2/2: #Bestof2021: 2/2: The Voyager twins have departed: yet they can still communicate from interstellar space. Ken Croswell, The Lives of Stars.
The John Batchelor Show
John Batchelor
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🗓️ 8 March 2023
⏱️ 7 minutes
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2/2: #Bestof2021: 2/2: The Voyager twins have departed: yet they can still communicate from interstellar space. Ken Croswell, The Lives of Stars.
Proceedings of the National Academy of Sciences: https://www.pnas.org/content/118/17/e2106371118"The Sun helped confirm Voyager’s feat. Solar storms had erupted earlier in 2012, and the next year they shocked the plasma that Voyager 1 was speeding through, causing electrons there to oscillate and give off radio waves that the spacecraft detected. The frequency of those radio waves indicated that Voyager had indeed entered a much denser domain (2).
Voyager 1 thus became the first spacecraft ever to reach the interstellar medium. Contrary to some media reports, the craft had not left the solar system. Roughly a trillion icy bodies revolve around the Sun far beyond the orbits of Neptune and Pluto; every now and then one of them plunges toward the Sun and we see a new comet in the sky. The farthest of these distant icy objects are probably 1 to 2 light-years, or 63,000 to 126,000 astronomical units, away. Someone in the center of the continental United States who walks three miles west has gotten closer to the Pacific Ocean, relatively speaking, than Voyager has to the solar system’s edge.
On November 5, 2018, Voyager 2 also crossed the heliopause."
Transcript
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| 0:00.0 | This is CBSI in the world. I'm John Patchler. I'm speaking with Ken Croswell, Dr. Ken Croswell |
| 0:15.1 | and astronomer, who's writing at the proceedings of the National Academy of Sciences of the |
| 0:19.3 | United States of America about Voyager 1 and Voyager 2. Voyager 1 and Voyager 2 are now |
| 0:24.8 | in a place called the Helio Paws. My note says 121 astronomical units from the center of |
| 0:33.5 | our solar system. There are nowhere near the end of our solar system. However, Ken, I learned |
| 0:40.0 | from you that there was controversy here about how big the Helio Paws was and it was resolved |
| 0:45.1 | because of an event. Was it the event in 2012? The solar flares? Is that what did it? |
| 0:50.5 | Well, let me clarify some things here. The two voyagers have passed beyond the Helio Paws. |
| 0:57.8 | They're now in the interstellar medium. The Helio Paws is the edge of the Helio sphere, |
| 1:02.9 | which is the Sun's magnetic domain that it carved into the interstellar medium. Yes, |
| 1:08.6 | there were, I guess you could say, a couple controversies. The first was, well, we just said |
| 1:12.8 | no when the voyagers would cross into the interstellar medium. In the early 1990s, a scientist |
| 1:25.6 | at the University of Iowa, Don Grenette, had claimed that he had seen signs of the Helio Paws |
| 1:31.7 | in the far distance. A lot of people didn't want to hear that because they wanted the Helio Paws |
| 1:36.8 | to be a lot closer. They wanted to reach the interstellar medium sooner than what his estimate |
| 1:42.8 | set. He had placed the Helio Paws at a very large distance, but in the end, he turned out to be right. |
| 1:48.8 | In 2012, Voyager 1 did cross from the Helio sphere into the interstellar medium, crossing the Helio |
| 1:55.6 | Paws. There was, however, controversy at the time. In fact, there was so much controversy |
| 2:00.3 | that it took NASA 13 months to announce this major accomplishment. And for the reason was |
| 2:08.2 | one of the instruments on the spacecraft had stopped working, and that was an instrument that |
| 2:13.1 | measures the particle density. We expected that the particle density should increase |
| 2:18.9 | as you go from the outer parts of the Helio sphere into the interstellar medium. |
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