Earth's high-altitude chorus waves, also known as "Earthsong," have struck a chord with NASA's SoundCloud listeners. (Image: NASA)
While the vacuum of space stifles sound waves, scientists still have ways of eavesdropping on the heavens. And after decades of collecting celestial sounds — from rocket launches and astronaut dialogue to alien lightning and interstellar plasma — the U.S. space agency recently set up a SoundCloud account, letting it stream a variety of eerie and iconic audio clips for anyone to hear.
NASA offers 63 sounds so far, including several of the most historic and mind-bending moments from the past half century of space exploration. Here are nine that deserve a few seconds of your time:
The most popular clip in NASA's SoundCloud feed is a noise produced by our own planet. Known as chorus, it's an electromagnetic phenomenon caused by plasma waves in Earth's radiation belts, which loom at least 8,000 miles above the surface. Although it's too high for humans to hear directly, ham radio operators have long detected it, especially in the morning. That has drawn comparisons to birdsongs, hence the nickname "Earthsong." NASA made this recording in 2012 with its EMFISIS probe.
Cassini began detecting Saturn's powerful radio emissions from more than 230 million miles away. (Image: NASA)
2. Saturn radio
Saturn is home to dramatic auroras, much like the northern and southern lights that dance around Earth's poles when solar wind hits the upper atmosphere. These lights are closely associated with the ringed planet's strong radio emissions, first detected by the Cassini spacecraft in 2002.
The Voyager 1 probe, now in interstellar space, has traveled farther than any spacecraft in history. (Image: NASA)
3. Interstellar plasma
Three decades after it left Earth, NASA's Voyager 1 has finally escaped the sun's magnetic field. NASA calls this clip "the sounds of interstellar space," since it represents data recorded outside the heliosphere in 2012 and 2013. And while those plasma waves wouldn't be audible to human ears, their frequency indicates denser gas in the interstellar medium — a big step in our journey beyond the solar system.
Jupiter's Great Red Spot, which dates back centuries, is the largest known storm in the solar system. (Image: NASA)
4. Lightning on Jupiter
The Voyager probes passed by Jupiter early in their journeys, offering an enlightening look at this stormy gas giant. The clip below features the "whistler" of a lightning strike on Jupiter, similar to whistling tones produced on Earth when lightning travels away from the planet into magnetized plasma overhead.
NASA's Kepler mission is meant to find potentially habitable planets orbiting stars in the Milky Way. (Image: NASA)
5. Sonified starlight
Finding patterns in data is often easier by ear, even if the data don't represent sounds. Scientists can "sonify" non-auditory data by translating its values to noises, much like a Geiger counter converts silent radiation to audible clicks. The technique can also shed light on faraway stars, as with this clip of sonified light waves from KIC 7671081B, a variable star listed in NASA's Kepler Input Catalog (KIC).
Towering plumes erupt from Enceladus, hinting at an ocean that scientists think lurks below its icy surface. (Image: NASA)
6. Eerie Enceladus
Enceladus, the sixth-largest of Saturn's several dozen moons, spews out gigantic plumes of water vapor from its ice-covered surface. The Cassini spacecraft detected a significant atmosphere around it in 2005, recording data from ion cyclotron waves represented in the audio clip below.
Sputnik measured just 22.8 inches wide and 184 pounds, but its historical significance was enormous. (Image: NASA)
7. A giant beep
Long before any of the sounds above were recorded, a satellite smaller than a basketball launched the space age in 1957 with an ominous beep. Named Sputnik, the Soviet spacecraft took 98 minutes to orbit Earth and quickly spurred the U.S.-U.S.S.R. space race. NASA was founded less than a year later.
Neil Armstrong's 1969 moonwalk made him the first of 12 people who have set foot on the lunar surface so far. (Image: NASA)
8. A giant leap
Of all the famous sounds in NASA's feed, few resonate like the first words of a human standing on the moon. Neil Armstrong may have left out the word "a" in his famous quote — since "man" and "mankind" otherwise mean the same thing in this context — but NASA adds it in parentheses for clarity.
NASA space shuttles flew 135 missions over 30 years, retiring in 2011 to make way for commercial spaceflight. (Image: NASA)
NASA has launched a lot of spacecraft during its first half century, several of which are now documented on SoundCloud with audio clips of countdowns, liftoffs, and communication between astronauts and mission controllers. The stream is full of historic highlights, but the clip below — from an April 2010 launch of the Discovery space shuttle — provides a good example of what it takes to leave the planet.
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- How to take clear photos of a light-polluted Milky Way