10 Misconceptions About Space

People have a lot of weird misconceptions about space (thanks, Hollywood). Here are a few myths about the universe and their real explanations—and we hope you like NASA, because they're going to come up a lot.

1. The Sun is on fire.

Artist's rendering of the sun

When some people picture the Sun, they imagine something like a campfire or an object on fire. But the Sun is actually a ball of gas. It burns thanks to nuclear fusion, which happens in its core. Every second, 700 million tons of hydrogen gets converted into 695 million tons of helium. When this happens, energy is released as gamma rays, which get converted to light. So, the Sun emits light and heat, but it's not on fire, because there's no oxygen involved.

2. The Sun is the only star that has planets.

Jupiter and Mars in the solar system

Experts now believe that most of the stars in our Milky Way have planets surrounding them. Any planet that's found outside of our solar system is known as an exoplanet, and we can be pretty sure that they exist because they affect the way a star appears. One of the most common ways to detect exoplanets is to look for a decrease in light from certain stars at various times, which would indicate that a planet is passing in front of the star, affecting how the light appears to us.

3. Mercury is the closest planet to the Sun, so it's the hottest.

Colorized image of Venus's clouds
NASA/JPL // Public Domain

Distance from the Sun actually has little to do with the average temperature on a planet. Venus (the second planet from the Sun) is the hottest planet in the solar system, but that's because of its atmosphere, which contains mostly carbon dioxide and some nitrogen, making it very thick. Throughout the year the surface of Venus remains at a temperature of about 462°C. The surface of Mercury, on the other hand, has a lot of temperature variations. It can be as cold as -173°C at night, and during the day it might reach 427°C. Mercury has a very thin atmosphere, which is why there's so much variation in temperature.

4. People explode in space.

NASA astronaut performing a spacewalk
NASA/JSC // Public Domain

Space is a near-vacuum, which means that people can't survive out there for more than a few minutes—but exploding isn't a concern. A body exposed in space will expand and bloat, especially the air in the lungs and the water in body tissue, but human skin is actually tight enough to prevent exploding. A person exposed to space would eventually die when circulation stops, after dissolved gases in the blood form bubbles and block flow. Basically, it's like an extreme version of "the bends" that divers can get.

5. In the 1960s, NASA spent millions developing a pen that would write in space.

NASA astronaut writing with a space pen
NASA/JSC // Public Domain

This is a popular myth on the internet—and even in one episode of The West Wing. People tend to use this as a comparison between NASA and Soviet astronauts, who were smart enough to just bring pencils. But NASA used pencils as well, and they have the receipts to prove it. In 1965, NASA placed an order for 34 mechanical pencils from Houston's Tycam Engineering Manufacturing Incorporated. There was an independent company, the Fisher Pen Company, that developed a space pen for around $1 million. And later, both NASA and the Soviets started using Fisher's anti-gravity space pen (it was a great pen).

6. In space, you experience zero gravity.

NASA astronauts experiencing decreased gravity
NASA/JSC // Public Domain">NASA/JSC // Public Domain

Gravity is considered the most important force in the universe, and it doesn't just go away when we leave Earth. Gravity is necessary for everything from the Moon's ability to orbit the Earth to the Sun staying put in the Milky Way. What astronauts actually experience in space is what NASA calls micro-gravity. It has nothing to do with the actual strength of gravity, which is only very slightly less on the International Space Station. It's because astronauts are constantly falling, so they seem weightless.

7. Black holes are like vacuums.

As we learn more and more about black holes, experts are more likely to compare them to Venus flytraps than vacuums. Black holes don't suck up everything nearby; instead, they sit pretty dormant, then if a star approaches it and gets too close, the black hole becomes active. And still, only some of the objects nearby get ripped apart by the black hole.

8. The Moon orbits Earth once a day.

Earth's moon
NASA/JPL/USGS // Public Domain

It takes about 27.3 days for the Moon to orbit Earth. This is known as a sidereal month. It's worth noting that the Moon's orbit isn't considered regular—it has variations, and there are upwards of five different months that astronomers recognize.

