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This Is What Space Sounds Like

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While it may be true that in space no one can hear you scream, that doesn’t necessarily mean the universe is completely silent. Recordings released by NASA in the early '90s show just how noisy space can be if you know how to listen.

In 1977, NASA launched Voyagers 1 and 2 into the vacuum of space in hopes of studying the outer planets of our solar system. Traveling at about 30,000 miles per hour, these probes have traversed billions of miles since their launch, all while sending home vast amounts of information and images of some of our more distant neighbors, including Jupiter, Saturn, Neptune, and Uranus. On August 25, 2012, Voyager 1 became the first human-made object to leave our solar system, and it still manages to send back vital information in messages that take over 17 hours to reach Earth.

Voyager 1 may have to wait about another 40,000 years to approach another star, but that may be a relief to the probe, because our neighbors never shut up. There may be no mechanical noise—sound that requires a medium such as a solid, liquid, or gas to resonate through—in space, but electromagnetic waves have no problem traveling through a vacuum. As they passed by the outer planets, Voyagers 1 and 2 recorded this wave data as solar wind clashed with the planets’ magnetospheres. The probes also managed to listen in on atmospheric radio waves, charged particle interactions, and even some particle emissions from places like Saturn’s rings, then relay all of this data back home.

Electromagnetic waves can’t be heard in their raw form, but that doesn’t mean they can’t be converted into something audible. Just as radio waves can be translated into the sound of morning FM talk show hosts, the Voyager data streams can be converted into audio, thereby letting humans listen in on interplanetary conversations. And, as it turns out, these conversations are riveting. 

In 1992, NASA released a series of these recordings entitled Symphonies of the Planets. The tracks are beautifully haunting in a way that rivals anything experimental electronic artists make. The collection’s echoing siren sounds manage to give the listener a sense of just how vast and complex our universe is, as well as how amazing an achievement the Voyagers are. Unfortunately, due to some cosmic injustice, the albums are no longer in print, but just like the electromagnetic waves, there are ways to still listen to them. Copies now exist on YouTube and streaming services like Spotify. Go ahead and give them a listen, and try not to get misty-eyed while hearing what the Voyagers heard as they hurtled onward into a vast, quiet universe. Well, relatively quiet.

See also: What Does Space Smell Like?

What Solar Eclipses Look Like on Different Planets
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Triple solar eclipse on Jupiter.

On Monday, August 21, North America will be treated to dazzling views of a total solar eclipse. But what if humans lived someplace else in the solar system—would eclipses be regarded with the same excitement and awe as they are here on Earth?

In her new video, Physics Girl Dianna Cowern investigates what these celestial events look like beyond our home planet. She discovers that, on some planets, total solar eclipses aren't even possible. The two moons orbiting Mars, for example, are too small to completely block the Sun. Move on to other parts of the solar system and you'll find places where total eclipses aren't rare at all. On Jupiter, which has 69 moons, it's possible for there to be multiple eclipses occurring at the same time. On Pluto, whose moon appears much larger in its sky than the Sun, total eclipses can happen every day for years on end.

Considering all the factors required to make a perfect solar eclipse, we're pretty lucky to be able to see one from Earth at all. And if you're close enough to the path of totality to view this year's North American eclipse, you can consider yourself even luckier.

[h/t Physics Girl]

Big Questions
What is Mercury in Retrograde, and Why Do We Blame Things On It?
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Mercury passing the Sun.

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the third time this year on Sunday, August 13 (or August 12, depending on where you live). But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?


Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.


Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."


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