The Kepler Effect: A Cascade of Planetary Discoveries

On February 26th, 2014, the Kepler science team shared some exciting news - they found 715 new planets outside of our solar system! This discovery nearly doubled the total number of confirmed alien planets. But how did they find so many at once? Since the Kepler Telescope was launched in 2009, we've been finding new planets slowly. So where did these 715 new planets come from and are they really out there, or are they just educated guesses?

So, here's the thing - a big part of this whole discovery thing is not just what we've seen, but also how likely it is that what we're seeing are actually planets. Let me break it down for you. The Kepler space telescope has this cool tool called a photometer. It's all about measuring how bright light is using a huge lens that's almost a meter wide. This camera is actually the biggest one we've ever sent into space. And guess what? It finds planets by basically looking out for their shadows. Pretty neat, right?

Planets outside our solar system are hard to see because they are small and far away, but we can see stars easily. Sometimes when a planet passes in front of a star, it blocks some of the star's light. The Kepler photometer can detect this dimming of light and record it. However, the dimming could also be caused by other things like solar events or space debris floating by. Kepler continues to watch the same star to see if it dims again. If the dimming happens again later for the same amount of time and by the same amount, then we can be pretty sure there's something orbiting that star.

Kepler watches over a hundred thousand stars for fluctuations like these. When it spots one, it marks it as a potential planet. The Kepler science team then works to confirm which of these potential planets are actually real planets, as there are other reasons stars can seem to dim.

Picture this: there are two stars orbiting each other behind the star we're studying. These pairs are known as binary stars and they can cause false positives in Kepler's observations.

Here's a simple way to think about it: When two stars line up with the star we're observing, one of them will block the other as they orbit each other. This can make the whole area, including the star we're interested in, appear less bright.

Unfortunately, binary stars are very common. In fact, if Kepler detects a star with only one possible planet around it, there's only a 25% chance that it's actually a planet.

Sometimes a star may have more than one candidate running for the office of an exoplanet. This is where probability comes into play. Planets tend to cluster around the same star, similar to how we have eight planets in our own solar system. However, whether a star has a pair of binary stars is random. False positives are evenly distributed among all of the planetary candidates that Kepler finds. Statistically speaking, observing one planet around a star makes you thirty times more likely to see another planet. So, it's all about probability and chance!

When you see two planets, there's a good chance you'll see a third one. The odds of a single planet candidate being a real planet are low, but if there are three candidates around one star, they are most likely planets. We can be 99% sure that they are planets without needing more readings. This logic is how the Kepler science team announced finding 715 new planets at once.

Astronomers use a method called "verification by multiplicity" to confirm if a planetary candidate is an actual planet. By calculating Bayesian probabilities, they can determine the likelihood of a candidate being a planet. If a candidate is 100 times more likely to be a planet than something else, it is considered officially discovered. The Kepler science team identified 715 new planets as candidates, but they were confirmed as planets through mathematical analysis.