NASA's Voyager 2 probe, currently on a journeying toward interstellar space, has detected an growth inwards cosmic rays that originate exterior our solar system. Launched inwards 1977, Voyager 2 is a footling less than eleven billion miles (about 17.7 billion kilometers) from Earth, or to a greater extent than than 118 times the distance from footing to the Sun.
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| This graphic shows the pose of the Voyager 1 in addition to Voyager 2 probes relative to the heliosphere, a protective bubble created yesteryear the Dominicus that extends good yesteryear the orbit of Pluto. Voyager 1 crossed the heliopause, or the border of the heliosphere, inwards 2012. Voyager 2 is even in addition to hence inwards the heliosheath, or the outermost business office of the heliosphere [Credit: NASA/JPL-Caltech] |
Since belatedly August, the Cosmic Ray Subsystem musical instrument on Voyager 2 has measured almost a five percentage growth inwards the charge per unit of measurement of cosmic rays hitting the spacecraft compared to early on August. The probe's Low-Energy Charged Particle musical instrument has detected a similar growth inwards higher-energy cosmic rays.
Cosmic rays are fast-moving particles that originate exterior the solar system. Some of these cosmic rays are blocked yesteryear the heliosphere, in addition to hence mission planners await that Voyager 2 volition mensurate an growth inwards the charge per unit of measurement of cosmic rays every bit it approaches in addition to crosses the boundary of the heliosphere.
In May 2012, Voyager 1 experienced an growth inwards the charge per unit of measurement of cosmic rays similar to what Voyager 2 is immediately detecting. That was almost iii months earlier Voyager 1 crossed the heliopause in addition to entered interstellar space.
However, Voyager squad members annotation that the growth inwards cosmic rays is non a definitive sign that the probe is almost to cross the heliopause. Voyager 2 is inwards a unlike place inwards the heliosheath—the outer portion of the heliosphere—than Voyager 1 had been, in addition to possible differences inwards these locations agency Voyager 2 may sense a unlike go out timeline than Voyager 1.
The fact that Voyager 2 may go approaching the heliopause half-dozen years afterwards Voyager 1 is likewise relevant, because the heliopause moves inward in addition to outward during the Sun's 11-year action cycle. Solar action refers to emissions from the Sun, including solar flares in addition to eruptions of textile called coronal majority ejections. During the 11-year solar cycle, the Dominicus reaches both a maximum in addition to a minimum score of activity.
"We're seeing a alter inwards the surroundings around Voyager 2, there's no uncertainty almost that," said Voyager Project Scientist Ed Stone, based at Caltech inwards Pasadena. "We're going to larn a lot inwards the coming months, exactly nosotros even in addition to hence don't know when we'll attain the heliopause. We're non at that spot yet—that's ane affair I tin country amongst confidence."
Author: Karen Fox | Source: Jet Propulsion Laboratory [October 05, 2018]
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