Astronomical! More Than 5,000 Exoplanets Discovered, And Counting

Planetary sleuths are celebrating a milestone this week: the discovery of more than 5,000 planets outside of our solar system — also known as exoplanets.

Studying exoplanets helps us answer existential questions about our place in the universe:

• Are we alone?
• Where do we come from?

"We can look back in time, basically, and look at younger and younger stars and see how planets form," said Jessie Christiansen, lead scientist at NASA's exoplanet archive, which is housed at Caltech in Pasadena.

"We can look at baby stars being born in stellar nurseries and actually start to see evidence of planets forming around them," Christiansen said, "and that can help us work out things like how common planets like the Earth are."

It turns out, according to NASA's archive, they're pretty common.

The discovery of exoplanets has accelerated in the past 30 years, Christiansen said, as techniques and instruments for locating them improve.

To help you wrap your mind around that, JPL put together this audiovisual representation of that increasing pace of discovery:

Scientists have also gotten better at debunking planets that, well, turn out not to be planets.

"When we were trying to hit the 5,000 exoplanets, I made sure we overshot a little bit and landed on 5,005 just because we knew that some planets would come [off the list] in the future," Christiansen said.

Researchers now have a big enough sample size to start looking at exoplanets as a "population," Christiansen said. "We can really start to ask questions about the demographics of the population," she said, "like how common different kinds of planets are and what kinds of stars make different kinds of planets."

Still, there are likely hundreds of billions more exoplanets in the galaxy yet to be discovered.

For now, we'll just leave you with this celebratory recap video from JPL, complete with facts and exoplanet eye candy for the science nerds in all of us: