Have aliens noticed us? The possibility has been suggested

Enrico Fermi, back in 1950, proposed that any civilization with even a small degree of rocket technology could readily colonize the entire galaxy. He emphasized that given the Solar System is young in comparison to the universe's enormous 14 billion year history, "aliens should have already visited Earth" - as mentioned on the Space web portal.

Nevertheless, the Futurism portal suggests that scientists might be approaching research into alien civilizations from a skewed perspective. The emphasis is generally on our search for aliens, rather than considering whether Earth has already been spotted by them. "Some astronomers now propose that aliens might have already detected us, despite us being ignorant of their existence" – Futurism reports.

Howard Isaacson, an astronomer at the University of California in Berkeley, USA, asserts that Earth has transmitted signals affirming its presence for over a century. The most potent signals were sent between 1900 and World War II. –  They needed to be robust, considering the radio receivers at that time lacked sensitivity – Isaacson explains.

The situation has evolved since then. While Earth continues to emit numerous radio signals, these are less noticeable now. As expressed by Thomas Beatty, an astronomer at the University of Wisconsin, USA, Radio stations today focus on broadcasting towards Earth, rather than into space. However, this does not imply that Earth and humanity are currently going unnoticed by potential observers in the cosmos.

Many spacecraft are navigating the Solar System, including Voyager 1 (NASA), which is over 12 billion miles from Earth. Communication with such an object necessitates a powerful global antenna network. Isaacson's estimates suggest that some of these transmissions keep traveling even after they have bypassed their intended receiver in space, potentially received further in the universe.

In 2021, Jacqueline Faherty, an American astrophysicist, found that nearly 2,000 stars within a 300-light-year radius from Earth could observe the Earth's so-called transit. This phenomenon of our planet crossing in front of the Sun enables the detection of gases in the Earth's atmosphere. So, if an alien civilization receives a signal from Earth and thus learns of Earth's existence, it could remotely observe our planet and study factors like its composition.

Beatty points out that alien civilizations with advanced telescopes may discern the existence of human life on Earth. He adds that even with a less powerful telescope that merely depicts the Earth as a minute speck, alien observers might still deduce that our planet is inhabited.