With Pluto safely behind it, New Horizons is just hours away from passing a significant milestone: it would be 50 times further away from the Sun than Earth. The spacecraft completed a mission that had never been done before at the solar system's edge to mark the occasion.
New Horizons reached 50 astronomical units (AU) from the Sun at 8:42 EDT on Saturday, April 17. One AU is the average distance between Earth and the Sun. That's about 150 million kilometers.
This figure is entirely arbitrary and appealing to our base-10 sensibilities as a milestone. Still, it marks a significant achievement: New Horizons now joins an elite group of spacecraft that have traveled this distance, including Pioneers 10 and 11 and Voyagers 1 and 2. NASA said Voyager 1 is the farthest human-made spacecraft ever, orbiting the Sun at 152.5 AU, or 22.9 billion kilometers.
Currently exploring the Kuiper Belt beyond Pluto, New Horizons is just one of five spacecraft to reach 50 astronomical units – 50 times the distance between the Sun and Earth – on its way out of the solar system and, eventually, into interstellar space.
Wrap Your Head Around a Billion Miles Away
New Horizons was launched on January 19, 2006, and is now about 7.5 billion kilometers from Earth. Light takes seven hours to reach Earth at this wavelength, but sending orders to the probe and receiving a confirmation signal on Earth now takes 14 hours. Since the probe is so far away from Earth, Gizmodo Australia said the mission's view of distant stars differs from ours.
New Horizons' camera was pointed at the location in space where Voyager 1 is actually positioned as part of NASA's celebration.
"Never before has a spacecraft in the Kuiper Belt photographed the location of an even more distant spacecraft, now in interstellar space," declared NASA in a statement. "Although Voyager 1 is far too faint to be seen directly in the image, its location is known precisely due to NASA's radio tracking."
Alan Stern, the principal investigator for New Horizons at the Southwest Research Institute in Colorado, called it a "hauntingly beautiful picture." The image serves as a reminder that we are only in the early stages of being an alien civilization. Our scope into the universe is expanding every day.
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The mission's previous highlights include flybys of Jupiter in 2007 and Pluto in 2015, and a 2019 encounter with the strangely shaped Arrokoth.
The probe will resume its journey through the solar system's far reaches from here. The probe is also collecting valuable data about the solar wind and the space atmosphere throughout the mission's science process.
New Horizons' program will be upgraded later this year by NASA to improve its capability. The probe is supposed to last until the late 2030s when its nuclear battery will no longer keep up with the interstellar vehicle.
Is New Horizons Still In The Galaxy?
WRAL.com said New Horizons won't pass the heliopause, or the area of space where the solar winds from other stars are higher than the solar winds from our star, for another 25 years. But it's at the current speed of over 31,000 mph.
Both Voyager 1 and 2 were launched in the late 1970s, and about half of their instruments are now operational. These instruments verified that the probes had successfully entered outer space in 2012 and 2018.
Pioneer 10 and 11, which were launched in the early 1970s, are likely to be the next spacecraft to cross the interstellar benchmark, although the precise date remains unknown. Direct observations aren't feasible since no satellite has been heard from since 2003.
The Interstellar Boundary Explorer (IBEX) mission of NASA is determining not only how far out the Sun's impact reaches, but also the shape of the solar system as a result. The heliosphere is not a perfect globe, as the name implies.
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