Hello, Aliens?

On November 16, 1974, scientists beamed a message into outer space from a giant telescope at the Arecibo Observatory in Puerto Rico. For three minutes, the telescope aimed bursts of radio waves toward a cluster of stars more than 25,000 light-years away. A light-year is the distance that light travels in one year: 9.5 trillion kilometers (5.9 trillion miles). This transmission, known as the Arecibo message, was humanity’s first attempt to contact aliens in another solar system.

The Arecibo radio telescope was originally designed to detect signals from space. In 1974, it was upgraded to broadcast information as well—making it the perfect device to send a message to the stars. “Radio waves cut through the cosmic static of interstellar space and travel at the speed of light, making communication as efficient and rapid as possible,” explains Douglas Vakoch. He’s the president of Messaging Extraterrestrial Intelligence (METI) International, an organization that transmits messages to try to communicate with civilizations on other worlds.

The Arecibo transmission carried a simple message written in binary code—a string of 1’s and 0’s that can represent letters, numbers, or other characters. When put together, the code created a series of pictures. They included a human being, a diagram of our solar system, and a strand of the molecule DNA—which holds the blueprint for human life as we know it (see The Arecibo Message: Decoded).

Now, nearly 50 years later, a team of researchers from around the world wants to update the iconic message—and increase its chances of being detected by extraterrestrials.

On November 16, 1974, scientists beamed a message into outer space. It came from a giant telescope at the Arecibo Observatory in Puerto Rico. For three minutes, the telescope aimed bursts of radio waves toward a cluster of stars. They were more than 25,000 light-years away. A light-year is the distance that light travels in one year: 9.5 trillion kilometers (5.9 trillion miles). This transmission is known as the Arecibo message. It was humanity’s first attempt to contact aliens in another solar system.

The Arecibo radio telescope was built to detect signals from space. In 1974, it was upgraded to send out information too. It was the perfect tool for sending a message to the stars. “Radio waves cut through the cosmic static of interstellar space and travel at the speed of light, making communication as efficient and rapid as possible,” explains Douglas Vakoch. He’s the president of Messaging Extraterrestrial Intelligence (METI) International. That’s an organization that tries to communicate with civilizations on other worlds.

The Arecibo transmission carried a simple message written in binary code. This code is a string of 1’s and 0’s. They can represent letters, numbers, or other symbols. When put together, the code made a series of pictures. They included a human being, a diagram of our solar system, and a strand of the molecule DNA. It holds the blueprint for human life as we know it (see The Arecibo Message: Decoded).

Now, nearly 50 years later, a team of researchers from around the world wants to update the classic message. They also want to increase its chances of being detected by extraterrestrials.

For decades, humans have been sending messages to outer space. Some messages, like the Arecibo message, were broadcast as radio transmissions. Others were carried aboard physical objects (see Space Jams). But it’s unlikely that aliens will ever encounter these past communications. “The Milky Way galaxy is big,” says Jonathan Jiang, an astronomer at NASA’s Jet Propulsion Laboratory in California. When the Arecibo transmission was sent, scientists didn’t have enough knowledge of the universe to determine where alien life was most likely to exist.

In the 1970s, the only known planets were those in our solar system. But in the past 30 years, scientists have discovered more than 5,000 exoplanets, or planets outside our solar system. About 5 percent of these planets occupy a habitable zone—the distance from a star at which liquid water can form, which is thought to be necessary for life.

For decades, humans have been sending messages to outer space. Some messages, like the Arecibo message, were broadcast as radio transmissions. Others were carried on physical objects (see Space Jams). But aliens will probably never find these old messages. “The Milky Way galaxy is big,” says Jonathan Jiang. He’s an astronomer at NASA’s Jet Propulsion Laboratory in California. When the Arecibo transmission was sent, scientists didn’t have much knowledge about where alien life was most likely to be. 

In the 1970s, the only known planets were those in our solar system. But in the past 30 years, scientists have discovered more than 5,000 exoplanets. These are planets outside our solar system. About 5 percent of these planets are in a habitable zone. That means they’re at the distance from a star at which liquid water can form. It’s thought to be necessary for life. 

In 2021, Jiang worked on a study that calculated where in the galaxy an alien civilization was most likely to develop: a group of millions of stars in the Milky Way about 10,000 to 20,000 light-years from Earth. Sending a radio message to this location could improve the chances it will be received.

Jiang, who was a kid when the Arecibo transmission was sent, also realized that its message could be improved and updated. So Jiang and a group of scientists came together to revise the message.

