How Bright Is the Sun on Each Planet?

Compare Sunlight Intensity Across the Solar System

Choose a planet or adjust the distance to discover how sunlight changes across the solar system. The Earth comparison stays fixed at 1 AU. Pluto is included as a dwarf planet alongside the eight planets. Select a world marker on the graph to explore the same calculation.

Sunlight Intensity on Every Planet — Comparison Table

These values use exactly the same stored distances and inverse-square calculation as the simulator. Displayed distances are rounded to three decimal places; calculations retain the underlying precision. Follow a planet link for its explanation.

A semimajor axis describes orbital size; it is often called an average orbital distance in introductory comparisons. It is neither today’s distance nor an exact time-average distance. Irradiance calculated at that distance is also not an orbit-averaged energy flux. Explore current calculated planet positions to see why distance changes.

How Bright Is the Sun on Mercury?

At Mercury’s 0.387 AU reference distance, solar irradiance is about 9,082.67 W/m², or 667.35% of Earth’s sunlight. That is 6.67 times as much incoming solar energy per square meter, before accounting for the angle of a receiving surface.

Mercury is the closest planet, but its elliptical orbit makes the comparison especially variable. Using the shared JPL orbital elements, the model gives roughly 14,400 W/m² near perihelion and 6,250 W/m² near aphelion. Those are reference estimates, not live readings. Try 0.31 and 0.47 AU to see the large swing.

Its very tenuous exosphere provides little atmospheric filtering compared with Earth. Even so, sunlight reaches only the day side, and sloping terrain changes the energy intercepted by each square meter.

How Bright Is the Sun on Venus?

At Venus’s 0.723 AU reference distance, sunlight intensity above the atmosphere is about 2,601.23 W/m², or 191.13% of Earth’s reference. The planet receives about 1.91 times as much incident solar energy because it orbits closer to the Sun.

That figure does not describe direct sunlight on the ground. Venus’s dense atmosphere and persistent clouds scatter, absorb, and reflect radiation before it reaches the surface. A clear-space detector and a surface instrument would therefore measure different conditions.

Venus also illustrates why sunlight alone cannot predict temperature. Its strong greenhouse effect traps heat; distance is only one part of the energy balance. See NASA’s Venus overview for the atmospheric context.

How Bright Is the Sun on Earth?

Earth is defined here as 1,361.00 W/m² at exactly 1 AU, or 100.00%. This is a rounded reference for total solar irradiance: incoming electromagnetic energy across the solar spectrum, not just visible light.

The traditional term “solar constant” is useful but imperfect. Solar output varies slightly, and Earth’s real orbital distance changes during the year. NASA’s space-based irradiance measurements support approximately 1,361 W/m² as a practical nominal baseline.

This is not a typical ground-level reading. Clouds, atmospheric absorption, solar elevation, and panel orientation all matter. Averaging the intercepted sunlight across an entire spherical planet introduces a factor of four, giving about 340 W/m² before reflection. That global average answers a different question from this tool.

How Bright Is the Sun on Mars?

Sunlight intensity on Mars is about 586.21 W/m² at the 1.524 AU reference distance, or 43.07% of Earth’s sunlight. That is roughly 57% less incoming solar energy per square meter than at 1 AU.

Mars is only about one and a half times as far from the Sun, but the distance is squared: 1 / 1.524² is approximately 0.43. Its elliptical orbit means the real solar flux changes through the Martian year. The preset is a stable comparison, not a weather forecast or a daily measurement.

Solar panels can work on Mars, as several missions have demonstrated. However, 586 W/m² above the atmosphere does not become 586 watts of electrical power from a one-square-meter panel. Atmospheric dust can reduce incoming light, deposited dust can cover the cells, and conversion efficiency, tilt, temperature, nighttime, and storage all affect usable power.

NASA’s InSight mission provides a concrete example: dust accumulation progressively reduced its solar power, and the mission ended in 2022 after its energy supply was exhausted. The InSight mission report explains that outcome. This simulator isolates the distance effect so it can be understood before those engineering constraints are added.

How Bright Is the Sun on Jupiter?

At Jupiter’s 5.203 AU reference distance, incoming sunlight is about 50.28 W/m², or 3.69% of Earth’s reference. Earth receives about 27.07 times as much energy per square meter.

Solar energy remains useful at this distance, but collecting enough requires careful design. NASA’s Juno spacecraft used large solar arrays to operate near Jupiter. Its example connects the inverse-square calculation to a real spacecraft power budget; it does not mean every mission can use the same design.

Jupiter has no Earth-like solid surface. This value describes an unobstructed reference location at its solar distance, before cloud absorption or an eclipse by the planet. JPL’s Juno solar-power explanation describes the challenge.

How Bright Is the Sun on Saturn?

Saturn receives about 14.96 W/m² at 9.537 AU, equivalent to 1.10% of Earth’s sunlight. The Earth reference is about 90.95 times stronger.

