A new Earth-like planet
This week, scientists using the orbiting Kepler telescope to look in deep space for other Earth-like planets announced that they found the closest matches yet for our Earth. The nearest is still over 500 light years away and the sky is red, but otherwise, it looks ideal and the temperature is just right for liquid water to exist. Graihagh Jackson spoke to the project leader, Willie Torres from the Harvard-Smithsonian Centre for Astrophysics.
Willie - Kepler is a spacecraft launched by NASA in 2009 that was designed to stare at about 100,000 or 150,000 stars for 4 years continuously, looking for changes in brightness that might signal the passage of a planet across the disk of a star.
Graihagh - How do you know that they're planets and not something else transitioning past the star?
Willie - There are many other phenomena that can mimic the signal. One example would an eclipsing binary, a pair of stars that go in front of each other. So, it's up to the scientist to investigate the target in gory detail and determine the likelihood that it is a planet as opposed to some other phenomenon that has nothing to do with a planet.
Graihagh - And that's what you've been doing with your study just released this week.
Willie - That's correct. Of the 12 candidates that we investigated, we were able to confirm 11 of them as being true planets with a very high level of confidence. This essentially doubles the number of planets that are in the habitable zone of their stars and are similar to the Earth in size.
Graihagh - What's so novel about this study because I'm sure scientists have identified, I think something in the region of a thousand exoplanets? So, what's different about your study from all the other previous ones?
Willie - Well, I think the main result is that two of the planets that we have validated are the most similar to the Earth of all the planets known so far. If you consider both their size and the energy they receive from their star jointly. So, if you consider those two conditions that are required for habitability, these two are the most Earth-like planets that we know of so far.
Graihagh - And do these two planets, these particularly promising ones, do they have a name?
Willie - They have numbers. One of them is Kepler 438b and the other one is Kepler 442b.
Graihagh - Do you have pet names for them? They're quite unimaginative.
Willie - Yeah. Unfortunately, that's the way this works. We have so many of these now that you have to give them numbers.
Graihagh - How far away are these planets that we're talking about? Surely, they're hundreds of light years away?
Willie - The range of distances of the 8 planets that we have validated ranges from about 500 light years to about 2500 light years. So, they're pretty far away.
Graihagh - So, my question is then, given that they're so far away, is there any point in really looking at them because we're never going to get there realistically, certainly in the next few hundred years?
Willie - That's a good question and the answer is yes. It is very important to look at these and the reason is that 20 years ago, we didn't know of any planet outside of the solar system. Now, we have approximately 1,000 planets discovered by Kepler and many more discovered from the ground. We are actually talking about now, looking at their atmospheres, looking for biomarkers. Biomarkers are signatures of gases in the atmosphere that could be produced by life. and I anticipate that with the new generation of very large telescopes that will be available 5 to 10 years from now, we will be able to study the atmospheres of many more planets, and actually, be able to look at signs of life as we know it.