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Solar system
Our solar system was doing just fine without humanity for 99.995% of its lifetime

Our Solar System is quite “young”, at least as far as solar systems go. Using radiometric dating, scientists were able to determine that most of its ingredients, including the sun and the planets, are just over 4.6 billion years old (while one of the oldest stars detected is a ripe 13.6 billion years old.) By comparison, humans have been around for a “mere” 200 thousand years, a barely noticeable spec in the vastness of Solar System’s lifespan.

Lifetime of Solar system
Our Sun contains 99.86% of the Solar System's known mass

The mass of the Sun is 1.989 × 1030 kg when all the planets combined are only 2.66 x 1027 kg.

Jupiter 1.8986 x 1027
Saturn 5.6846 x 1026
Neptune 10.243 x 1025
Uranus 8.6810 x 1025
Earth 5.9736 x 1024
Venus 4.8685 x 1024
Mars 6.4185 x 1023
Mercury 3.3022 x 1023
Pluto 1.25 x 1022
Sun and planets
The hottest planet is actually not the one closest to the sun

Although Mercury is the planet nearest to the Sun, it’s actually only the second hottest planet, following Venus. Why? Mercury is tiny and doesn’t have any atmosphere, which under normal circumstances traps and holds heat. Any heat that Mercury receives from the sun quickly dissipates back into space. Venus on the other hand is very close in size to Earth and viewing it has been difficult due to a very thick atmosphere of carbon dioxide. This thick atmosphere, coupled with its close proximity to the sun, makes the surface of Venus hotter because the heat has a harder time escaping back into space.

Hottest planet
Pluto is smaller than the USA
Pluto and USA
Horizontal Width: 2,680 miles
Vertical Length: 1,582 miles
Radius: 736.9 mi
We are all citizens of the Sun

You haven't left planet Earth as long as you're still within the bounds of Earth's atmosphere (or gone beyond the Kármán line.) Similarly, Sun has it's own version of the "atmosphere", called Heliosphere, which extends far beyond our solar system. It engulfs all the planets and is responsible for some amazing experiences both in space as well as here on Earth such as the wondrous Aurora lights.

Heliosphere Aurora lights
Planets can be categorized into 3 groupings, each at different proximity to the sun
  • The inner planets (also known as terrestrial planets) are smaller and made primarily of rock and metal.
  • The outer planets can be further categorized into two sub-classes – gas giants and ice giants. These are much larger and further away from the sun:
    • The gas giants primarily consist of lighter gasses, higher up on the periodic table (e.g. H and He.)
    • The ice giants contain gases heavier than those that make up gas giants, e.g. O, C, N, S and located at the outer rim of our solar system.
Types of planets