It could take 1,500 years before humans could make contact with alien species, scientists said.

"We haven't heard from aliens yet, as space is a big place. But that doesn't mean no one is out there," Evan Solomonides, a student from Cornell University who will be presenting the research paper, said in a news release.

"It's possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now," Solomonides said. "Until then, it is possible that we appear to be alone - even if we are not."

The research, which will be presented at the American Astronomical Society meeting in San Diego, California, is based on the Fermi Paradox described by physicist Enrico Fermi in 1950, which states that while billions of Earth-like planets exist in our galaxy, not one has made contact with Earth yet.

The Cornell researchers also paired their analysis with Copernicus' principle of mediocrity, which states that there is nothing special about the Earth's physical attributes, and so it could take a while before our planet could attract alien species.

Humans have been sending out broadcast signals into space for the past 80 years in hopes of finding life in another planet. According to NASA, signals have reached 2,326 confirmed exoplanets.

According to Solomonides, extraterrestrials could have received the signals from Earth. However, aliens would have found these signals undecipherable, and so they would need to decode the light waves into sounds and parse 3,000 human languages to understand the message.

However, according to David Kipping, assistant professor of astronomy at Colombia University who was not involved in the research, alien life is much broader than just radio and TV broadcast signals, and should include search for extraterrestrial artifacts.

"We don't have any evidence right now for extraterrestrial civilizations in the galaxy," he told FoxNews.com.

Kipping used the dimming star in the constellation Cygnus, which was initially believed to be an "alien megastructure," but only proved to be a result of camera and telescope changes.

While no one has tried to make contact with Earth yet, the scientists said that broadcast signals have reached every star within about 80 light years from the Sun - about 8,531 stars and 3,555 Earthlike planets, given that the Milky Way galaxy alone contains 200 billion stars.

"If we stop listening or looking, we may miss the signals. So we should keep looking," Solomonides said.