Science speeds along so fast that it can be hard sometimes to know exactly what's known. So now and then its helpful to pause and ponder the state of things.

The following 10 statements straddle the line between fact and fiction in space science. If you haven't been paying very close attention, the truthfulness of some might be hard to gauge.

Jot down which side of the fact-fiction line you think each falls, then see the answers below. The challenge, of course, is to score a perfect 10.

1. We have strong evidence that our solar system is not the only one; we know there are many other Suns with planets orbiting them.

2. Some organisms can survive in space for years -- without any kind of protective enclosure.

3. Organisms have been found thriving in scalding water with temperatures as high as 235 degrees Fahrenheit.

4. We now have evidence that some form of life exists beyond Earth, at least in primitive form.

5. We currently have the technology necessary to send astronauts to another star system within a reasonable time span. The only problem is that such a mission would be overwhelmingly expensive.

6. All of the gas giant planets in our solar system (Jupiter, Saturn, Uranus and Neptune) have rings.

7. In the "Star Wars" films, the Imperial TIE Fighters are propelled by ion engines (TIE stands for Twin Ion Engine). While these spacecraft are fictional, real ion engines power some of today's spacecraft.

8. There is no gravity in deep space.

9. The basic premise of teleportation -- made famous in TV's "Star Trek" -- is theoretically sound. In fact, scientists have already "teleported" the quantum state of individual atoms from one location to another.

10. Tatooine, Luke Skywalker's home planet in the "Star Wars" films, has two Suns -- what astronomers would call a binary star system. Scientists have discovered recently that planets really can form within such systems.

1. We have strong evidence that our solar system is not the only one; we know there are many other Suns with planets orbiting them.

SCIENCE FACT

Improved telescopes and detectors have led to the detection of dozens of new planetary systems within the past decade, including several systems containing multiple planets. So far, the limits of technology favor the discovery of large planets, and many are more massive than Jupiter and, surprisingly, hug their stars in scorchingly close orbits that last days instead of years. But some other systems look a lot like our own.

2. Some organisms can survive in space for years -- without any kind of protective enclosure.

SCIENCE FACT

A small colony of the common bacteria Streptococcus mitis stowed away for nearly three years aboard NASA's Surveyor 3, an unmanned spacecraft that landed on the moon in 1967. The crew of Apollo 12 recovered the organisms and brought them back to Earth under sterile conditions. This unplanned experiment proved that certain microorganisms can survive years of radiation exposure, the vacuum of space and deep-freeze, without any nutrient, water or energy source. Some researchers say life could have traveled from Mars to Earth inside a space rock.

3. Organisms have been found thriving in scalding water with temperatures as high as 235 degrees Fahrenheit.

FACT

More than 50 heat-loving microorganisms, or hyperthermophiles, have been found thriving at very high temperatures in such locations as hot springs in Wyoming's Yellowstone National Park and on the walls of deep-sea hydrothermal vents. Some of these species multiply best at 221 degrees Fahrenheit, and can reproduce at up to 235 degrees. Bacteria have also been found thriving under ice near the poles, in a highly alkaline lake, and deep underground, feeding off rock.

4. We now have evidence that some form of life exists beyond Earth, at least in primitive form.

FICTION

While many scientists speculate that extraterrestrial life exists, so far there is no conclusive evidence to prove it. Future missions to Mars, the Jovian moon Europa and future space telescopes will search for definitive answers to this ageless question.

5. We currently have the technology necessary to send astronauts to another star system within a reasonable time span. The only problem is that such a mission would be overwhelmingly expensive.

FICTION

Even the unmanned Voyager spacecraft, which left our solar system years ago at a breathtaking 37,000 miles per hour, would take 76,000 years to reach the nearest star. Because the distances involved are so vast, interstellar travel to another star within a practical time scale would require, among other things, the ability the move a vehicle at or near the speed of light. This is beyond the reach of today's spacecraft -- regardless of funding, according to. Even so, the space agency is looking into the possibilities.

6. All of the gas giant planets in our solar system (Jupiter, Saturn, Uranus and Neptune) have rings.

FACT

Saturn's rings are the most pronounced and visible, but they aren't the only ones. Check out the rings (and clouds) of Uranus and Neptune.

7. In the "Star Wars" films, the Imperial TIE Fighters are propelled by ion engines (TIE stands for Twin Ion Engine). While these spacecraft are fictional, real ion engines power some of today's spacecraft.

FACT

Ion propulsion has long been a staple of science fiction novels, but in recent years it has been successfully tested on a number of unmanned spacecraft, notably NASA's Deep Space 1. Launched in 1998, Deep Space 1 rendezvoused with a distant asteroid and then with a comet, proving that ion propulsion could be used for interplanetary travel. And the European Space Agency just put an ion-powered probe into orbit around the Moon.

8. There is no gravity in deep space.

FICTION

If this were true, the moon would float away from the Earth, and our entire solar system would drift apart. While it's true that gravity gets weaker with distance, it can never be escaped completely, no matter how far you travel in space. Astronauts appear to experience "zero-gravity" because they are in continuous free-fall around the Earth. An interesting twist (or rather, nontwist) to this concept is that the gravity of a black hole works the same way. So, while anything too close to a black hole (including light) will be sucked in and hidden from view, objects at a distance from a black hole feel no greater pull than if the black hole were a star of equal mass. Go figure.

9. The basic premise of teleportation -- made famous in TV's "Star Trek" -- is theoretically sound. In fact, scientists have already "teleported" the quantum state of individual atoms from one location to another.

FACT

As early as the late 1990s, scientists proved they could teleport data using photons, but the photons were absorbed by whatever surface they struck. More recently, physicists at the University of Innsbruck in Austria and at the National Institute of Standards and Technology in Boulder, Colorado, for the first time teleported information between atoms using the principle of quantum entanglement.

Experts say this technology eventually could enable the invention of superfast "quantum computers." But the bad news, at least for sci-fi fans, is that experts don't foresee being able to teleport people in this manner.

10. Tatooine, Luke Skywalker's home planet in the "Star Wars" films, has two Suns -- what astronomers would call a binary star system. Scientists have discovered recently that planets really can form within such systems.

FACT

Double stars, or binary systems, are common in our Milky Way galaxy. Even three-star systems exist in gravitational harmony. Among the more than 100 new planets discovered in recent years, some have been found in binary systems, including 16 Cygni B and 55 Cancri A. So far, alas, no one has found a habitable planet like Luke Skywalker's Tatooine.

• The Greatest Myths, Hoaxes & Mysteries in Astronomy and Space Science

SOURCES: NASA, SPACE.com reporting