Newswise — Planet-hunting telescopes have recently taken a huge leap in their ability to find “exoplanets,” or planets orbiting other stars. In just the past six months, astronomers have announced the discovery of more than 700 such worlds, bringing the total to more than 1,700. These discoveries include the first Earth-size planet found in what’s called the habitable zone of a star, where liquid water could exist; the oldest known planet that could support life; and an unusual giant planet that orbits its star at 2,000 times the distance between Earth and our sun.

Earlier this week, three planet hunters came together during a live Google Hangout to discuss the discovery boom, consider what state-of-the-art telescopes can – and can’t – tell us about exoplanets, as well as ponder the likelihood of finding evidence of life on another planet.

“We’re in this era now where there are 1,700 planets known, and [for many of those planets] there’s really no analogy in our solar system,” said Bruce Macintosh, a member of the Kavli Institute for Particle Astrophysics and Cosmology and the principal investigator for the Gemini Planet Imager. “With the exception of a few specialized individuals, we have no idea what the heck they’re made of. And so this enormous puzzle about how the universe has made systems so different from our own is extraordinarily exciting.”

Even though even the closest exoplanets are distant objects, astrophysicists are able to measure many of their characteristics including size, mass and density. They can now also determine some of the chemical make-up of a planet’s atmosphere – and are able to detect more detail by the year.

That will help not only reveal the conditions on individual planets, but also answer big-picture questions like how planetary systems form and just how common the types of planets in our own solar system are. It should also move us closer to answering the biggest of the big questions: whether life exists elsewhere. Said Marie-Eve Naud, a University of Montreal PhD student who recently helped discover a new giant planet, “I’m not that confident, but I dream that we will have a hint of the answer by the time I leave this planet.”

Zachory Berta-Thompson, the Torres Fellow for Exoplanetary Research at the MIT Kavli Institute for Astrophysics and Space Research, shares Naud’s cautious optimism that in the coming years there will be significant new insight toward answering this question. “In the next decade, we are just barely at the edge of being able to detect molecular oxygen in a planet’s atmosphere,” he said. “If we find the right planet—meaning it’s the right size and the right temperature, and around one of the closest very small stars, so it’s very easy to observe—then… you just might be able to do it.” While not proof of life, the observation of molecular oxygen would be a big step in that direction.

“What is really fascinating at this stage of exoplanet science is that we have many methods, and all the methods can… bring different information,” said Naud. “When we are able to combine different methods, we are able to see so much more.”

The complete discussion recorded live is available at