Eight new planets found in 'Goldilocks' zone

January 6, 2015
This artist's conception depicts an Earth-like planet orbiting an evolved star that has formed a stunning Credit: David A. Aguilar/CfA

Astronomers announced today that they have found eight new planets in the "Goldilocks" zone of their stars, orbiting at a distance where liquid water can exist on the planet's surface. This doubles the number of small planets (less than twice the diameter of Earth) believed to be in the habitable zone of their parent stars. Among these eight, the team identified two that are the most similar to Earth of any known exoplanets to date.

"Most of these planets have a good chance of being rocky, like Earth," says lead author Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics (CfA).

These findings were announced today in a press conference at a meeting of the American Astronomical Society.

The two most Earth-like planets of the group are Kepler-438b and Kepler-442b. Both orbit red dwarf stars that are smaller and cooler than our Sun. Kepler-438b circles its star every 35 days, while Kepler-442b completes one orbit every 112 days.

With a diameter just 12 percent bigger than Earth, Kepler-438b has a 70-percent chance of being rocky, according to the team's calculations. Kepler-442b is about one-third larger than Earth, but still has a 60-percent chance of being rocky.

To be in the , an exoplanet must receive about as much sunlight as Earth. Too much, and any water would boil away as steam. Too little, and water will freeze solid.

"For our calculations we chose to adopt the broadest possible limits that can plausibly lead to suitable conditions for life," says Torres.

Kepler-438b receives about 40 percent more light than Earth. (In comparison, Venus gets twice as much solar radiation as Earth.) As a result, the team calculates it has a 70 percent likelihood of being in the habitable zone of its star.

Kepler-442b get about two-thirds as much light as Earth. The scientists give it a 97 percent chance of being in the habitable zone.

"We don't know for sure whether any of the planets in our sample are truly habitable," explains second author David Kipping of the CfA. "All we can say is that they're promising candidates."

Prior to this, the two most Earth-like planets known were Kepler-186f, which is 1.1 times the size of Earth and receives 32 percent as much light, and Kepler-62f, which is 1.4 times the size of Earth and gets 41 percent as much light.

The team studied planetary candidates first identified by NASA's Kepler mission. All of the planets were too small to confirm by measuring their masses. Instead, the team validated them by using a computer program called BLENDER to determine that they are statistically likely to be planets. BLENDER was developed by Torres and colleague Francois Fressin, and runs on the Pleaides supercomputer at NASA Ames. This is the same method that has been used previously to validate some of Kepler's most iconic finds, including the first two Earth-size planets around a Sun-like star and the first exoplanet smaller than Mercury.

After the BLENDER analysis, the team spent another year gathering follow-up observations in the form of high-resolution spectroscopy, adaptive optics imaging, and speckle interferometry to thoroughly characterize the systems.

Those follow-up observations also revealed that four of the newly validated planets are in multiple-star systems. However, the companion stars are distant and don't significantly influence the planets.

As with many Kepler discoveries, the newly found are distant enough to make additional observations challenging. Kepler-438b is located 470 light-years from Earth while the more distant Kepler-442b is 1,100 light-years away.

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22 comments

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Vignesh R P
1.4 / 5 (7) Jan 06, 2015
I really have a doubt for a long time. According to their observations, Kepler-438b is located 470 light-years and Kepler-442b is 1,100 light-years away from the earth. If we are observing the planet now, that means we are observing the planet which is 1,100 years ago, i.e., we are looking at the past. Then what would be the probability of life that exist in those planets? Or what is the major advantage of exploring those habitable planets? The life may be completely destroyed, if it was so.
Surly
5 / 5 (9) Jan 06, 2015
@Vignesh: Life on Earth has existed for ~3.8 billion years. If there is life on one of those planets, it is unlikely that it would go extinct in the relatively short period that light took to get here from there.

We can't make a very good estimate of how likely it is that life exists on those planets, because we don't know much about those planets except their size and location. To have more information, we'd need to use spectroscopy to see what their atmosphere is made of. That would give us evidence as to whether photosynthesis is happening there.

