Our home earth is the 3rd planet from the sun and is home to all current known life. It has a fairly thick atmosphere made up of predominantly Nitrogen and Oxygen.

Pressure 1013.25 millibars
Gravity 9.81 m/s²
Diameter 12,742 km

This is our nearest planet and is the 4th planet from the sun it has an atmosphere that is much thinner than earth and it is made up predominately of Carbon Dioxide and Nitrogen.

Pressure 6.0 mbar
Gravity 3.71 m/s²
Diameter 6,779 km

Our moon is in orbit around earth which causes our tides, due to its small size it has almost no gravity and a much smaller atmosphere than earth.

Pressure Almost Zero
Gravity 1.622 m/s²
Diameter 3,474 km

Venus is the 2nd planet from the sun it has a very thick atmosphere which is around 4 times the density of the atmosphere on Earth it is composed mainly of Carbon Dioxide. With an average surface temperature of 462 degrees Celsius it is considered very inhospitable to life.

Pressure 92 000 mbar
Gravity 8.87 m/s²
Diameter 12,104 km

The dream of some scientists is to terraform Mars so that it is suitable for humans in such a way that we would not need to wear a space suit and only a gas mask. One day Mars may be suitable for general humans if its atmosphere is heavily modified.

Pressure 190 millibars
Gravity 3.71 m/s²
Diameter 6,779 km

67P/Churyumov–Gerasimenko is a Jupiter-family comet that became famous last year, when the Rosetta probe approached it and landed the Philae probe on its surface. The informations that we are receiving from Rosetta are revolutioning our knowledge on comets.

Pressure Almost Zero
Gravity 0.001 m/s²
Diameters from 4.1 km to 2.8 km

Millibars is a unit of pressure humans need a certain amount of pressure to keep them alive and to keep water which makes up 75% of our bodies in liquid. If the pressure gets to low the water at body temperature turns into a gas. This level of pressure is often called the “Armstrong Limit” which is 62 millibar.

This is measured in m/s² which is the speed that an object would fall in a vacuum in meters per second. For example on earth where gravity is 9.81 m/s² this would mean that after 1 second it would be falling at 9.81m every second and 19.62m every second after 2 seconds of falling. A vacuum means the absence of air.

This is how wide the planet is at its furthest point

This is the starting velocity that your rockets begin falling at particularly when deorbiting a planetary body rockets can fall at very high velocities in excess of 1000m/s

This is a calculation that is done to work out the amount of drag an object experiences when moving through a fluid environment in this context that can mean water or air but for us its the effect that this has on its atmospheric conditions that’s important.

We have listed some examples below showing the shape and its numeric drag coefficient you can see what a large difference the shape of it makes!

This varies a huge amount by planets one thing to consider is that its not only the pressure that effects the drag but also the density of the material that it is passing through as a result we have listed the density in KG/M³