Earth’s Cosmic Address: How We Told the Universe Where We Are
Have you ever wondered where Earth is located in the vast universe?
We learn that Earth is spinning on its axis and orbiting the Sun, along with other planets. We also learn that our solar system is orbiting the centre of the Milky Way galaxy, which is one of billions of galaxies in the observable universe.
Some people might know that the Milky Way is also moving and will eventually collide and merge with the Andromeda galaxy, the nearest major galaxy to ours.
But don’t worry, this will happen in about four billion years. So, if all frames of reference are moving, not to mention that the universe is also expanding, then where is Earth?
I have been thinking about this question recently, and I think it is a good topic for a story.
It turns out that we have already tried to answer this question and communicate it to the rest of the cosmos. In the late 1970s, NASA sent two Voyager probes, which are now the farthest human-made objects from Earth.
They have both reached interstellar space, the region between stars where the galactic plasma is present. On board, each Voyager spacecraft is a time capsule: a 12-inch, gold-plated copper disk carrying spoken greetings in 55 languages from Earth’s peoples, along with 115 images and myriad sounds representing our home.
One of the diagrams engraved on the famous disk shows the location of Earth by referring to 14 pulsars and the centre of the galaxy. Pulsars are rapidly rotating neutron stars that emit beams of electromagnetic radiation. They can be used as cosmic clocks since their rotation periods are very stable and predictable.
The diagram shows the direction and distance of each pulsar from the Sun, as well as the frequency of their pulses. By comparing these values with the actual measurements of the pulsars, an extraterrestrial civilization could deduce the position and time of the Voyager spacecraft. The centre of the galaxy is also marked as a reference point since it is a prominent feature of the Milky Way.
The diagram was designed by Frank Drake, a pioneer of the search for extraterrestrial intelligence (SETI), with the help of Carl Sagan and other scientists. The scientist chose pulsars as the reference frame because they are long-lived, widely distributed, and easily detectable. They also avoided using any human or Earth-specific symbols, such as maps, coordinates, or units, to avoid confusion or misinterpretation.
The disk also contains other information about Earth and its inhabitants, such as sounds, images, greetings, and music. It is a message of peace and goodwill from humanity to the cosmos. You can learn more about the disk and its contents by visiting NASA/JPL Eyes. 🌎
It is possible that in the distant future, some civilization will discover the golden disk and decide to greet Earth because we have already given our location on the cosmic map.
Hopefully, they will be friendly visitors. Until then, we can marvel at the fact that we have sent a piece of ourselves into the unknown and wonder what else is out there.
Ad Astra🚀
RW
