Which planets are the youngest and oldest in our solar system?

Illustration of the solar system, showing the paths of the eight major planets as they orbit the Sun, plus the asteroids and comets. The four inner planets are, from inner to outer, Mercury, Venus, Earth and Mars. The four outer planets are, inner to outer, Jupiter, Saturn, Uranus and Neptune.

About 4.6 billion years ago, a celestial cloud collapsed, paving the way for our solar system to form. Then, a nebula with strong gravitational pull took shape, kick-starting the birth of the sun. But after that, the details leave more room for debate about which planets formed first.

So, what do we know about which planets emerged early, and which ones developed later on?