Plate 24 · Space
The Solar System Today
This is the solar system as it is today: the eight planets where orbit data from NASA’s Jet Propulsion Laboratory puts them. The farther a planet is from the Sun, the slower it moves and the longer its year — a rule Johannes Kepler found four centuries ago.
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The Inner Planets Now
Mercury, Venus, Earth and Mars are closest to the Sun: the four rocky planets. Here is where each one is on its orbit today.
Every orbit is an ellipse, though most are very close to circles. Mercury’s is the most stretched: its farthest point from the Sun is about half as far again as its nearest.
Planet positions: JPL Horizons · planets drawn much larger than life
The Inside Track Is Faster
Run time forward and watch: Mercury goes around the Sun in 88 days, Earth in a year, Mars in nearly two.
The farther out a planet is, the weaker the Sun’s pull, so it moves more slowly — and it has farther to go. Kepler found that, for every planet, the square of the time a lap takes is proportional to the cube of the orbit’s size.
The Giants Outside
Farther out are Jupiter, Saturn, Uranus and Neptune, the four giant planets. They are so far away that the inner planets’ orbits crowd into the middle, barely visible.
Jupiter takes nearly 12 years to go around the Sun; Neptune takes 165. Since it was discovered in 1846, it has gone around just over once.
How Long Sunlight Takes
Light travels about 300,000 kilometres a second, but the solar system is enormous. Sunlight takes a little over 8 minutes to reach Earth, more than 40 minutes to reach Jupiter, and about four hours to reach Neptune.
So the Sun you see is the Sun of 8 minutes ago.
All in a Row
Line up the Sun and the eight planets at their true sizes. Jupiter is 11 times as wide as Earth, and the Sun is 10 times as wide as Jupiter. It would take more than a hundred Earths side by side to span the Sun.
Sizes to scale · distances not to scale
Your Turn
Drag the date to see where the planets were and will be. Speed time up and see which planets lap which.
Try thisWhile the Earth goes once round the Sun, how far does Jupiter get?
What the model leaves out
The orbits are drawn to true scale, but the planets are drawn hundreds to thousands of times too big, and the Sun tens of times; otherwise they would be invisible in a picture this size. Positions come from JPL’s orbital elements for 11 October 2026, carried forward with Kepler’s laws. Far from today, the planets’ pulls on one another make this drift, but over a few decades the difference doesn’t show at this scale.
A common misreading
The planets don’t circle the Sun in a neat line, as some pictures show them; that is only for looks. Each planet moves on its own orbit at its own speed, and they almost never line up in a straight row. Also, Earth’s distance from the Sun barely changes through the year; it is not what causes the seasons; the seasons come from the tilt of Earth’s axis.
Sources
- NASA/JPL: Horizons system
- NASA: Our solar system
- NASA: Orbits and Kepler’s laws
- NASA: Planetary fact sheet
Data
Planetary orbits: JPL Horizons, Solar System Dynamics Group, NASA/JPL-Caltech. Mercury, Venus, Mars, Saturn and its rings, Uranus and Neptune: Solar System Scope textures (solarsystemscope.com), CC BY 4.0, colours of Venus, Mars, Neptune and the rings adjusted; Jupiter: NASA/JPL/Space Science Institute, Cassini (PIA07782). Earth: NASA Earth Observatory, Blue Marble Next Generation, October 2004 (Reto Stöckli); city lights, NASA Earth Observatory Black Marble 2016 (Joshua Stevens, Miguel Román, Suomi NPP VIIRS); clouds, NASA Blue Marble 2002 (Reto Stöckli, NASA GSFC). Stars: Yale Bright Star Catalogue, 5th revised edition (Hoffleit & Warren 1991), via CDS VizieR. Milky Way: NASA/Goddard Space Flight Center Scientific Visualization Studio, Deep Star Maps 2020; Gaia DR2: ESA/Gaia/DPAC.
Follow the question
Plate 18The Space Station Is FallingAstronauts float not because there is no gravity in space, but because they and their station are always falling.
Plate 03The Shadow of the MoonThe Sun is about 400 times wider than the Moon, and about 400 times farther away. That coincidence lets day turn to night for a few minutes.
