Are we the only intelligent species in the universe? Astronomers have asked this question for decades, and for the most part, so has the human race.
Space is huge, with billions of stars in our galaxy alone. So, how do we narrow down where to listen? Well, researchers from the Max Planck Institute for Solar System Research (MPS) in Germany and from McMaster University in Canada may have come up with the solution.
NASA’s Kepler spacecraft has discovered more than 1,000 exoplanets. However, the search for extraterrestrial intelligence (SETI) has not been so successful. Does this mean that there are no extraterrestrials out there? Are really we alone?
Researchers René Heller and Ralph Pudritz believe the best chance we have to finding a signal would be to presume that any extraterrestrial observers would be using the same methods to search for us, that we are using to search for life in the universe.
Researchers on earth focus their search efforts on planets and moons that are too far away to see directly. So they have to study them by tracking their shadows as they pass in front of their own host stars, called transit.
A wealth of information can be collected by measuring the dimming of starlight as a planet crosses the face of its star during orbit, even without seeing these worlds directly.
In a paper published in the journal Astrobiology, Heller and Pudritz ask: “What if extraterrestrial observers discover the earth as it transits our sun?”
What should be done?
If our interstellar neighbors are using the same methods that we are using on earth, then it makes sense for humanity to turn its collective ear to earth’s “transit zone,” which is a small piece of the universe from which our planet’s path in front of the sun can be distinguished.
Heller said in a statement:
“It’s impossible to predict whether extraterrestrials use the same observational techniques as we do.
“But they will have to deal with the same physical principles as we do, and earth’s solar transits are an obvious method to detect us.”
There are approximately 100,000 potential targets within the transit zone. Each one has the potential to be orbited by habitable planets and moons, and that’s just the number we can see with today’s radio telescope technologies, say the researchers.
This narrows the area to look to about two thousandths of the entire sky. Heller said:
“The key point of this strategy is that it confines the search area to a very small part of the sky. As a consequence, it might take us less than a human life span to find out whether or not there are extraterrestrial astronomers who have found the earth.
“They may have detected earth’s biogenic atmosphere and started to contact whoever is home.”
Heller and Pudritz wrote in their study:
“If any of these planets host intelligent observers, they could have identified earth as a habitable, even as a living world long ago, and we could be receiving their broadcasts today.”
Heller and Pudritz believe that with efforts like the “Breakthrough Listen Initiative,” which is part of a $100 million project over 10 years, hunting for extraterrestrial life should be focused on the “transit zone.”
More about the Breakthrough Initiatives: