When we look at the night sky, what we usually see first is the Moon and its pocked surface. Its scars are an early warning that the realm beyond the confines of our atmosphere is a dangerous place.
By retrieving Moon samples we’ve learned that very early on, the Earth and Moon were once part of the same planet, the ‘proto-Earth’.
It collided with another planet, undoubtedly the most cataclysmic event in Earth’s history. The impact ejected huge volumes of planetary material into space where it coalesced into a ring, and then into our Moon. The Earth continues to ‘wobble’ from the impact billions of years later, which causes the seasons.
Looking further into space…
We see other planets both somewhat similar to our own…
And very different.
But all of them orbit our Sun, the giant heat-and-light giving behemoth at the centre of our solar system.
Early on in its history, perhaps before the collision that formed the Earth and Moon, there was a huge explosion originating from the Sun. It pushed most of the lighter gasses away from itself, stripping them from the closer planets and pushing them towards the more distant planets.
They swelled with the huge volume of new material and became ‘gas giants’. The solar system would thereafter be split into rocky inner planets and gaseous outer giants.
The solar system also contains many smaller bodies, including moons (who orbit planets) and asteroids (who orbit the Sun, but aren’t large enough to be considered planets).
Reddit community, The distance from the Earth to the Sun, when the Earth is one pixel in diameter
Except the sun is totally not that size, it's more than 200 pixels wide on this image despite the fact that its diameter is about 100 times that of the Earth. There are exactly two things to get right for this "visualization" and you managed to screw up one of them.
Reddit community, The distance from the Earth to the Sun, when the Earth is one pixel in diameter
‘How the sky would look if the planets were as close as the Moon’, by Ron Miller.
Unaltered photo of the moon…
If Mercury were where the moon is…
Venus
Mars
Jupiter
Saturn
Uranus
Neptune
Ron Miller, What if we had a planet instead of a Moon?
And a different version, in GIF, is here.
Stars like our Sun are likely common throughout space, being just one of 400 billion in our Milky Way galaxy. Most of these stars are orbited by planets (called ‘planetary systems’) and potentially some host planets with life or civilisations.
The stars of our galaxy move together in a slow spiral around a ‘supermassive’ black hole, over 4.5 million times as massive as our Sun.
We can see about 2 trillion other galaxies in our universe, and they move in great, slow formations. On this scale the universe has a foamy texture, with galaxies concentrated in great ‘filaments’ as they are drawn to each other’s gravity.
There are likely to be vastly more galaxies beyond what we can see.
With all this space, the universe must be full of wonders beyond what we can possibly imagine.
