Life on Earth

[starstruk]

this question just popped in my head,if someone with the same telescopes that we have looked at Earth from Venus or Mars,could they tell that there is life here?

Daft question I know

[RobH]

Without much consideration, I would say that visually, with the sort of scopes that we use, it would be tricky from venus as most of the earths surface would always be illuminated by the sun from your perspective.

From Mars you would get a chance to see the night side, and would see cities, but would you know that's what they were?

Stick a spectroscope on though, and you'd get all the indicators of life with a large fossil fuel based industrial civilisation rapidly making a mess of it.

Good question

Cheers

Rob

[Tim]

Not using a telescope, but other instruments, you could detect the signs of life as Rob says.

Mind you, if they happened to catch the UK on the dark side, they'd see all the lights that make our nights so bright

[brianb]

Stick a spectroscope on though, and you'd get all the indicators of life with a large fossil fuel based industrial civilisation rapidly making a mess of it.

And if you'd used the spectroscope 2.5 billion years ago you would have known instantly that there is life at work .... you can't get an atmosphere containing significant amounts of free oxygen otherwise.

[Catanonia]

Wouldn't the TV signals and satellites give us away

[brianb]

Wouldn't the TV signals and satellites give us away

Not with an optical scope. But there is a serious issue here; any intelligent alien "tuning in" to the barrage of TV soaps & reality shows emanating from our planet would very likely (and in my opinion accurately) conclude that life is present, but that its intelligence is too low to measure.

[beamish]

Not with an optical scope. But there is a serious issue here; any intelligent alien "tuning in" to the barrage of TV soaps & reality shows emanating from our planet would very likely (and in my opinion accurately) conclude that life is present, but that its intelligence is too low to measure.

Agreed