9. There's a dark side of the Moon.

Earth's Moon from the International Space Station
NASA/JSC // Public Domain

As the Moon is orbiting Earth, it's also rotating on its axis, so we're always seeing the same side of the Moon. But the opposite side isn't dark: it gets the same amount of sunlight as the other side.

10. A light-year measures time.

It actually measures distance. NASA defines a light-year as "the total distance that a beam of light, moving in a straight line, travels in one year." Light travels at around 300,000 kilometers per second, so a light-year is around 10 trillion (10,000,000,000,000) kilometers.

Be sure to subscribe here for more Mental Floss videos.

This story was republished in 2019.

How to See the Full Sturgeon Moon on Thursday

Brook Mitchell, Stringer/Getty Images
Brook Mitchell, Stringer/Getty Images

The full moon of every month has a special nickname. Some—like September's harvest moon, December's cold moon, and May's flower moon—have obvious connections to their seasons, while other names are harder to decode. August's sturgeon moon is an example of the latter. It may not be the prettiest lunar title in The Old Farmer's Almanac, but that doesn't mean the event itself on August 15, 2019 won't be a spectacular sight to behold.

What is a Full Sturgeon Moon?

The first (and normally the only) full moon that occurs in August is called a sturgeon moon. The name may have originated with Native American tribes living around the Great Lakes in the Midwest and Lake Champlain in New England. These bodies of water contain lake sturgeon, a species of freshwater fish that grows up to 6.5 feet in length and can live 55 years or longer. August's full moon was dubbed the sturgeon moon to reflect its harvesting season. This full moon is sometimes called the green corn moon, the grain moon, and the blackberry moon for similar reasons.

When to See the Full Sturgeon Moon

On Thursday, August 15, the full sturgeon moon will be highly visible around sunrise and sunset. The satellite will be 99.9 percent illuminated by the sun when it sets Thursday morning at 5:57 a.m EDT—just nine minutes before dawn. On the West Coast, the setting moon will coincide perfectly with the rising sun at 6:15 a.m. PDT.

If you aren't interested in getting out of bed early to catch the sturgeon moon, wait until Thursday evening to look to the horizon. Twenty-seven minutes after sunset, the full moon will rise on the East Coast at 8:21 p.m. EDT. On the West Coast it rises at 8:10 p.m. PDT, 30 minutes after the sun sets.

The moon generally looks bigger and brighter when it's near the horizon, so twilight and dawn are ideal times to catch the spectacle. But it's worth taking another peek at the sky closer to midnight Thursday night; the Perseid meteor shower is currently active, and though the light of the moon may wash them out, you're most likely to spot a shooting star in the late night and early morning hours.

A Full Harvest Moon Is Coming in September

suerob/iStock via Getty Images
suerob/iStock via Getty Images

The Old Farmer's Almanac lists a special name for every month's full moon, from January's wolf moon to December's cold moon. Even if you're just a casual astronomy fan, you've likely heard the name of September's full moon. The harvest moon is the full moon that falls closest to the fall equinox, and it's associated with festivals celebrating the arrival of autumn. Here's what you need to know before catching the event this year.

What is a harvest moon?

You may have heard that the harvest moon is special because it appears larger and darker in the night sky. This may be true depending on what time of night you look at it, but these features are not unique to the harvest moon.

Throughout the year, the moon rises on average 50 minutes later each night than it did the night before. This window shrinks in the days surrounding the fall equinox. In mid-latitudes, the moon will rise over the horizon only 25 minutes to 30 minutes later night after night. This means the moonrise will occur around sunset several evenings in a row.

So what does this mean for the harvest moon? If you're already watching the sunset and you catch the moonrise at the same time, it will appear bigger than usual thanks to something called the moon illusion. It may also take on an orange-y hue because you're gazing at it through the thick filter of the Earth's atmosphere, which absorbs blue light and projects red light. So if you've only seen the full harvest moon around sunset, you may think it always looks especially big and orange, while in reality, any full moon will look that way when it's just above the horizon.

When to See the Harvest Moon

This year, the harvest moon will be visible the night of Saturday, September 14—about a week before the fall equinox on September 23. The moon will reach its fullest state at 12:33 a.m. ET—but if you're still convinced it's not a true harvest moon without that pumpkin-orange color, you can look for it at moonrise at 7:33 p.m. on September 13.