On this page you can interactively compare the 8 planets of our solar system by choosing a comparison parameter. The values of the planets are shown as bars in the following order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
The diameter of the planets was already compared on the Size comparison page.
Of course Jupiter is the leader in this ranking. Roughly speaking 2 Earth diameters behind there is Saturn, while
Uranus and Neptune show nearly the same values, as well as Earth and Venus. Mars and Mercury are the smallest planets.
This comparison also shows the difference between the gas giants Jupiter, Saturn, Uranus, Neptune and the rocky planets
Mercury, Venus, Earth, Mars.
The planets travel around the sun on an elliptic orbit. That means that the distance to the sun is changing. The average
distance to the sun is now the mean value of those distances seen over a whole revolution.
As I ordered the planets to their distance to the sun, it is no surprise that the average distance is increasing from
left to right. But it is amazing how the distances increase from planet to planet. Sometimes the distance of a planet is
double the distance of the previous one. Also the values itself are incredible. For example the average distance between
Earth and sun is 150 million km. This means you have to drive with you car at a speed of 100 km/h for 171 year to reach
the sun from our planet. Even the light takes 8 Minutes to travel this distance.
Because of those large distances the Sun-Earth-Distance of at about 150 Million km has been named
Astronomical unit (AU).
When this unit is taken the average distances for the 8 planets would be:
Mercury - 0.39 AU, Venus - 0.72 AU, Earth - 1 AU, Mars - 1.52 AU, Jupiter - 5.19 AU,
Saturn - 9.51 AU, Uranus - 19.14 AU, Neptune - 29.99 AU
The planets are traveling around the sun on elliptic orbits. The speed on those orbits is changing.
The smaller the distance to the sun, the faster moves the planet. The slowest speed is reached when the planet
is at the position furthest away from the sun. The average speed is the constant velocity that the planet would need
to complete a revolution in time.
Here a connection can be seen between the average speed and the distance to the sun. A planet that is nearer to the sun
is faster on its orbit. Mercury is the fastest planet with an average speed of 48 km/s. This does not sound very
spectacular. But when we consider that 100 km/h would be 0.028 km/s we can imagine that this is a huge velocity.
Mercury is traveling with 172,800 km/h around the sun. The Earth for example is moving with a mean velocity of 108,000 km/h.
Jupiter and Saturn are on top concerning the number of moons. So they and their moons are planetary systems on their own within
our solar system. Also Uranus and Neptune have a high moon count. In the last century several small moons have been discovered for
them. For example in July 2013 the 14th moon of Neptune has been detected on pictures of the Hubble telescope. So it is hard to
be up to date for this statistic. That is the reason why I reference the values of the Wikipedia pages.
The rocky planets show here completely different values. Mercury and Venus do not have any moon. Mars has two small moons.
One of them is getting closer to Mars, the other is drifting away slowly. The Earth and our Moon is also referenced as
Double planet, because our Moon is relatively large
compared to the size of the Earth. (The proportion of the Earth-Moon-Diameter is 1 to 0.27. In comparison to that the
proportion of the Jupiter-Ganymet-Diameter is 1 to 0.037, although Ganymed has a diameter of 5,262 km, which is larger than the diameter
of Mercury.)
The axial tilt is the angle between the axis of rotation and the perpendicular to the orbital plane of the planet. The
axial tilt of 23.44 degrees of the earth is responsible for the seasons, because the northern and the southern
hemisphere receive a different magnitude of solar irradiation at different points on the orbit.
Concerning the other planets especially Venus and Uranus show interesting values. Uranus has an axial tilt of 97 degrees,
which means it is nearly rolling on its orbit. The Venus actually has an axial tilt of 2.7 degrees, but then the
direction of the rotation would be atypical. The sun would rise in the west and would set in the east. It is assumed
that Venus performs a headstand, which explains the axial tilt of 177.3 degrees.
The orbital inclination is the angle between the orbital plane of the planet and the orbital plane of the Earth. The differences between the planets are very small. Only Mercury has a higher value.
The eccentricity measures the deviation of the planet's orbit shape from a circle. A value of 0 means that the orbit is a perfect circle. A value of 1 would represent a line. The comparison shows that Venus and Neptune have an orbit that are nearly a circle. Mercury has an orbit with high eccentricity.
The duration of a revolution around the sun says how long a year of the planet lasts in days.