Kepler is too small to do spectroscopy on a planet's atmosphere. But the James Webb telescope (which should launch in 2018) should be able to.
Zenmaster
5 / 5 (2) Jan 06, 2015
@Surly: "Kepler is too small to do spectroscopy on a planet's atmosphere. But the James Webb telescope (which should launch in 2018) should be able to."

Isn't James Webb designed to detect wavelengths much longer than required to determine composition of planet atmospheres? Elements are in the visible range ~300-900nm correct?
Uncle Ira
4.6 / 5 (9) Jan 06, 2015
Or what is the major advantage of exploring those habitable planets? The life may be completely destroyed, if it was so.


@ Vignish-Skippy. How you are? I'm fine and dandy thanks.

Well I'm not the real scientist-Skippy so what I say about why probably doesn't count for much. But for ol Ira-Skippy (that's me) the major big advantage of exploring them is just to learn more about them. Because I know if it is interesting to me it's got to be really big interesting to the real scientist-Skippys. Maybe learning something about them will tell something more about us.
AlienOverlord
1 / 5 (7) Jan 06, 2015
What's the point? Say a lightyear equals one mile...Then the earth is one inch from the Sun and Pluto is six feet from the Sun. The closest star is four miles. The only possible way for us to get there without warp drive is if the area between solar systems run at a different time speed. So, my question is; when a star warps space, does it speed time up or slow it down?
michael_draut
2.8 / 5 (6) Jan 07, 2015
Other than just shear science satisfaction, practically speaking this all has little application for us earthlings. Why not ramp up and put as much energy into creating habitat on planets in our own solar system? Like Venus, Mars or our own Moon? Seems to be a waste of money.
ScottyB
4.4 / 5 (7) Jan 07, 2015
Seems to be a waste of money.

Finding out weather we are alone in the universe is a waste of money??? Okay then
CreepyD
5 / 5 (2) Jan 07, 2015
@AlienOverlord..
I believe Einstein's theory shows that as you approach the speed of light, time for those going that fast slows down.
To the point that if you were moving at 0.99c you would be able to travel to the edge of the visible universe within your lifetime.
Of course, getting to that speed is another matter entirely.
Torbjorn_Larsson_OM
5 / 5 (8) Jan 07, 2015
@Surly: "Kepler is too small to do spectroscopy on a planet's atmosphere. But the James Webb telescope (which should launch in 2018) should be able to."

As I remember it, unfortunately only on gas giants and quite close at that.

The plan is that, starting with TESS 2017-2019, find out close habitable terrestrial planets, then start to characterize atmospheres, starting with the 30 m telescopes that starts in the early 20's, on those around dwarfs (red and white) were the signal-to-noise ratio means it isn't as demanding.

@AlienLord, michael_draut: "What's the point?", "Seems to be a waste of money."

Assuming you aren't just trolling (a common troll plain) and are genuinely intersted in the science, let me point to the NASA papers that reserached if science is well spent money. It is, it has one of the best ROI there is.

The problem is that no one can predict what gives the R on I. But it is mitigated by that it is all reinforcing.
hurricane25
5 / 5 (3) Jan 07, 2015
What's the point? Say a lightyear equals one mile...Then the earth is one inch from the Sun and Pluto is six feet from the Sun. The closest star is four miles. The only possible way for us to get there without warp drive is if the area between solar systems run at a different time speed. So, my question is; when a star warps space, does it speed time up or slow it down?


Knowledge
The Abiity to understand our place
Possible future exploration.

Worth every cent! Science normally is. Oh'yess, you're one of those small government people that hate science and exploration.
michael_draut
1 / 5 (3) Jan 08, 2015

@hurricane25, @Torbjorn_Larsson_OM, @ScottyB
Knowledge
The Abiity to understand our place
Possible future exploration.

Worth every cent! Science normally is. Oh'yess, you're one of those small government people that hate science and exploration.

