Using a computer model based on Voyager data, scientists have shown that the sun's magnetic field becomes bubbly in the heliosheath due to reconnection.
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Tone Tone Music Narrator: The two Voyager spacecraft have been traveling away from Earth for more than 33 years and they are finally in the outer edge of the solar system. This boundary is marked by the outer reaches of the sun's magnetic field and solar wind, which form an enormous expanse called the heliosphere. As the solar wind travels out from the sun, it pushes against the galactic medium and abruptly slows down. This is called the termination shock. Outside this is the heliosheath, where the solar wind slows to a stop and the magnetic field is bent back by the ionized interstellar wind. The sun's magnetic field spins opposite directions on the north and south poles, creating a sheet where the two spins meet. This sheet gently ripples as it travels outward and the ripples get bigger as they go. When this sheet reaches the termination shock, it starts to compress, like water waves hitting a wall. The Voyager spacecraft have now found that after the termination shock, these stacked-up ripples of magnetic field form bubbles, shown here as a computer simulation. This discovery has prompted a complete revision of what the heliosheath region looks like. The smooth streamlined look is gone, replaced with a bubbly, frothy outer layer. This new layer also changes our understanding of how extremely fast-moving particles called cosmic rays enter our solar system. When they arrive at the bubble region, they slowly move from bubble to bubble until they can reach smooth magnetic field lines and follow them toward the sun. The nature of the bubble region explains why Voyager II has been seeing variations in the number of energetic particles compared to Voyager I. Because of its path, Voyager II has been passing in and out of the bubble region. When it is in the region Voyager II sees many trapped cosmic rays and electrons. When it is out of the region the spacecraft sees fewer. Even as the Voyagers answer questions about our solar system, they raise others. For example, scientists aren't clear yet how the bubbly heliosheath is linked to the ribbon feature discovered by IBEX and Cassini. This ribbon shows the emission of energetic particles and seems to indicate some interaction with interstellar space. In the meantime, the Voyager spacecraft continue sending back data, and, after three decades, they still have a unique perspective to offer about the universe we live in. Beeping
