Heading One / The recording starts with the patter of a summer squall. Later, a drifting.

Heading Two / The recording starts with the patter of a summer squall. Later, a drifting.

Heading Three / The recording starts with the patter of a summer squall. Later, a drifting.

Heading Four / The recording starts with the patter of a summer squall. Later, a drifting.

Heading Five / The recording starts with the patter of a summer squall. Later, a drifting.

Heading Six / The recording starts with the patter of a summer squall. Later, a drifting.

Large paragraph / The recording starts with the patter of a summer squall. Later, a drifting tone like that of a not-quite-tuned-in radio station rises and for a while drowns out the patter. These are the sounds encountered by NASA’s Cassini spacecraft as it dove through the gap between Saturn and its innermost ring on April 26, the first of 22 such encounters before it will plunge into Saturn’s atmosphere in September. What Cassini did not detect were many of the collisions of dust particles hitting the spacecraft as it passed through the plane of the rings. You can hear a couple of clicks,” said William S. Kurth, a research scientist at the University of Iowa who is the principal investigator for Cassini’s radio and plasma science instrument.

Normal Paragraph / The few dust hits that were recorded sounded like the small pops caused by dust on a LP record, he said. What he had expected was something more like the din of driving through Iowa in a hailstorm,” Dr. Kurth said. Since Cassini had not passed through this region before, scientists and engineers did not know for certain what it would encounter. Cassini would be traveling at more than 70,000 miles per hour as it passed within 2,000 miles of the cloud tops, and a chance hit with a sand grain could be trouble. The analysis indicated that the chances of such a collision were slim, but still risky enough that mission managers did not send Cassini here until the mission’s final months. As a better-safe-than-sorry precaution, the spacecraft was pointed with its big radio dish facing forward, like a shield. Not only was there nothing catastrophic, there was hardly anything at all. The few clicking sounds were generated by dust the size of cigarette smoke particles about a micron, or one-25,000th of an inch, in diameter.

Small Paragraph / To be clear: Cassini did not actually hear any sounds. It is, after all, flying through space where there is no air and thus no vibrating air molecules to convey sound waves. But space is full of radio waves, recorded by Dr. Kurth’s instrument, and those waves, just like the ones bouncing through the Earth’s atmosphere to broadcast the songs of Bruno Mars, Beyoncé and Taylor Swift, can be converted into audible sounds. Dr. Kurth said the background patter was likely oscillations of charged particles in the upper part of Saturn’s ionosphere where atoms are broken apart by solar and cosmic radiation. The louder tones were almost certainly whistler mode emissions” when the charged particles oscillate in unison. Mauna Loa, the biggest volcano on Earth — and one of the most active — covers half the Island of Hawaii. Just 35 miles to the northeast, Mauna Kea, known to native Hawaiians as Mauna a Wakea, rises nearly 14,000 feet above sea level. To them it represents a spiritual connection between our planet and the heavens above. These volcanoes, which have beguiled millions of tourists visiting the Hawaiian islands, have also plagued scientists with a long-running mystery: If they are so close together, how did they develop in two parallel tracks along the Hawaiian-Emperor chain formed over the same hot spot in the Pacific Ocean — and why are their chemical compositions so different?

• We knew this was related to something much deeper, but we couldn’t see what,” said Tim Jones, an earth science Ph.D. student at Australian National University and the lead author of a paper published in Nature on Wednesday that may hold the answer. Mr. Jones and his colleagues developed a model that simulates what’s happening in our planet’s mantle, beneath the crust that we live on, offering a window to the center of the Earth — or close to it.
• Their study may one day allow a reconstruction of the history of the movement of Earth’s plates — and the processes linked to these movements over billions of years, like mass extinction events, diamond and oil deposits, and changes in climate. If you were to drill nearly 4,000 miles into the Earth, you’d reach its core, a ball of solid iron surrounded by liquid that scientists estimate is hotter than the sun. Before making it there, you’d hit the mantle — an 1,800-mile-thick layer of solid rock that can flow like a liquid, just substantially slower. This mantle is the reason plates move across the surface. It’s why we have continents, earthquakes and volcanoes.
• The closest anyone ever got to the mantle was a seven-mile-deep hole drilled into the crust on a peninsula in western Russia. But now we can better understand what’s happening below by looking at Mauna Kea and Mauna Loa, said Mr. Jones. The prevailing hypothesis has been that volcanoes like these two in Hawaii are chemical fingerprints of the Earth’s composition at the deep mantle, just at the border of its core. Scientists have seismic evidence that the deep part of the mantle is a graveyard where long ago slabs of earth were subducted, or thrust underneath one another, creating separate regions with different chemical compositions that eventually made their way to the surface in a hot mantle plume, or upwelling, as the core heated the rock into magma.

1. We knew this was related to something much deeper, but we couldn’t see what,” said Tim Jones, an earth science Ph.D. student at Australian National University and the lead author of a paper published in Nature on Wednesday that may hold the answer. Mr. Jones and his colleagues developed a model that simulates what’s happening in our planet’s mantle, beneath the crust that we live on, offering a window to the center of the Earth — or close to it.
2. Their study may one day allow a reconstruction of the history of the movement of Earth’s plates — and the processes linked to these movements over billions of years, like mass extinction events, diamond and oil deposits, and changes in climate. If you were to drill nearly 4,000 miles into the Earth, you’d reach its core, a ball of solid iron surrounded by liquid that scientists estimate is hotter than the sun. Before making it there, you’d hit the mantle — an 1,800-mile-thick layer of solid rock that can flow like a liquid, just substantially slower. This mantle is the reason plates move across the surface. It’s why we have continents, earthquakes and volcanoes.
3. The closest anyone ever got to the mantle was a seven-mile-deep hole drilled into the crust on a peninsula in western Russia. But now we can better understand what’s happening below by looking at Mauna Kea and Mauna Loa, said Mr. Jones. The prevailing hypothesis has been that volcanoes like these two in Hawaii are chemical fingerprints of the Earth’s composition at the deep mantle, just at the border of its core. Scientists have seismic evidence that the deep part of the mantle is a graveyard where long ago slabs of earth were subducted, or thrust underneath one another, creating separate regions with different chemical compositions that eventually made their way to the surface in a hot mantle plume, or upwelling, as the core heated the rock into magma.