Earth Flag

Looking at the moon the other night, i was struck with the thought 'Does anyone own the moon'?
I did find that there is an 'Outer Space Treaty' which says nobody can lay claim to it as it is for all of mankind and nobody is allowed to put any weapons on it or testing weapons of any kind, conduct military manoeuvres or establish a military base on it or any other celestial body either.
There are a few American flags on it but as the Moon is 'for mankind', why didn't the Americans use something more representative of our planet and then i realised we don't have an Earth flag.
Does seem a bit of a oversight, especially as we are starting to creep outside of our own sphere and onto other planets and sticking flags in things is what we humans have always done.
Apparently there have been a few moves to agree to a 'Earth Flag' but none have really gained any traction so we are still flagless.
The obvious choice would be the Olympic or UN flag's but there are a few others that have gained recognition but my favourite would be the effort by James W. Cadle who designed the above in 1970. The blue circle representing Earth in the centre with a segment of a large yellow circle representing the sun and a small white circle for the moon, all on a black background has been adopted by SETI and is as close as we have to a 'Earth Flag'.
Maybe next time when China. America or the Russians land on the Moon or Mars or some other rock outside our atmosphere, we can plant the Earth Flag and not the flag of any individual country.