In 2021, Jiang helped calculate where in our galaxy an alien civilization was most likely to form. He thought it would be in a group of millions of stars in the Milky Way. These stars are about 10,000 to 20,000 light-years from Earth. Sending a radio message there could boost the chances it will be received. 

Jiang was a kid when the Arecibo transmission was sent. He realized that its message could be improved and updated. So Jiang and a group of scientists came together to revise the message.

Jiang and his team started brainstorming what their message should include. They decided to try to pack the maximum amount of information into the shortest possible message. Ultimately, their updated message, dubbed the “Beacon in the Galaxy,” contains 121 times as much data as the original Arecibo message. It includes a map of Earth and its location in the universe, information about its structure and composition, and more detailed human figures. It also contains an invitation for aliens to reply.

Like the Arecibo message, the Beacon in the Galaxy will be made of binary-coded radio bursts. “Aliens won’t speak English or Mandarin or Swahili,” says Vakoch of METI. “We have to find a common language—the basic principles of math and science.”

Jiang and his team started brainstorming what should be in their message. They wanted to pack a lot of information into a short message. Their new message is called the “Beacon in the Galaxy.” It contains 121 times as much data as the original Arecibo message. It includes a map of Earth and its location in the universe and information about its structure and composition. It has more detailed human figures. It also contains an invitation for aliens to reply.

Like the Arecibo message, the Beacon in the Galaxy will be made of binary-coded radio bursts. “Aliens won’t speak English or Mandarin or Swahili,” says Vakoch of METI. “We have to find a common language—the basic principles of math and science.”

Before the team can send out their updated message, they’ll need to find a way to broadcast it. That’s because the telescope at the Arecibo Observatory suffered structural damage and collapsed in 2020. Scientists would need to modify another large telescope to make the transmission. The team already has potential telescope options in mind. But first, they want to share their message with the public. “We are not planning to send this out until everybody agrees,” says Jiang. “We want to encourage an open discussion and remind people that they are all citizens of Earth.”

Not everyone is excited about trying to communicate with aliens. “Some people think it is dangerous to give aliens information about our existence,” says Chris Impey, an astronomer at the University of Arizona. What if the aliens we contact aren’t peaceful? Some believe “it’s safer to just listen for signals from a distant civilization and then decide whether to reply,” Impey says.

But like it or not, we’ve already been broadcasting our presence for more than a century—ever since radio was invented. “Any civilization capable of traveling to Earth can already pick up those accidental TV and radio signals,” says Vakoch. “Sending intentional signals into space doesn’t increase the risk of extraterrestrials knowing we’re here—it just lets them know we want to start a conversation.”

Still, this conversation probably won’t take place anytime soon. The Arecibo message, for example, won’t arrive at its target for another 25,000 years. And if any aliens happen to detect that message, decode it, and send a reply, it would take thousands of years for their response to get back to Earth.

So far, scientists haven’t found any signs of alien life—peaceful or otherwise. But that doesn’t mean there isn’t life out there. The universe is big, after all. “It’s a great question: ‘Are we alone?’ We don’t know yet,” says Jiang. “Maybe our children, or our children’s children, will make that discovery.” Until then, scientists will continue to watch the skies.

telescope at the Arecibo Observatory was damaged. It collapsed in 2020. Scientists would need to modify another large telescope to make the transmission. The team already has a few telescope options in mind. But first, they want to share their message with the public. “We are not planning to send this out until everybody agrees,” says Jiang. “We want to encourage an open discussion and remind people that they are all citizens of Earth.”

Not everyone wants to communicate with aliens. “Some people think it is dangerous to give aliens information about our existence,” says Chris Impey, an astronomer at the University of Arizona. What if the aliens we contact aren’t peaceful? Some believe “it’s safer to just listen for signals from a distant civilization and then decide whether to reply,” Impey says.

But we’ve already been broadcasting our presence for more than a century. It’s been happening ever since radio was invented. “Any civilization capable of traveling to Earth can already pick up those accidental TV and radio signals,” says Vakoch. “Sending intentional signals into space doesn’t increase the risk of extraterrestrials knowing we’re here—it just lets them know we want to start a conversation.”

This conversation probably won’t take place anytime soon. The original Arecibo message won’t arrive at its target for another 25,000 years. Say some aliens happen to detect that message, decode it, and answer. It would take thousands of years for their reply to get back to Earth.

So far, scientists haven’t found any signs of alien life—peaceful or otherwise. But that doesn’t mean there isn’t life out there. The universe is big, after all. “It’s a great question: ‘Are we alone?’ We don’t know yet,” says Jiang. “Maybe our children, or our children’s children, will make that discovery.” Until then, scientists will continue to watch the skies.