“Look again at that dot. That's here. That's home. That's us.”Carl Sagan used these words to describe the Pale Blue Dot image in his book ‘Pale Blue Dot: A Vision of the Human Future in Space’. Captured by Voyager 1, a spacecraft carrying messages from humanity, the image offers a striking portrait of Earth.
Voyager 1 is now set to make history as the farthest human-made object in space.
Nearly 50 years after its launch on September 5, 1977, Voyager 1 will reach one light-day from Earth on November 18, 2026, at 5:16:07 am EST. NASA is conducting a ‘Shine Bright for Voyager’s Light-Day’ event to celebrate this extraordinary milestone.
On November 17, millions of people around the world are encouraged to take part in the event by flashing ‘VGR’ in Morse code with NASA’s automated flasher or a flashlight. NASA has also asked people to share recordings of themselves participating in the event on social media, tagging NASA. And on November 19, NASA’s Jet Propulsion Laboratory (JPL) will conduct a discussion and Q&A about Voyager 1 and 2 and provide an update on their current status.
To understand why Voyager 1’s one light-day milestone is such a significant achievement for NASA, it is important to first understand what a light-day means.
In an age of high-speed internet, we’re used to messages arriving in seconds. But imagine sending a message to a spacecraft and waiting 24 hours for it to arrive. That’s how long a message takes to reach Voyager 1.
To put that distance in perspective, let’s consider how long light takes to travel to a few celestial objects. The Moon is about 2,38,855 miles from Earth, yet light reaches it in just 1.3 seconds. The Sun is about 93 million miles away, and its light takes about eight minutes to reach Earth. Neptune, roughly 2.8 billion miles away, is about four light-hours from Earth.
Voyager 1 is currently about 16 billion miles from Earth. It takes roughly 24 hours for a message to travel from Earth to the spacecraft, and another 24 hours for a reply to return. That is what it means to be one light-day away.
In 2012, Voyager 1 entered interstellar space and continued its journey towards the unknown.
Voyager 1 and its twin probe, Voyager 2, are travelling through the vastness of space, carrying messages from humanity. Each spacecraft carries a phonograph record, a 12-inch, gold-plated copper disk known as the Golden Record, encased in a protective aluminum jacket. The package also includes a cartridge, a needle, and instructions explaining the spacecraft’s origins and how to play the record.
“The spacecraft will be encountered, and the record played only if there are advanced spacefaring civilizations in interstellar space”, says Carl Sagan, who chaired the committee that selected the record’s contents.
The record includes greetings in 55 languages from around the world (including more than 10 Indian languages), various natural sounds from Earth, a 90-minute selection of music from different parts of the world, 115 images encoded in analog form, and printed messages from President Carter and UN Secretary-General Waldheim.
There is something poetic about knowing that, long after we are gone, proof of our existence will still be traveling through the vastness of space, waiting to be discovered by intelligent life, perhaps someday.
The Golden Record, curated over months and carrying a carefully considered portrait of humanity, left Earth in 1977. On November 18, as Voyager 1 reaches the one-light-day milestone, NASA will capture millions of people flashing the Morse code ‘VGR’ on their smartphones. One message is permanent but frozen; the other, fleeting but participatory.
Although Voyager 1 was launched after Voyager 2, it followed a faster trajectory, crossed the asteroid belt first, and is now travelling through interstellar space beyond the heliopause.
But where exactly is this spacecraft carrying humanity’s message going?
About 17 light-years from Earth, in the constellation Ursa Minor, lies the relatively obscure star Gliese 445 (AC +79 3888). Voyager 1 is headed in its direction and is expected to pass within about 1.7 light-years of the star in roughly 40,000 years.
That is a long time compared with the brief span of a human life. Voyager 1 may even fall silent before it reaches nearby Gliese 445, but that is a story for the future. For now, what matters is the certainty that it will reach a distance of one light-day on November 18, 2026, an extraordinary milestone for any human-made object.
(With inputs from NASA/JPL-Caltech)