Arecibo message Facts for Kids

"Arecibo Message" redirects here. For the 2009 Boxcutter album, see Arecibo Message (album).

This is the message with color added to highlight its parts. The message carried no color information.

The Arecibo message was a special radio message sent into space in 1974. It was sent to celebrate a big upgrade to the Arecibo radio telescope in Puerto Rico. This powerful message was aimed at a group of stars called M13. This group, known as a globular star cluster, is about 25,000 light years away from Earth. M13 was chosen because it was in the right place in the sky for the celebration.

Dr. Frank Drake, who created the famous Drake equation, wrote the message. He had help from other scientists, including Carl Sagan. The message was like a picture made of radio waves. It had seven main parts that showed information about humans and Earth.

The message included:

The numbers from one to ten.
The atomic numbers of important elements like hydrogen, carbon, nitrogen, oxygen, and phosphorus. These elements are the building blocks of DNA.
Formulas for the sugars and bases that make up DNA.
The number of nucleotides in DNA, and a picture of DNA's double helix shape.
A drawing of a human, their average size, and Earth's human population.
A map of our Solar System.
A picture of the Arecibo Observatory and the size of its giant antenna dish.

It will take 25,000 years for this message to reach the M13 star cluster. If anyone there sends a reply, it would take another 25,000 years to get back to us! This means the Arecibo message was not really a way to talk to extraterrestrial life. Instead, it was a way to show how amazing human technology was at the time. Cornell University, which built and ran the telescope, said the message's main goal was to show off the new equipment's power.

The message was made of 1679 binary digits, which is about 210 bytes of information. It was sent using radio waves at a frequency of 2380 MHz. The "ones" and "zeros" of the message were sent very quickly. The whole broadcast lasted less than three minutes.

The number 1679 was chosen because it is a special number. It can only be divided by 23 and 73. This allowed the message to be arranged into a rectangle of 73 rows by 23 columns. When decoded, this rectangle forms the image you see.

In 2009, a music group called Boxcutter released an album named Arecibo Message. It featured many short songs.

What the Message Showed
Arecibo Answer Crop Circle Hoax
See also

What the Message Showed

The Arecibo message was designed to be decoded as a picture. Each part of the picture shared important information about Earth and humans.

Numbers from One to Ten

Part 1 — The numbers from 1 to 10.

The first part of the message showed the numbers from 1 to 10. They were written in binary code, which uses only 0s and 1s. You would read them from top to bottom. The bottom row had markers to show where each number's code began.

Reading these numbers might not be easy for an alien! For the first seven numbers, you read three binary digits from top to bottom. For numbers 8, 9, and 10, the code spread across two columns. This was to show that bigger numbers could use more space.

DNA Elements

Part 2 — The elements constituting DNA.

This part of the message showed the atomic numbers of five important elements. These are hydrogen (H), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P). These elements are the basic ingredients that make up DNA.

Building Blocks of DNA

Part 3 — The nucleotides of DNA.

Next, the message described the chemical groups that form DNA. These are called nucleotides. They include a sugar called deoxyribose, phosphate, and four special nucleobases. The message showed the chemical formulas for these parts. It listed how many atoms of hydrogen, carbon, nitrogen, oxygen, and phosphorus were in each part. This was done in the same order as the elements listed before.

The DNA Double Helix

Part 4 — The DNA double helix structure.

This section showed a picture of the double helix shape of DNA. This is how DNA naturally looks. The vertical line in the middle was a binary number. It represented the number of base pairs in the human genome. In 1974, scientists thought there were about 4.3 billion base pairs. Today, we know there are closer to 3.2 billion base pairs in human DNA.

A Human Figure

Part 5 — Human form, the height and population of humans.

The middle of the message showed a simple drawing of a human. On the left side of the drawing, there was a binary number. This number, 14, was meant to be multiplied by the message's wavelength (126 millimeters). This calculation gave the average height of an adult human male: about 1.764 m (5 ft 9.4 in).

On the right side, another binary number showed the total human population on Earth in 1974. This was about 4.3 billion people. It's interesting that this number was very close to the estimated number of DNA base pairs at the time!

Our Solar System

Part 6 — The Sun and the planets.

This part of the message showed a picture of our Solar System. It included the Sun and the nine planets known at the time: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto is now called a dwarf planet.)

Earth, our planet, was shown a bit higher than the others. This was to show that the message came from Earth. The picture also gave a general idea of the size of each planet and the Sun, but it was not to scale.

The Arecibo Telescope

Part 7 — The Arecibo radio telescope.

The last part of the message was a picture of the Arecibo radio telescope itself. It also included a binary number representing the telescope's diameter. This number, 2,430, when multiplied by the message's wavelength (126 millimeters), gives the telescope's actual diameter: about 306.18 m (1,004 ft 6 in). The "M" shape in the image was there to show that the curved line was a concave, or bowl-shaped, mirror.

Arecibo Answer Crop Circle Hoax

The Arecibo reply was the name given to a crop circle that was made in the farmland next to the Chilbolton radio telescope in Hampshire, UK, on 19 August 2001. It was 75 feet wide and 120 feet long.

In 2001, a large crop circle appeared near the Chilbolton radio telescope in Hampshire, UK. People called it the "Arecibo answer" or "Chilbolton Code formation." This crop circle looked very similar to the Arecibo message. It had the same 23 by 73 grid.

However, there were some big differences. For example, in the section about chemical elements, silicon was added. The DNA diagram was also changed. The human figure was replaced with a drawing of a figure with a large, bulbous head. The solar system showed 9 planets, but it highlighted the 3rd, 4th, and 5th planets. The Arecibo telescope was replaced by a picture of another crop circle that had appeared in the same field a year before. The binary number for the transmitter's size was also different.

The SETI Institute, a group that searches for alien life, said that this crop circle was very likely made by humans. They stated there was no proof it came from aliens.

Arecibo message facts for kids

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