Our beautiful green-blue third rock from the sun is very interesting to highly developed alien life forms. They may, of course, have honorable intentions, but when we look at our own history, voyages of discovery have usually been extremely tedious for the discovered indigenous peoples. Ask the Tasmanians but, at least the handful that are left. Should we hide from alien eyes? For the first time, a (relatively) practical method has now been devised.
The specialized satellite Kepler managed to increase the number of discovered exoplanets spectacularly. In fact, the principle of what Kepler does is simple: to constantly observe hundreds of thousands of stars in a segment of the sky. If a planet-sized object slides between the star and the satellite, this means a periodic, slight weakening of the star's light intensity. The odds of a planet's orbit moving exactly between the satellite and the star disk are slim - think one in a hundred or less. However, Kepler keeps an eye on hundreds of thousands of stars, so that on balance many planets are discovered.
What if aliens discover us?
Techniques we use to find interesting exoplanets can also be used by aliens to find us. If the Earth moves right between the sun and an alien observer, the sun's light is also dimmed and ET knows that there is a planet in the habitable zone around Sol. And so we can eventually expect visitors, say David M. Kipping and Alex Teachey of the Ivy League University of Columbia University.
How do we hide the earth?
Hiding a planet the size of Earth is far from easy at first glance. The solar energy covering the Earth is equal to the solar constant multiplied by the diameter of the Earth's shadow. We are talking about thousands of times the current energy consumption. Kipping and Teachey are now proposing to install a giant array of space lasers with a capacity of a large power plant: 250 MW. If we only mask the abnormal radiation that shows that there is life on earth, much less power is needed: around 160 kilowatts, the power of a heavy electric car. This for ten hours a year.
Is it smart?
Earth has been orbiting the sun for more than four billion years. Until now, to an alien observer, Earth was a low-profile planet around a low-profile star. An advanced alien civilization is likely to keep a close eye on the nearby cosmic environment, for obvious reasons. In short: aliens probably already know the earth and do not find our beloved marble interesting enough for a visit. Or they have already visited us in Von Däniken style, but then this discussion is pointless.
Presumably it will suddenly change the behavior of the earth by such cloak in our distant space brothers, make all tentacles twist in fascinating spasms. For example, think what the effects of the bizarre behavior on Earth this asterisk goods. They will then know that there is a technologically advanced species here on Earth, capable of disguising an entire planet. If the aliens are malicious or paranoid, chances are they will prepare an extremely unpleasant surprise for these nasty newcomers. That is why it is probably smarter to return our planet's radiation signature to a pre-industrial state.