It is typical in the liberal academia not to acknowledge that there may just be other ventures that would be as useful if not more so, producing better understanding of our own planet and significantly more knowledge for existing generations to apply. Several of you must be Star Wars freaks salivating over your own personal agenda.

Why not look within our own solar system? Venus? Mars? Our own moon for God's sake! Colonizing them, Our oceans... quit chasing Darth Vader and do something that will be useful and practical. And yes, spending untold millions for what? More theory, more money? Shame on you...
Torbjorn_Larsson_OM
5 / 5 (4) Jan 08, 2015
@michael_draut: "Oh'yess, you're one of those small government people that hate science and exploration."

Did you even read my comment?

BTW, you comment is half loutish ("small"), half conspiracy theory ("government").

Besides that, you didn't respond to the reference (except by unsubstantiated handwaving).

I think we are done here, there is no ground for a further discussion on the usefulness of science and especially astrobiology. Meanwhile, astrobiology is enormously successful (exponential increase in found planets, ...) and enormously marketable. (See e.g. the new antibiotic that is just found, that will means billion less in costs and billions over the years in gained income. That is the use of science, and as per the ref astrobiology.)
Benni
1.7 / 5 (11) Jan 09, 2015
We've known for a long time there are other planets orbiting other stars, but please, save it (the repetitive announcements).......wake me up when they've discovered life on one of'em.
Benni
1.5 / 5 (8) Jan 09, 2015
We've known for a long time there are other planets orbiting other stars, but please, save it (the repetitive announcements).......wake me up when they've discovered life on one of'em.


Maggie, ira: I don't mean you ROCs, I'm referring to real life.
Mike_Massen
3.7 / 5 (3) Jan 14, 2015
Ren82 muttered
Search for planets suitable for life in our galaxy is just well paid business that needs advertising
Wrong. As any astronomer reports not much money & not compared to the billions under control of the Vatican !

Ren82 needs education
At such cosmic distances we can not be sure for the accuracy of the measurements due to large errors and noises from the equipment itself
Not heard of spectroscopy then & pray tell what r the error bars ?

Ren82 claimed
In this vast universe certainly has planets at the appropriate distance from its star to allow liquid water.. Life does not arise by random events
Evidence shows the opposite, complexity does routinely arise from simplicity, ONE example genetic algorithms, ONE other is DNA base pairs from simple chemistry - all it takes is permutations & time, both of which we have in IMMENSE abundance,

Ren82, U have been told this before - what is a better tested hypothesis ?

Ren82 like religion is ONLY about claim !
Mike_Massen
3.7 / 5 (3) Jan 14, 2015
Ren82 claimed
There is no mechanism in nature through which matter can be self organize in complex functional physical systems by itself
Wrong. Protons & electrons self-organise into atoms & molecules, those also then go on to self-organise into larger molecules.

eg. DNA base pairs, ONE example is formamide leads to Guanine

Ren82 you have been told this before & I have asked what is a better testable hypothesis ?

Ren82 you make claims of a heavenly father, evidence from the bible proves he is nasty !

Is that the best a book can do ONLY make claims, very common, without substance !

Ren82 almost got there
In reality act reverse process of degradation of complex systems over time
Yes, its called aging, thats why we live VERY short periods of time.

Ren82 correct
Therefore, living organisms, man and everything created by him lose its original features and functionality over time, regardless of maintenance
By 'him' you mean god, yes not reliable !
Mike_Massen
3 / 5 (2) Jan 14, 2015
AlienOverlord claimed
The only possible way for us to get there without warp drive is if the area between solar systems run at a different time speed
No. Special Relativity (SR) allows you to get even across the galaxy in approx 25 yrs ship time but, those on earth would have ages approx 50,000+ years - as would those at the destination.

You may end up alone but you would have knowledge.

The so called Warping of space/time would be observable by you in the craft as Lorentz Contraction.

