# What is the total mass of orbiting interplanetary unbound atoms in the solar system?

Excuse the poor phrasing of the title, but it became apparent to me that the solar system has some degree of density (i.e it is not a perfect vacuum). So my question is if any of these particles (not bound with others like the moon, debris, dust etc) are orbiting the earth, and if so, the total mass of them. Note, I'm distinguishing this from gas in our atmosphere by defining them as particles that are solely at the height they are at due to their orbits.

Britannica suggests a density for neutral hydrogen at 0.01 atom per $$\text{cm}^3$$. There might be some heavier atoms as well, but then again most of that material isn't in orbit. So I think it's conservative to assume they're all hydrogen and in orbit if close enough.
The Hill sphere for earth is about 100 million km in radius, or $$4 \times 10^{39} \text{cm}^3$$. Assuming one hydrogen atom for each 100, you get a mass of $$7 \times 10^{10} \text{kg}$$. That's about the same as asteroid Bennu.