simulator: RC Curve, Current, Energy

Electronics · 8 min guide
Newton's cradle simulation with five steel balls: one ball in, one ball out, with velocity bars and 100 percent of the energy left Physics Interactive

Elastic and inelastic collisions

Physics · 8 min guide
An ambulance on a city road sending out circular sound waves that bunch up ahead of it, with a pitch chart falling from 755 Hz to 652 Hz Physics Interactive

Doppler effect simulator

Physics · 8 min guide
Side view of the curved Earth: a sight line from a beach grazes the horizon at 4.99 km and hides the bottom 15.4 m of a 40 m ship 20 km away Earth Interactive

Earth Curvature Calculator: Horizon and Hidden Height

Earth · 9 min guide
Magnitude 8 against magnitude 6 earthquake: a 100 times taller seismogram and 1,000 times the energy, 15 megatons of TNT against 15 kilotons Earth Interactive

Earthquake energy calculator

Earth · 8 min guide
Electric field lines of a dipole, +2 nC and -2 nC 12 cm apart, with a test charge feeling a 2.75 kN/C field Physics Interactive

Electric field lines

Physics · 8 min guide
A two storey house cut open with two ACs, fans, a fridge and a geyser running, an electricity meter reading 515 units and a Delhi slab tariff bill of 2,498 rupees Energy Interactive

Electricity Cost Calculator: Appliance Units and Bill

Energy · 9 min guide
A blue electric SUV with a cut-away floor battery plugged into a 60 kW DC fast charger at dusk, with a charge curve that falls after the knee, for a 10 to 80 percent session of 40 minutes Energy Interactive

EV Charging Time Calculator: Home and Fast Charging

Energy · 8 min guide
Cut-away Earth with inner core, outer core and mantle, and a person falling feet first down a tunnel from Delhi, 3,665 km deep at 8.6 km/s on a 38 min 10 s crossing Earth Interactive

Fall Through the Earth Simulator: Gravity Tunnel

Earth · 10 min guide
A room in a power cut run by a 700 VA inverter and a 150 Ah tubular battery at 60 percent, with a chart showing 3 hours of backup against 3 h 39 min from the simple formula Energy Interactive

Inverter Battery Backup Calculator (VA, Ah, Hours)

Energy · 8 min guide
A bench supply at 5 volts driving a glowing red LED through a 150 ohm resistor, with the schematic and a current gauge at 20 mA Electronics Interactive

LED resistor calculator

Electronics · 8 min guide
Convex lens ray diagram with a candle between F1 and 2F1 and its enlarged, inverted real image beyond 2F2 Physics Interactive

Lens and mirror ray diagrams

Light · 9 min guide
Half adder circuit built from one XOR and one AND gate adding 1 + 1 to give 10 in binary, with its truth table Electronics Interactive

Logic Gate Simulator with Live Truth Tables

Electronics · 9 min guide
A 220 V supply lights a 1200 ohm bulb on a workbench with an ammeter reading 183 mA and a voltmeter reading 220 V, beside the Ohm's law triangle and power wheel Electronics Interactive

Ohm's law calculator

Electronics · 8 min guide
Microcontroller PWM pin at 50 percent duty and 490 Hz driving an LED and a fan motor, beside a scope showing the 5 V square wave and 2.50 V average Electronics Interactive

PWM Duty Cycle Simulator: Waveform and Average Volts

Electronics · 8 min guide
A 4.7 kilohm resistor with yellow, violet, red and gold bands on a workbench mat, each band labelled with its digit, multiplier or tolerance Electronics Interactive

Resistor color code calculator

Electronics · 8 min guide
Three 60 W bulbs wired in parallel to a 230 V switchboard, each drawing 261 mA, with the circuit diagram below Electronics Interactive

Series and parallel circuits

Electronics · 8 min guide
Simulated sunset over mountains with an orange red Sun on the horizon at air mass 31 and an orange glow fading to blue grey overhead Earth Interactive

Why is the sky blue? Sky and sunset simulator

Earth · 9 min guide
Solar panel tilt diagram for Delhi in December: the low winter Sun path, a rooftop panel tilted at 52 degrees receiving 915 W/m², and a monthly energy chart against the best fixed tilt of 26 degrees Energy Interactive

Solar Panel Tilt Angle Calculator by Location

Energy · 9 min guide
A belly-down skydiver falling past clouds beside a speed-time graph that levels off near 55 m/s Physics Interactive

Terminal velocity calculator

Physics · 9 min guide
Arduino pin driving a PN2222A through a 560 ohm base resistor to switch a 5 V relay and lamp, with the schematic and collector current chart Electronics Interactive

Transistor as a Switch: Base Resistor Calculator

Electronics · 9 min guide
Voltage divider loading effect: a 10 kilohm load on a 10 kilohm and 20 kilohm divider pulls the output from 3.33 V down to 2.00 V, shown on the output voltage against load resistance curve Electronics Interactive

Voltage Divider Calculator with Load Effect

Electronics · 8 min guide
A 12 V solar panel feeding a charge controller through 10 metres of 4 mm² copper cable, the voltage falling from 12.00 V to 11.14 V along the run, with a chart of drop for each wire size against the 3 percent limit Electronics Interactive

Voltage Drop Calculator: Wire Size, Length and Amps

Electronics · 8 min guide
A moon approaching a planet, with a dashed Roche-limit circle and a band of debris Space Interactive

Roche limit simulator: turn a moon into rings

Space · Guided experiments
Five Lagrange points around two bodies with a spacecraft trail in the rotating frame Space Interactive

Lagrange points simulator: L1 to L5

Space · Guided experiments
Earth overtaking Mars beside a graph of the planet’s apparent sky longitude Space Interactive

Retrograde motion simulator: Mars and Mercury

Space · Guided experiments
A spacecraft bending around Jupiter beside incoming and outgoing velocity vectors Space Interactive

Gravity assist simulator: a Jupiter flyby

Space · Guided experiments
A gas speed distribution crossing an escape-speed marker above a planet Space Interactive

Atmospheric escape simulator: can a planet keep its gas?

Space · Guided experiments
Two clocks with different rates beside the horizon of a nonrotating black hole Relativity Interactive

Gravitational time dilation simulator: black hole clocks

Relativity · Guided experiments
Rest and observed hydrogen spectral lines shifting along a wavelength ruler Space Interactive

Redshift and blueshift simulator: spectral detective

Space · Guided experiments
A planet crossing its star above a live dip in the star’s brightness Space Interactive

Exoplanet transit simulator and light curve

Space · Guided experiments
A star beside an H–R diagram with an evolution track from the main sequence to a remnant Space Interactive

Star life cycle simulator and H–R diagram

Space · Guided experiments
Two orbital paths with repeated conjunction directions marked around a central star Space Interactive

Orbital resonance simulator: repeating planetary rhythms

Space · Guided experiments
Physics Coming soon

How body shape changes lift

Physics

Featured
Space № 01

500 Rule vs NPF Rule: Which Is Right for Sharp Stars?

Why the 500 rule gives trailed stars on modern cameras, how the NPF rule works out the longest exposure from pixel size and aperture, and worked examples for full frame, APS-C and phones.

13 min read
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