All you need are power & propulsion (given we have the intellect & engineering to maintain viable habitation) - both available via nuclear power, one could accelerate well at 1G or a bit more for long enough.

In fact according to SR you could get to Alpha/Proxima Centauri & back in less than a lifetime of ships time at less than 1G and even get back in less than 50 yrs overall Earth time, depends on a few details, the base physics including SR does NOT exclude it...
Mike_Massen
3 / 5 (2) Jan 14, 2015
michael_draut with negligible imagination
Other than just shear science satisfaction, practically speaking this all has little application for us earthlings
Wrong. The engineering challenges are useful to address, colonies/outposts on Mars, Europa etc offer diversity, pioneering & exploration advances which become useful on Earth.

Would be pretty boring just to look up & NOT craft a plan of exploration, wasnt USA explored initially - doh !

michael_draut doesn't understand economics
Why not ramp up and put as much energy into creating habitat on planets in our own solar system? Like Venus, Mars or our own Moon? Seems to be a waste of money.
Not a waste at all for reasons given. All these types af activities are effectively paid for, an odd concept I know, but the so called money needed, given availability of resources & energy balance only require direction of resources, money in that context is not actually lost as such, it is competitive however...
ScottyB
not rated yet Jan 26, 2015
@Torbjorn_Larsson_OM

Interesting, if man kind only explored what was in their local area then imagine where we would be today.. we certainly wouldn't be able to have this discussion thousands of miles away from each other. Yes Exploring out local sol system is something that should and more crucially IS being done, there are hundreds of experiments in our "Local" sol system, branching out and seeing what's further afield seem to me to be the next logical course of action.
Returners
2.3 / 5 (3) Feb 07, 2015
We would need Warp Drive or the makings of a type 3 interstellar network of boosting stations to communicate over these distances, and it would take scores of generations for a round trip signal. Such communications become more like "time capsules" or "if anybody cares, here's this nugget of science we found" type scenarios.

442b would be approximately 2 Earth masses, assuming same composition as Earth. Thus it would be cold in terms of it's solar input, but it is likely geologically warm unless it's much older than the Earth, due to it's larger size.

Who knows what atmosphere it could have, or how big the atmosphere could be. At that temperature it could maintain a carbon-rich atmosphere, or a nitrogen rich, or almost any gas we can think of, due to higher surface gravity to trap more atmospheric compounds.

I would expect that larger planets have larger atmospheres, so we would expect a dense atmosphere, assuming same composition.
Returners
1 / 5 (2) Feb 07, 2015
Planetary composition isn't necessarily a good indicator of atmospheric composition, because you have to consider other factors, such as the age of the planet.

I wonder how massive a planet needs to be to rob mass from the surface of a star during a red giant phase? If this planet is "old" and survived a red giant phase of a star it may have abnormally high hydrogen and helium content, but could also have neon, oxygen, and other gases.

Theory would be solar-relative snowball Earth, with a thicker than normal atmosphere containing stellar remnants from the host Star's previous phase cycle. Thicker than average atmosphere for a rocky planet and possibly super-oceans due to the potentiality of enormous amounts of oxygen and hydrogen.

I am assuming it picked up heavy gases (called metals in astronomy, but in chemistry and geology they are called gases) during the previous stellar phase.

Returners
1 / 5 (2) Feb 07, 2015
If the planet started out with identical composition as Earth, then it would be expected to be about 17% geologically warmer than Earth, which means that if it was the same age, it's surface would actually be hotter than Earth even though it receives less Sun light.

It may have a molten surface if it's age is similar to Earth. If it is older than Earth it might be cooled down into Earth temperature ranges, but without being able to predict the conditions of hte atmosphere it would never be worth it to fly there in a ship. That would be too big of an investment for any conceivable civilization to risk finding an uninhabitable "cold venus" scenario with 100 atmospheres worth of CO2 on top of a ball of ice....or a geologically hot-solar cool planet with a molten surface; either of those scenarios would be a disaster for exploration or colonization.

We need to be able to rule those types of things out ahead of time.

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