Launched in 1977, Voyager 1 overtook its twin, Voyager 2, as both explored the outer planets<\/p>\n
An artist’s concept depicts a NASA Voyager spacecraft travelling through interstellar space, in this image released on May 14, 2025. NASA\/JPL-Caltech\/Handout via REUTERS\u00a0 <\/p>\n
NASA’s Voyager 1<\/a> has already traveled farther than any other spacecraft from Earth<\/a> since its launch in 1977. The probe, which exited our solar system years ago \u200band is journeying through interstellar space, is now on the cusp of a remarkable milestone \u2014 traversing a light-day, the distance light travels in 24 hours.<\/p>\n A light-day is \u200cabout 16 billion miles (26 billion km). The US space agency said Voyager 1, flying at almost 38,000 miles per hour (61,000 kph) through the virtual vacuum of space, will reach that distance from Earth on Wednesday at 5:16 a.m. ET (1016 GMT). The robotic spacecraft has the distinction of being the most distant human-made object.<\/p>\n “I view it as an engineering milestone, marking the amazing longevity of Voyager 1 \u2014 and also an engineering achievement to be able to \u200bcommunicate with Voyager 1 at its distance,” said astrophysicist Alan Cummings, a senior research scientist in the Space Radiation Laboratory at Caltech who has been a Voyager program scientist \u200bsince 1973.<\/p>\n A light-year may be a more familiar concept for many people, a metric used for vast cosmic distances. It is the distance a \u2060particle of light, called a photon, travels in a year \u2014 about 5.9 trillion miles (9.5 trillion km). For instance, the closest stars beyond our solar system are the three that make up \u200bthe Alpha Centauri system, about 4.24 light-years away.<\/p>\n Twin spacecraft<\/strong><\/p>\n Voyager 1 and twin spacecraft Voyager 2 were launched 49 years ago, exploring planets in the outer solar system before continuing onward. Voyager 1 was \u200bcarried into space on September 5, 1977, atop a Titan IIIE-Centaur rocket from Cape Canaveral in Florida 16 days after the launch of Voyager 2, but overtook its twin within months.<\/p>\n “Voyager 1 returned a wealth of new information about Jupiter and Saturn, and their moons,” Cummings said.<\/p>\n It discovered a thin ring around Jupiter and two previously undetected Jovian moons, Thebe and Metis. It then spotted five new moons around Saturn as well as a \u200bring called the G-ring.<\/p>\n “Voyager 2 took a different path through the solar system after they launched in 1977, in order to visit Uranus and Neptune. Voyager 2 is on pace to be \u200bone light-day away from Earth in nine more years, in November 2035,” Cummings said.<\/p>\n Voyager 1 crossed the outer edge of the heliosphere, a protective bubble of particles and magnetic fields produced by the sun, and entered \u200cinterstellar space \u2060in 2012, continuing to collect data.<\/p>\n “It was the first spacecraft to report the energy spectra of galactic cosmic rays (fast-moving energetic particles) at low energies. Those energetic particles are not observable inside the heliosphere because of the push-back by the solar wind. This was the holy grail of low-energy cosmic ray physics,” said Cummings, an expert in cosmic rays.<\/p>\n Voyager 2 entered interstellar space in 2018<\/a>.<\/p>\n