Saturn’s reference distance is about 1.83 times Jupiter’s, so its incident solar flux is only about 30% of Jupiter’s. This is a useful intermediate comparison: doubling a large distance still reduces irradiance by approximately four, just as it does near Earth.

Saturn is a gas giant without an ordinary solid observing surface. Rings, cloud layers, and shadowing can change a particular location’s illumination. The tool excludes those local effects and compares the energy available in unobstructed space.

How Bright Is the Sun on Uranus?

At Uranus’s 19.189 AU reference distance, solar irradiance is about 3.70 W/m², or 0.27% of Earth’s sunlight. That is about one part in 368.22 of the 1 AU reference.

The large reduction follows directly from squaring a distance of roughly nineteen AU. A linear graph would squeeze this value close to zero beside Mercury’s. The simulator’s logarithmic axes keep the ratio readable without artificially enlarging the numerical amount of energy.

Uranus is an ice giant without an Earth-like solid surface. The reference flux does not specify cloud-top illumination, the distribution between hemispheres, or seasonal lighting at a particular latitude. Those questions require geometry and atmospheric modeling beyond distance alone.

How Bright Is the Sun on Neptune?

At Neptune’s 30.070 AU reference distance, sunlight is about 1.51 W/m², or 0.11% of Earth’s sunlight. Earth’s reference is approximately 904.20 times stronger.

That is a small energy supply, but it does not mean sunlight disappears or that Neptune is always completely dark. An unobstructed location still receives radiation from the Sun. Actual sky appearance depends on the atmosphere, viewing direction, exposure, and visual adaptation.

Neptune has no ordinary solid surface for an observer to stand on. The NASA Neptune guide gives broader planetary context. To separate the two effects of distance, compare this energy result with the Sun’s apparent size from each planet: angular diameter and received power are different quantities.

Neptune’s solar distance does not determine its own local gravity. Explore your weight equivalent under Neptune’s reference gravity for that separate comparison.

How Bright Is the Sun on Pluto?

At Pluto’s 39.482 AU reference distance, incoming sunlight is about 0.87 W/m², or 0.06% of Earth’s sunlight. Earth receives roughly 1,559 times as much solar energy per square meter at 1 AU.

Pluto is a dwarf planet, rather than a ninth planet in this comparison. Its elongated orbit changes its actual distance from the Sun substantially. The preset uses NASA’s mean J2000 semimajor axis as a fixed reference, not a live distance or an orbital average of solar flux.

This small energy input does not mean the Sun vanishes or that Pluto is always dark. The value describes a receiver facing the Sun outside the atmosphere; it does not model local terrain, surface reflection, or human vision. Compare it with the Sun’s apparent size from Pluto.

Why Does Sunlight Get Weaker With Distance?

The Sun’s energy spreads outward through space. Imagine nested spheres centered on the Sun. A sphere with twice the radius has four times the area, so the same outgoing power is distributed across four times as many square meters. Each square meter receives one-quarter as much.

Enter 2 or 3 in the distance box to reproduce these examples. The model assumes an unobstructed receiver perpendicular to the rays and a fixed solar output. It does not include atmospheric transmission, reflectivity, seasonal geometry, or internal planetary heat. A tilted receiver intercepts less energy per unit area than a directly facing one.

Does Less Sunlight Mean a Darker Sky?

Lower irradiance means less incoming energy per square meter. It does not directly specify a sky color, a visual impression, or the brightness of a photograph. Irradiance in watts per square meter includes infrared and ultraviolet energy; perceived brightness also depends on how the eye responds to different wavelengths.

Atmospheres redirect light, while human eyes adapt and cameras change exposure. A black space background therefore does not demonstrate that daylight at a distant planet is absent. The warm shading in this tool is an educational cue; the graph and numeric ratios carry the quantitative comparison.

The Sun Size Simulator answers how wide the solar disk appears. This tool answers how much energy reaches a receiving area. Neither is a calibrated view through human eyes.

Explore the Solar Energy Map

Distance also sets the time sunlight spends in transit. Compare how long sunlight takes to reach each planet with the animated light-travel simulator.

Distance sets the starting energy budget, while atmospheres and geometry shape local conditions. Try a custom distance, compare a neighboring planet, then open the interactive Solar System Map to put the reference orbits into context.

Sources and calculation method

• NASA Pluto Fact Sheet — Pluto’s mean J2000 semimajor axis, 39.48168677 AU; Pluto is a dwarf planet.
• NASA Goddard: Solar Irradiance Science — the approximately 1,361 W/m² baseline and its variability.
• NASA JPL: approximate planetary elements, Table 1 — fixed J2000 semimajor axes reused from Celesiq’s orbital model. Earth is normalized to exactly 1 AU.

The reference model holds solar output fixed and calculates total incident flux at the chosen solar distance. It is not a live solar monitor or an orbital average.