The movies are not exactly known for portraying scientific fact and science fiction in particular is a genre often fraught with factual errors. In spite of this, many people take some of the most common tropes of science fiction as science fact and, on the subject of space, there are perhaps more common misconceptions than there are with just about any other genre.

Just to give you an idea of just how scientifically inaccurate many movies are, NASA used the 1998 asteroid disaster movie, Armageddon, as part of its training program to point out examples of almost 200 different scientific errors.

Here are five of the most common myths about space which you may already believe.

1.  Unprotected Astronauts Explode in Space

astronaut explodingFor the sake of dramatic effect, the vast majority of science fiction movies, particularly older ones, portray exposure to space in an incredibly unrealistic way. In the 1981 movie, Outland, a man explodes when exposed to space, in the 1990 film, Total Recall, eyes and tongues pop out of people’s heads when exposed to the near vacuum of the surface of Mars.

The reality is completely different.

The only movie to actually get it right was Stanley Kubrick’s 2001: A Space Odyssey in 1968. Exposure to space is certainly deadly, however, although you could survive it for up to a minute without any permanent damage, provided you exhale. What will kill you is asphyxiation and deoxygenation of the blood long before evaporating body liquids or radiation.

2.  Asteroid Belts are Dangerous to Spacecraft

asteroid beltThe movies often portray the perils of spacecraft flying through asteroid belts, such as the one in our own solar system between the orbits of Mars and Jupiter. Spacecraft have to dodge thousands of flying rocks coming at them from every direction.

What these movies seem to forget is that space is actually rather large and, in spite of there being hundreds of thousands of asteroids in the Asteroid Belt, they also cover an unspeakably enormous distance. The actual density of asteroids in this region of our solar system is about one per 400,000 square miles. Every space probe that has ever passed through the Asteroid Belt has done so unharmed and the odds of hitting something are about one in a billion.

3.  Our Solar System Is Unique

solar systemScience fiction space operas almost invariably feature other worlds beyond our own solar system and this is one of the few facts that they do get right. In spite of this, if you ask the average person how many planets there are, they will answer with ‘eight’ or even ‘nine’ if they’re not aware of Pluto’s demotion to a dwarf planet.

In fact, however, the number of other planets which have been discovered, as of April, 2013, is closer to 900 with thousands more yet to be confirmed. Our solar system is nothing unique. Countless millions of other stars, much like our own, have extensive planetary systems. The expected number of planets in our galaxy and the rest of the universe is probably around one followed by 24 zeros.

4.  There Is Sound in Space

Movies set in space are often very noisy, again for the sake of dramatic effect. The only well-known exception is, again, 2001: A Space Odyssey. Somehow, Stanley Kubrick managed to get almost everything right with regards to scientific accuracy in that movie.

There is, in fact, no sound in the vacuum of space due to the fact that there is no atmosphere for the sound waves to vibrate in. Astronauts instead need to use radio systems built into their space suits in order to keep in contact. Where there is air, there is sound, although sound on the surface of other planets, such as Mars, is different to sound on Earth. Due to its extremely tenuous atmosphere, sounds on the surface of Mars are expected to be much fainter and slightly higher in pitch.

5.  There Is No Gravity in Space

Gravity is that useful force of nature that stops us toppling into the sky the moment we go down under. Astronauts famously float around in zero gravity whether they’re completing space walks or relaxing during their free time aboard the International Space Station. This is actually known as microgravity and the apparent weightlessness is caused by the space station’s velocity and direction of travel.

As for there being no gravity in space, nothing could be further from the truth. It is the force of gravity alone which keeps objects as distant as Pluto in orbit of the Sun and the Sun itself in orbit of the centre of the Milky Way galaxy.