We already saw that the speed of the planets on their orbits descends with their distance to the sun.
So it is no surprise that the duration of the revolutions is growing with the planet's distance to the sun.
For me it is interesting how much time the gas giants take for their revolution around the sun. While
Mercury's year only lasts for 88 days, Neptune's year has a duration of 164 Earth years.
A human at age of 84 years would have experienced one Uranus year! Compared to that
the Saturn year (29.4 Earth years) and the Jupiter year (11.8 Earth years) are rather short.
Mars takes 1.88 Earth years to travel around the sun.
The rotation duration tells how long it takes that the planet turns around its own axis. Here we see a very
interesting result. The inner planets Mercury and Venus have a very slow rotation. Venus takes even longer to
rotate around its own axis than it takes the planet to travel around the sun. That means the day on Venus lasts longer
than the year.
Jupiter and Saturn show a different extreme. Although their giant dimensions they rotate around their own axis
within 10 hours. Uranus and Neptune are only a little bit slower.
The surface gravity is measure for the power of attraction of the planet. So you can calculate how much
weight an object has on other planets, when it weighs 100 kilograms on Earth.
On Jupiter such an object would weigh 213.3 kg (= 100/9.8 * 20.9), while on Mars the same object would weigh 37.7 kg
(100/9.8 * 3.69).
A good example for a website where you can calculate your weight on a different space object is
the Exploratorium.
(The weight on Jupiter for a 100 kg object on Earth is calculated as 236.4 kg, but I rely on the
data of my books.)
The escape speed is the velocity that an object must have to get away of a planet. The Earth's escape speed is 11.18 km/s.
For me it is helpful to calculate the km/h value to see how fast this really is. So to shoot an object away from the
Earth you need to accelerate it to a speed of 40,248 km/h. Rockets only need 28,000 km/h to reach a balance between
the Earth's gravity and the centrifugal force, so that they can be in an orbit around the Earth. But to escape
the Earth's gravity completely they would need 11.18 km/s.
To get away from Jupiter an object must fly with 181,880 km/h. To escape a black hole the object must be faster
than the light, which is not possible.
The minimum temperature of -173 °C of Mercury is a little bit surprising as this planet is so near to the sun.
But Mercury has a very thin atmosphere and as the day on Mercury lasts 53 Earth days one half of the planet
sees no sun for a long time and cools down. The minimum temperature of 243 °C on Venus on the other hand is not
caused by the proximity to the sun. The very dense atmosphere and its greenhouse effect produce those high temperatures.
The temperatures of the outer planets decrease with their distance to the sun.
Mercury's maximum temperature of 427 °C is lower than the maximum temperature of Venus, although Mercury
is nearer to the sun. But the atmosphere of Venus, which promotes the greenhouse effect, causes this high temperature.
The temperatures of the outer planets decrease with their distance to the sun.
The differences between the minimum and the maximum temperatures of the planets show interesting results.
While the side of Mercury that looks at the sun gets heated up to 427 °C, the other side cools down to -173 °C.
On Venus the dense atmosphere avoids that their are significant temperature differences.
For me it is also interesting that Mars shows nearly the same temperature differences as the Earth, but
Mars is at about 40 °C cooler. A really hot Mars summer reaches only 17 °C.
The atmospheric pressure on the surface of a planet is only available for the rocky planets. The gas giants
do not have a hard surface. On them the pressure is constantly ascending until the core of the planet is reached.
Scientists estimate that the pressure in the core of Jupiter is 30 million times higher than the air pressure
on the Earth on sea level. The reason for this is the weight of the gas that surrounds the core of Jupiter.
The comparison of the rocky planets shows that Mercury has nearly no atmosphere. Also Mars has a very thin atmosphere.
Venus in contrast has a very high pressure. So on Venus objects not only get boiled they also get crushed.
It is no wonder that probes that landed on Venus could only send data to Earth for a few minutes.
The density of planets is a measure that distinguishes rocky planets from gas giants. To explain the values of
the density I want to mention two extremes: The density of iron is 7.874 g/cm³, while the density of water at a
temperature of 4 °C is 1 g/cm³.
You can see that the rocky planets with their heavy iron cores have a rather high density. Only Mars stays a little bit
behind. As the gas giants mainly consist of gas, their density is much smaller. The density of Saturn is even
smaller than the density of water.