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Pondering What’s Way, Way Out There

CAS astronomer uses Voyager probes to look beyond our solar system

| From BU Today | By Rich Barlow. Video by Devin Hahn and Joe Chan
Watch this video on YouTube

In the video above, Assistant Professor Merav Opher talks about the Voyager space probes.

And you thought the subway was slow. Merav Opher was all of seven when the twin Voyager probes launched into space during the Carter administration. It’s taken 34 years for them to reach the threshold of interstellar space, but they’ve made it. When Voyager 1 crosses the heliopause (the outer boundary of our sun’s magnetic field and winds), it will become the first human-made object to come in contact with “what lies beyond our solar system,” says Opher, telling us things never before known about far-flung space: What’s it made of? Is it hot, cold, dense…?

The image conjures poet and World War II aviator John Gillespie Magee’s line about having “slipped the surly bonds of earth…and touched the face of God.” Indeed, it was the poetry of scientific breakthroughs that led that seven-year-old to grow up to be an astronomer. Now a College of Arts & Sciences assistant professor of astronomy and a guest NASA investigator, Opher is among the stargazers waiting breathlessly for the precise moment Voyager crosses the heliopause.

No one is sure when that will be—sometime within the next one to three years, Opher says—but we know Voyager is close because it has detected solar winds at very low speeds, a sign that it’s in the neighborhood of the heliopause. Which is what makes Opher’s research so cutting-edge-of-the-solar-system.

When Voyager 1 crosses the heliopause, it will become the first human-made object to come in contact with “what lies beyond our solar system,” says Merav Opher, a College of Arts & Sciences assistant professor of astronomy. Photo by Melody Komyerov

The daughter of an astrophysicist, Opher, in a fit of youthful rebellion, once flirted with becoming a film director instead of a scientist. She changed course after a college professor “showed me how physics can be poetic, and this hooked me. I realized that physics can be as exciting as movies and opera!”

She and her NASA colleagues made news last summer when they announced that Voyager readings from 10 billion miles away indicate that the region between our solar system and interstellar space is a porous brew of massive magnetic “bubbles.” Contrary to previous belief, cosmic rays may be able to penetrate this boundary, the researchers said. There’s no radiation threat to humans, protected as we are by our planet’s atmosphere, but astronauts on NASA’s hoped-for Mars mission would need to beware of radiation leaking in from outside our solar system, according to the findings, because cosmic rays can damage DNA and immune systems.

The bubble theory needs further corroboration, Opher said at the time, but for now, it provides a plausible explanation as to why the Voyager probes have been experiencing wildly varying readings of the amount of electrons around them. A computer model based on the data suggested that huge magnetic bubbles, 100 million miles long and shaped like sausages, trap particles like electrons. As the probes enter a bubble, electron readings jump, falling again when the probes leave the bubble.

Seeking a simple simile for an interviewer, Opher likened that distant stretch of space to “a really agitated Jacuzzzi.” Chalk up another one for the poetry of science.

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