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An illustration of the variety of planets in our galaxy being detected by NASA’s Kepler spacecraft. Research on their frequency suggests one in six stars in the Milky Way is orbited by an Earth-size planet, which means there would be at least 17 billion planets on which life might exist. Photo by C. Pulliam & D. Aguilar, courtesy of the Harvard-Smithsonian Center for Astrophysics.

Though we may not find life on Mars, a new study shows that we still have at least 17 billion other chances. Astrophysicist Francois Fressin recently led a team of researchers at the Harvard-Smithsonian Center for Astrophysics in analyzing three years of data from Kepler, a space observatory launched in 2009 to discover Earth-like planets, and found that one in six stars in our galaxy is orbited by a planet roughly the same size as our own.

Kepler collects data by monitoring instances of periodic dimming in the light emitted from more than 160,000 stars. These tiny eclipses, if regular, suggest the presence of planets in orbit as they cross the stars’ centers. The technique is not foolproof, though. Of close to 2,700 planetary candidates identified in Kepler’s three years of observation, scientists were unsure of how many were bona fide Earth-size planets and how many were false positives—two stars themselves crossing, for instance, or other factors that produce similar dimming effects.

Fressin’s job was to find a way of vetting Kepler’s results to determine the observatory’s accuracy. “It requires some work,” he says. “What we are doing is a simulation of all the astrophysical configurations we could think of that could mimic a planet.”

By imagining all possibilities of what could not be Earth-sized planets, that is, Fressin and his team devised a formula to predict what percentage of potential planetary candidates actually are planets. His simulation showed that imposters only could account for 9.5 percent of the candidates, which suggests that the remaining 90.5 percent are real.

Fressin’s results, which show that at the orbital distances studied, one in six stars in the Milky Way is orbited by an Earth-sized planet. About a fourth of all stars have a super-Earth in orbit, and the same fraction have a mini-Neptune. Only about 3 percent of stars have a large Neptune, and only 5 percent a gas giant. Photo by F. Fressin, courtesy of the Harvard-Smithsonian Center for Astrophysics.

Based on the roughly 100 billion stars in the Milky Way, Fressin was able to estimate that about 17 percent of the stars in our galaxy—a whopping 17 billion—have an Earth-size planet orbiting within the same distance as Mercury to the sun. He reported his team’s findings on Tuesday, just a day before another group of astronomers from the University of California, Berkeley, and the University of Hawaii at Manoa announced nearly identical findings.

This result is a big deal, Fressin says, because it allows scientists to assert for the first time with any certainty that Kepler is reliably recording the occurrence of small planets, and it demonstrates that we are far, far from being alone in our planetary size in the galaxy—an affirmation that gives us a glimpse at just how many possibilities there are for extraterrestrial life.

“It’s very difficult to know what to look for when we look for another life,” Fressin says, because we know of only one example—our planet. He explains that larger gaseous planets appear too volatile and smaller planets seem not to have enough atmosphere to support living creatures, so scouring our galaxy for like-sized planets probably is our best bet if we ever hope to find aliens.

This question of whether or not life exists elsewhere in the universe is what drives Fressin’s research. Though he admits that both possibilities are “scary,” he views the process towards discovery as essential to our self-understanding. In life, “you can’t really know yourself without contact with others,” he says. “You can’t really know the country in which you dwell if you haven’t visited other countries. I’m under the impression that it could be the same for what living as inhabitants of the Earth means. You need to know about the other worlds.”

Fressin mentions that he is “optimistic” that researchers will find signs of extra-terrestrial life in the “maybe-not-so-distant-future,” but cautions that finding life similar to ours is a much greater challenge: “It’s the question of whether we will find evidence of intelligent, advanced civilizations that is tougher to answer.

“But the small steps are worth taking,” he says.

We love candy, to eat and to look at. Big Suckers, from the portfolio Seven Still Lifes and a Silver Landscape. Wayne Thiebaud, 1971. Courtesy of the American Art Museum.

Here at the Smithsonian, we’ve got quite a sweet tooth. From Wayne Thiebaud’s fixation on all things sugar to astronaut candy, the collection is full of treats. So this Halloween, look back on the trick or treats that might have been and ahead to the sure-to-be glorious tradition of outer space candy collecting.

