Going… Going… Gone! Voyager I Enters Interstellar Space
Originally posted on Research & Collections:
About one year ago, I wrote a blog commemorating the 35th anniversary of the launch of Voyager I, the second of the twin Voyager spacecraft to be launched to deep space; Voyager II launched 16 days earlier. These amazing spacecraft — the fastest ever made — have been rocketing toward the end of the solar system at roughly 1 million miles per day for more than 35 years, and scientists have been eagerly awaiting signals of their departure from the edge of the solar system where solar wind and plasma have dominant influence (called the heliopause). Voyagers’ main mission was to explore the outer planets, which they did with great success, taking some of the first high-resolution images of the planets and their moons, and inspiring Carl Sagan to use Voyager I to take a photo of Earth from a distance of 3.7 billion miles, leading to his profound speech, “Pale Blue Dot.”
Now, scientists have announced with certainty that Voyager I has left the heliopause, the hypothesized boundary between the solar system and interstellar space (sometimes referred to as the interstellar medium). This is the first human-made object to enter the unchartered waters beyond the heliopause. To be clear, Voyager is both in interstellar space and in a region that is still governed by the Sun’s gravity — technically this is both interstellar space, and the solar system.