We can't even see the planet - it is just detected by dips in the brightness of the star as they pass in front of its star.
So - depends. If they built giant space mirrors - such as have been suggested for mega-engineering projects - e.g. if they were trying to terraform another planet which we haven't seen yet - or they have huge solar panels on their way to becoming "Dyson Swarms" - or have made vast colonies of thousands of Stanford Torus type habitats - anything like that, planetary scale - we would spot that by the same method, dips in the light levels. Or increases through reflected light.
That's technology that we already have ourselves capability to build absolutely huge thin film space mirrors - within a century at least - you could see us making huge thin film mirrors in space - if we needed it for something.
There is actually an on going program to try to spot mega-architecture around stars in our galaxy, they are searching for Dyson Spheres:
Dyson Sphere search program at Fermilab
But small satellites like the ones we have around Earth already - no - no chance of spotting those with present day technology at that distance.
Hubble would struggle to spot the ISS at the distance of the Moon because the distances are so far. It couldn't resolve it as more than a couple of pixels and as a spot of light, it could spot it, but it would be faint.
So, there is no way we can spot small satellites and space stations even around nearby exoplanets directly. If they broadcast radio waves or send out laser beams that's another matter. If they broadcast laser beams directly towards Earth - assuming they know to point them in our direction at the same time we look in that direction -we could spot them at great distances - that's the idea of "optical SETI".
But - for that to work they would need to point the laser beams at us 1400 years ago. At that point they would only know Earth as it was 2800 years ago. So - why point a laser beam this way? Not likely they could detect that there is any intelligent life here. But if they had a program of sending beams of laser light in the direction of any possible habitable world in their vicinity - and had kept that up for thousands - or more likely hundreds of millions of years (still just a blink in geological time, so even that would be a remarkable coincidence that we look out for the signal within the same hundred million year long period that they were transmitting it) - then we would have a chance of spotting them.
So - depends. If they built giant space mirrors - such as have been suggested for mega-engineering projects - e.g. if they were trying to terraform another planet which we haven't seen yet - or they have huge solar panels on their way to becoming "Dyson Swarms" - or have made vast colonies of thousands of Stanford Torus type habitats - anything like that, planetary scale - we would spot that by the same method, dips in the light levels. Or increases through reflected light.
That's technology that we already have ourselves capability to build absolutely huge thin film space mirrors - within a century at least - you could see us making huge thin film mirrors in space - if we needed it for something.
There is actually an on going program to try to spot mega-architecture around stars in our galaxy, they are searching for Dyson Spheres:
Dyson Sphere search program at Fermilab
But small satellites like the ones we have around Earth already - no - no chance of spotting those with present day technology at that distance.
Hubble would struggle to spot the ISS at the distance of the Moon because the distances are so far. It couldn't resolve it as more than a couple of pixels and as a spot of light, it could spot it, but it would be faint.
So, there is no way we can spot small satellites and space stations even around nearby exoplanets directly. If they broadcast radio waves or send out laser beams that's another matter. If they broadcast laser beams directly towards Earth - assuming they know to point them in our direction at the same time we look in that direction -we could spot them at great distances - that's the idea of "optical SETI".
But - for that to work they would need to point the laser beams at us 1400 years ago. At that point they would only know Earth as it was 2800 years ago. So - why point a laser beam this way? Not likely they could detect that there is any intelligent life here. But if they had a program of sending beams of laser light in the direction of any possible habitable world in their vicinity - and had kept that up for thousands - or more likely hundreds of millions of years (still just a blink in geological time, so even that would be a remarkable coincidence that we look out for the signal within the same hundred million year long period that they were transmitting it) - then we would have a chance of spotting them.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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