Astronomical Unit

Did you know in the 1700s astronomers used horizontal parallax to determine accurately the distance between the Sun and the Earth by using Venus traveling across the Sun.

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Oneofthestormboys · 56-60, M

Yep!
It’s amazing how all these things were discovered in the first place isn’t it?

Lisa82 · 41-45, F

@Oneofthestormboys The thing that always amazed me was people discovering elements that are not visible like all the gases

Oneofthestormboys · 56-60, M

@Lisa82 And compared to nitrogen and oxygen (and a bit of CO2) there so very little of them in our atmosphere too… I think combined it’s about 1%…