NECCO Wafers, Hershey’s Kisses and Heath bars had been delighting mouths for years by the roaring twenties. But the decade proved to be a decadent one, with the introduction of the Milky Way candy bar, Milk Duds, Baby Ruth bar and Reese’s Peanut Butter Cups.

Unfortunately, the term “candy” was thrown around a little loosely. Laxatives and prescriptive chews were also permitted to call themselves candy. Candy expert and Rutgers University professor Samira Kawash told Food and Think, “The first candies were medicinal! An apothecary in the 18th century would prescribe you sugar candy for things like chest ailments or digestion problems. Back then, the “spoonful of sugar” idea was literal—if you had some sort of unpleasant medicine to take, usually a concoction of herbs that might not taste very good, the apothecary would suspend it in sugar.”

Good thing trick or treating didn’t take off in America until the mid 20th century, otherwise we’re pretty sure some forgetful homeowner would’ve undoubtedly tried to pass these off as Halloween handouts.

Sterling Products made this “candy cathartic” around 1925. Courtesy of the American History Museum

Round worms were no match for Worm Candy! Courtesy of the American History Museum

Candy laxative fans had multiple options. Courtesy of the American History Museum

By the 1940s and 50s, Americans began their affair with candy in earnest. The tradition of trick-or-treating, originally a much more social activity that entailed visiting in neighbors’ homes, began in the mid-20th century. In 1943, Hershey’s produced its Tropical Bar for troops in WWII as a heat-resistant, high-energy snack. According to the American History Museum the product, called Field Ration D, was ”so successful that by the end of 1945, approximately 24 million bars were being produced every week.”

Tropical chocolate was designed not too melt in your hands. Courtesy of the American History Museum

From the battle front to the final frontier, candy’s next stop was outer space. Maybe not as revolutionary as freeze-dried astronaut ice cream, the space-bound candy treats were still pretty delicious orbiting the Earth.

The debate continues into space: plain or peanut? Courtesy of the Air and Space Museum.

And the relationship with candy continues: In July of this summer, the famous confectioners Mars Inc. donated $5 million to help construct an exhibit titled “American Enterprise” about business and innovation, set to open in 2015.

Artist's conception of the Milky Way using new measurements. Courtesy of Harvard-Smithsonian Center for Astrophysics

The Milky Way galaxy, Earth’s ride through space, is more mini-van than mini-Cooper, report scientists at the American Astronomical Society meeting this week. New technology allowing them to make high-precision measurements showed that not only is the Milky Way moving 100,000 miles per hour faster than previously thought, it is also 50 percent larger.

To make sense of the news, I spoke with Mark Reid, an astronomer at the Harvard-Smithsonian Center for Astrophysics who contributed to this research.

Q: What does the new calculation of a faster spinning galaxy mean for us?

A: Nothing. We wouldn’t notice the difference at all. If we lived billions of years, then we would certainly see that all the constellations and the patterns in the Milky Way would change a little faster but we’re not going to notice that.

Q: How does it impact us then?

The Milky Way galaxy now has the same rotation speed with the Andromeda Galaxy, our neighbor. That means it’s as massive as the Andromeda Galaxy and there’s a lot of ramifications for the evolution of the galaxies around us. For example, the Milky Way and Andromeda are the two biggest galaxies in what we call the Local Group, this little neck of the woods of the universe. There’s a good chance that these two galaxies will hit each other in about five billion years or so. Now, by realizing that there’s more mass in the Milky Way than we thought, [this discovery] makes this more likely and that it will happen a bit sooner because there’s more gravity pulling them together.

Q: What happens when two galaxies collide?

A: If you’re sitting here on the Earth, you would never know it because there’s so much empty space between all the stars. If we have two populations of stars merging through each other, they won’t collide or things like that. But what will happen is the Milky Way and the other galaxy Andromeda will change dramatically. They might merge into one galaxy for example. So over very long time periods the entire sky would change. In fact, it’s possible that the sun and Earth could get ejected out of the galaxy in such a collision. That’s a distinct possibility. It wouldn’t affect life here, but it would certainly affect what we see when we look out into the universe.

For more on this story, see reporting done by The New York Times, Wired, and Discover.