Why do different planets have different atmospheres?

Answer 1

All the sun's planets probably had similar atmospheres when they first formed, billions of years ago. The most common gases were the light gases, hydrogen and helium, with smaller amounts of oxygen, nitrogen and other gases.

The immense gravity of the giant planets, Jupiter, Saturn, Uranus and Neptune, was able to hold the hydrogen and helium, which remain the predominant gases in their atmospheres, along with methane formed by the combination of hydrogen with free carbon. However, hydrogen and helium gradually escaped from the atmospheres of the smaller planets, where gravity is insufficient to hold the light gases permanently.

Even the heavier gases, such as oxygen and nitrogen, as well as carbon dioxide and water vapour, can gradually escape from smaller planets, such as Mars and Mercury. So, these planets now have quite thin atmospheres. The Moon and other small bodies in the solar system have essentially no atmosphere.

In our solar system, only the Earth and Venus are the right size to lose most of the light gases, while retaining gases such as oxygen, nitrogen, carbon dioxide and water vapour.

Answer 2

Venus has a green house gass effect that makes it even more hot than mercury, which is the closest planet to the sun. That makes a difference in the atmosphere. There are no oceans on Venus or vegetation, and that also makes a difference, so our atmospheres are very different.

Answer 3

There are lots of factors as each planet is different. The main factors are where they are in relation to the sun and what they are made of. Earth is a terrestrial planet and has an atmosphere that we can survive in. The gas giants have no solid surface and are just giant balls of gas. Mercury and Venus are nearer to the sun than we are, so they are very hot and that affects the atmosphere.

Answer 4

Different planets have different atmospheres due to variations in their composition and distance from the sun. Factors like the planet's size, gravity, and proximity to the sun determine what gases are retained in the atmosphere, leading to unique compositions. Active processes like volcanic activity and biological activity can also contribute to the diversity of atmospheric compositions across planets.

Answer 5

All.