Your weight changes across the Solar System

Start with an 85 kg space panda.
Then try your own weight.

Giant panda in a spacesuit standing on the Moon.

Your mass stays the same everywhere. But weight, what a scale reads, depends on gravity.

Weight across the Solar System

Start with Jupiter: why doesn't 318x the mass mean 318x the weight?

Earth weight85 kg

Choose an option below to compare how fast gravity pulls the panda down.

Celestial body	Gravity × Earth	Weight
Sun	27.93×	2374 kg
Jupiter	2.53×	215 kg
2.53× Earth gravity Surface gravity Jupiter Jupiter is 318 times more massive than Earth, but its huge size spreads that mass out — so its surface gravity is only about 2.5× stronger.
Neptune	1.14×	97 kg
Saturn	1.06×	90 kg
Earth	1×	85 kg
Uranus	0.90×	77 kg
Venus	0.90×	77 kg
Mars	0.38×	32 kg
Mercury	0.38×	32 kg
Moon	0.17×	14 kg

* You couldn't actually stand on the Sun, Jupiter, Saturn, Neptune, or Uranus.

Gravity essentials

What falls faster?

If dropped in a vacuum, which would reach the ground first?

No air. No fluttering. Just gravity.

More distance = less gravity.

Like light spreading out from a bulb, gravity drops fast with distance:

By Neptune, the Sun's pull is about 6,000x weaker than at Mercury.

Jupiter is 318× more massive than Earth. So why isn't its gravity 318× stronger?

Jupiter's surface is much farther from its centre than Earth's surface is. Gravity gets weaker with distance, so at Jupiter's cloud tops the pull is only about 2.5× Earth's gravity.

For a round planet or star, gravity behaves as though the object's mass is pulling from its centre. So surface gravity depends on both mass and distance from the centre. A farther surface means weaker surface gravity.

Three pulls shaping your everyday life

The Earth

Holds the atmosphere, keeps your feet on the ground, and keeps the oceans in their basins.

The Sun

150 million kilometres away, yet massive enough to lock the Earth into a yearly orbit.

The Moon

Much smaller and closer—its gentler pull stretches the oceans into tides twice a day.

Everything with mass pulls on everything else.

Your phone and your cup are pulling on you and each other right now, but you only feel gravity when one of the objects is truly massive, like the Moon or the Earth.

When you jump the earth jumps up to meet you, but only by the width of the nucleus of an atom, so you don't notice.

Right now Jupiter, Saturn, Mars and distant stars are pulling on you, but so weakly that it makes no measurable difference to your life.

Potato or ball?

Gravity pulls toward the centre from every direction.

If a body gets big enough, that inward pull starts smoothing it into a sphere.

Below roughly 500 km, many objects still look like potatoes. Icy bodies can become rounded at smaller sizes than rocky ones, because ice deforms more easily than rock.

Here are three real objects near that boundary: one still potato-shaped, one more in between, and one rounded into a ball.

Hyperion

Potato-shaped

410 × 260 × 220 km
A moon of Saturn

Potato-shaped

Vesta

Ceres

Rounded into a ball

940 km
A dwarf planet

Clearly rounded

Orbits

Too slow

It falls down.
Gravity pulls it into the body.

Just right

It falls around.
Its sideways speed keeps it missing the surface, again and again. That is an orbit.

Too fast

It flies away.
Its speed carries it beyond the body's grip.

Gravity never ends.

There is no "off switch" - it acts over any distance, just increasingly weakly.

Neptune is not the edge. Not even close.

Next: Beyond the Planet Zone 5/6