There may be co-orbital objects like asteroids up in space ideal for extraterrestrial intelligence (ETI) to observe the Earth, according to a new paper.

James Benford, who runs Microwave Sciences that creates high-power microwave systems, claims that there may be "lurkers" or alien eyes observing the Earth from a distance. According to him, near-Earth objects recently discovered could be an attractive spot for aliens to observe our planet while in a secure natural object.

Recently, plans to explore locations outside the solar system and other parts of the universe continue to materialize. There are even plans to investigate if interstellar journey could be possible soon. Amidst all of these initiatives, Benford claims that another civilization may be ahead of the race already. The co-orbital objects offer ETIs the resources they may need including concealment, firm anchor and other materials.

Benford did say that there are barely studies on these objects. Planetary radar observations or even SETI has not looked into them yet.

"I describe these objects found thus far and propose both passive and active observations of them as possible sites for ET probes," he said.

Benford usually works with his son Dominic Benford, a scientist at NASA, and his twin brother Gregory Benford, a noted science-fiction author for this Search for Extraterrestrial Intelligence or SETI, according to CNET.

This is not the first time that someone proposed the idea of an extraterrestrial spy satellite hiding near the Earth. In Ronald Bracewell's oft-referenced 1960 paper, he suggested that there could be alien civilizations monitoring "the progress of less advanced worlds and perhaps make contact at some point." He also said that aliens might have placed artificial intelligence in nearby planets.

Scientists who gathered during the Messaging Extraterrestrial Intelligence (METI) meeting on March 18 also talked about the possibility of Earth being under alien observation. During the meeting, around 60 scientists who study the possibility of communication with hypothetical intelligent extraterrestrials, discussed the "zoo hypothesis."

The hypothesis explains why aliens still haven't communicated with Earth, and that is because they have been observing from a distance, concealing their identity. These "galactic zookeepers" don't want to be found. It also seems unlikely that the Earth would be the only one with intelligent life given the number of planets in the galaxy.