Navigating ‘out there’ misconceptions about space

Opinion

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This article was published 05/01/2019 (2461 days ago), so information in it may no longer be current.

Space is literally all around us, but it’s notoriously difficult to wrap our minds around it. Given the hundreds of billions of stars and planets that make up our galaxy alone, who can be blamed for a lack of cosmic perspective, even if NASA’s InSight explorer just landed on Mars to send some back? As an astronomer at the Adler Planetarium in Chicago, I spend a lot of time talking with visitors about their space questions, as well as debunking some persistent misconceptions. These five crop up again and again.

Myth No. 1: There’s no gravity in space.

Maybe you’ve seen those videos of weightless astronauts on the International Space Station, gracefully (or sometimes not so gracefully) flipping and floating around, hair aloft, like swimmers in a starry sea. This often leads people to conclude that there’s no gravity up there. “Gravity is an important influence on root growth, but the scientists found that their space plants didn’t need it to flourish,” National Geographic wrote in 2012 of botanical research aboard the space station.

In fact, if there were no gravity in space, it wouldn’t be possible for astronauts (or anything) to orbit the Earth. As Newton explained it, gravity is the mutual attraction between any objects that have mass. When a rocket is in space, the vehicle and the astronauts carried by it still feel the pull of the planet’s gravity. No matter where they are, they have some gravitational relationship with objects — from distant planets to faraway stars — however faint it might be. You, too, experience the tug of the entire universe, even if the tug that you notice is from Earth.

Myth No. 2: Black holes suck.

News outlets tend to describe these gravity wells as if they were oversize cosmic vacuums. “Black hole sucks down star stuff at 30 per cent speed of light,” proclaimed a recent Discover magazine headline. The website Futurism offered a survival guide for those who somehow “get sucked into a black hole.”

In truth, black holes are a bunch of mass crunched together into a tiny volume, creating a huge gravitational field. Where their gravitational field is strongest, not even light, the fastest thing in the universe, can escape. As a result, black holes have been hard for astronomers to study, since most of our understanding of the universe relies on measuring light.

What we do know is that the huge masses of black holes (anywhere from tens to millions of times the mass of our sun) bend space-time in extreme ways, which is why illustrations often make them look like deep cosmic funnels. If you get close enough to one, you will certainly experience its powerful gravitational force, which is why astronomers see stars orbiting the supermassive black hole at the center of our Milky Way galaxy. But the gravitational tug is just like that of any other object — dependent on mass and distance — and it’s not special just because it’s caused by a black hole.

Myth No. 3: The sun is yellow.

Every child has reached for the yellow crayon when it’s time to draw the sun. This perception leads to articles such as one from Sciworthy that begins, “The yellow sun in our sky provides the light and energy needed to sustain our planet.” Pretty forgivable, given that astronomers refer to the sun as a “yellow dwarf.”

Yet to understand the true colour of the sun, you have to know a little bit about light itself. Visible light, the kind that human eyes can see, is just a tiny fraction of the energies of light in the universe. Mixed together, all this light appears white — but the colours of the rainbow, from red to violet, are different energies of light that your eyes can see. By the time light from the sun hits your eyes, it has travelled across the solar system and through Earth’s atmosphere, which bends, filters and scatters solar radiation before it makes it to our eyes. Because the higher-energy, bluer light gets scattered more, the light from the sun that reaches our eyes on Earth appears more yellow. But in space, the sun would appear white to us.

Myth No. 4: The sun is on fire.

As it turns out, when you take the incredibly dynamic surface of the sun and colourize it in yellows and oranges, it looks a whole lot like fire. Astronomers speak of the sun “burning” hydrogen, and Popular Science writes that we’re lucky “it didn’t burn out before we showed up a few hundred thousand years ago.”

In the case of our sun, however, “burning” is a misnomer. There is no combustion, fed by oxygen, to release the energy stored in the fuel. Stars generate energy through fusion, smashing together atoms deep in their cores like gigantic particle colliders. These fusion reactions take lighter elements, such as hydrogen, and smash them together to build heavier elements (like helium). When hydrogen atoms fuse together, they release energy, which eventually makes it out of the heart of the star to shine into the universe.

Myth No. 5: It would be hard to fly through the asteroid belt.

To get past Mars, onward to Jupiter and beyond, one must pass through the asteroid belt, a region of space that harbours an especially large number of rocks. That sounds dangerous, at least to some science fans who write into sites like “Ask an Astronomer.” Usually, people’s ideas about the asteroid belt come from scenes in sci-fi movies such as The Empire Strikes Back, in which Han Solo nimbly navigates the Millennium Falcon through a dangerous field strewn with jagged, flying boulders.

In reality, we’ve successfully sent numerous NASA missions to study the outer solar system, no bobbing or weaving required. At the extreme speeds they travel, spacecraft don’t need to hit a boulder to be annihilated. Navigating the asteroid belt in our solar system, however, is a piece of cake. While it does have a lot of rocks flying around in it compared with other regions of space, those rocks are hundreds of thousands of miles apart, on average.

Lucianne Walkowicz is an astronomer at the Adler Planetarium, and the 5th Blumberg Chair in Astrobiology at the Library of Congress.

— Washington Post