Our solar system
A planet is a star with three major characteristics: to be in orbit around a star, to have a more or less spherical shape and to have created a vacuum around it (that is to say, to no longer have a body of size comparable to its own in a close orbit).
![](https://www.ompe.org/wp-content/uploads/2023/01/1.jpg)
The main planets in our solar system are:
Mercury
Surface with many craters, due to meteorite impacts / presence of ice at the poles / non-existent atmosphere except for the presence of traces of gas / large temperature differences between -172°C to 427°C / no satellite.
![](https://www.ompe.org/wp-content/uploads/2023/01/2.jpg)
Venus
Surface with many mountains, canyon, volcanoes and riddled with craters without any trace of water / atmosphere composed of carbon dioxide (CO2), nitrogen (N2), sulfur dioxide (S2) and sulfuric acid ( H2S) / very important greenhouse effect / average temperature of 453°C / no satellite.
![](https://www.ompe.org/wp-content/uploads/2023/01/3.jpg)
Earth
Surface rich in minerals, presence of crater and varied relief / large quantity of water (in different forms but essentially salty), characteristic of the presence of life / atmosphere composed of nitrogen (N2), oxygen (O2), d argon (Ar), carbon dioxide (CO2), water vapor (H2O) and other gases / temperatures varying between -60°C and 50°C / known satellite The Moon.
![](https://www.ompe.org/wp-content/uploads/2023/01/4.jpg)
March
Red surface characterized by the presence of hematite (mineral species composed of iron oxide, titanium, aluminum), manganese and water) with a very varied relief and numerous craters) / presence of ice at the poles / atmosphere composed of carbon dioxide (CO2), nitrogen (N2), argon (Ar) and oxygen (O2) / significant temperature differences between -123°C to 37°C / presence of strong winds / two known satellites Phobos and Deimos.
![](https://www.ompe.org/wp-content/uploads/2023/01/5.jpg)
Jupiter
Largest planet in the solar system / no trace of water / significant atmosphere composed of hydrogen (H2), helium (He), ammonia (NH3), methane (CH4) and ethane (C2H6) / temperature outside the clouds around -153°C / strong winds that can reach more than 500 km h / 67 known satellites including Ganymede, Lo and Europe.
![](https://www.ompe.org/wp-content/uploads/2023/01/6.jpg)
Saturn
Presence of thousands of colored rings made of ice and rocks / no trace of water / significant atmosphere composed of hydrogen (H2), helium (He), ammonia (NH3) and methane (CH4) / temperature outside the clouds about -185°C / 62 known satellites including Titan.
![](https://www.ompe.org/wp-content/uploads/2023/01/7.jpg)
Uranus
Qualified as an ice giant / presence of greenish gases forming an atmosphere of hydrogen (H2), helium (He) and methane (CH4) / no trace of water / temperature outside the clouds around -214°C / 27 known satellites.
![](https://www.ompe.org/wp-content/uploads/2023/01/8.jpg)
Neptune
Qualified as an ice giant / presence of bluish gases forming an atmosphere of hydrogen (H2), helium (He) and methane (CH4) / no trace of water / temperature outside the clouds around -225°C / strong winds that can go to more than 2000 km h / 14 known satellites.
![](https://www.ompe.org/wp-content/uploads/2023/01/9.jpg)
These planets fall into three main groups:
A. Terrestrial planets, essentially composed of rocks and metals, also possessing a solid surface. This is the case for Mercury, Venus, Earth and Mars, which have several solid envelopes (usually three: the crust, the mantle and the core).
![](https://www.ompe.org/wp-content/uploads/2023/01/10.jpg)
B. The Jovian planets, essentially composed of gaseous elements and are the largest in our solar system. They have a thick atmosphere (even if they are gaseous) and would probably have a solid rocky core according to scientific research. This is the case for Jupiter, Saturn, Uranus and Neptune.
![](https://www.ompe.org/wp-content/uploads/2023/01/11.jpg)
C. Dwarf planets, a recently created category, have the main characteristics of planets, but with the difference that they share their orbit with other bodies such as asteroids. Below are the five planets concerned:
Eris
The most massive known dwarf planet, located beyond the Kuiper belt, discovered in 2003 and identified in 2005.
![](https://www.ompe.org/wp-content/uploads/2023/01/12.jpg)
Pluto
The largest known dwarf planet, located after Neptune in the Kuiper belt, discovered in 1930.
![](https://www.ompe.org/wp-content/uploads/2023/01/13.jpg)
Makemake
Third largest known dwarf planet, located in the Kuiper belt (after Neptune), discovered in 2005.
![](https://www.ompe.org/wp-content/uploads/2023/01/14.jpg)
Haumea
Located in the Kuiper belt (after Neptune), discovered in 2004.
![](https://www.ompe.org/wp-content/uploads/2023/01/15.jpg)
Ceres
Located in the asteroid belt between Mars and Jupiter, discovered in 1801.
![](https://www.ompe.org/wp-content/uploads/2023/01/16.jpg)