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NASA Chat: The Quest for Planets
Artist Concept of Kepler 10bArtist concept of Kepler 10b.
Image credit: NASA
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Artist's concept of Kepler Artist's concept of Kepler in the distant solar system.
Image credit: NASA/JPL-Caltech
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Natalie Batalha typing during the Jan. 10 exoplanet web chat. Natalie Batalha responding to questions during the chat on Jan. 10, 2011.
Image credit: NASA
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NASA's Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system. The discovery of this so-called exoplanet is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010. This new planet discovery was announced Monday Jan. 10 during the 'Exoplanets & Their Host Stars' presentation at the American Astronomical Society (AAS) conference in Seattle, Washington.

Kepler is NASA's first mission to look specifically for Earth-size planets in the habitable zones (areas where liquid water could exist) around stars like our sun. Kepler will spend 3-1/2 years surveying more than 100,000 stars in the Cygnus-Lyra region of our Milky Way galaxy. More than 300 exoplanets have been discovered previously, most of which are low-density gas giants such as Jupiter or Saturn in our own solar system.

Natalie Batalha of the NASA Kepler Mission Team was online answering your questions about this new planet finding on Monday, Jan. 10 from 3:30 p.m. to 4:30 p.m. EST / 12:30 p.m. to 1:30 p.m. PST. Natalie chatted with you live from the conference in Seattle.

About Dr. Natalie Batalha

Natalie Batalha is a professor of physics and astronomy at San Jose State University in the heart of Silicon Valley, California and deputy science team lead for NASA’s Kepler Mission. She holds a bachelor's in physics from the University of California (UC), Berkeley and a doctorate in astrophysics from UC Santa Cruz. Batalha started her career as a stellar spectroscopist studying young, sun-like stars. After a post-doctoral fellowship in Rio de Janeiro, Brazil, Batalha returned to California. Inspired by the growing number of exoplanet discoveries she joined the team led by William Borucki at NASA's Ames Research Center, Moffett Field, Calif., working on transit photometry -- an emerging technology for finding exoplanets. As a member of the Kepler team, Batalha is responsible for the selection of the more than 150,000 stars the spacecraft monitors and works closely with team members at Ames to identify viable planet candidates from Kepler photometry.

Transcript of the Chat

Jason(P): We're working on answering the first few questions. To ask your own, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Oko(Q): How many planets similar to Earth have you discovered?

Natalie(A): Hi guys! This is Natalie, and I'm happy you could join us! Let me start with this question about other discoveries of planets similar to earth. First, we have to establish what we mean by "similar to earth". If we mean earth-size in the habitable zone, then I can say that Kepler has not yet confirmed any such planets and does not expect to be able to until we see at least three transit events. For a planet similar to earth, that will take over three years.

Jason(P): Wow. Lots of questions so far. We're working to answer them right now. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Mr_Wojciaszek(Q): Hello Everyone ! Greetings from Poland ! I want to ask you about this new discovery - what's so special about Kepler 10b and do you think that there may be signs of life there ? By the way what's your opinion about extraterrestrial life in general.

Natalie(A): This discovery of Kepler-10b is special because of the accuracy of the planet properties. Our uncertainties in the mass and radius of the planet are small enough that we can say this is unquestionably a rocky world. We have achieved this accuracy because of the asteroseismic analysis.

Akarsh_Valsan(Q): What really suggested the name ' Kepler' for the magnificent mission?

Natalie(A): The Kepler mission is named after Johannes Kepler -- the famous mathematician who devised the empirical laws of planetary motion in the 1600's. We use his laws to determine the mean distance between the planet and the star. This distance determines whether or not the planet is in the Habitable Zone -- the goldilocks zone where liquid water might be able to pool on the surface of a planet.

HouliHoulihan(Q): Is there an atmosphere on Kepler-10b?

Natalie(A): Of course we do not yet have the exact answer to that question. However, we expect that a planet subjected to such intense radiation from the star it orbits would not be able to hold onto an atmosphere for long.

mtalar(Q): Is the extrasolar planet search the only goal of Kepler?

Natalie(A): This is the prime objective, yes -- to determine if earth-size planets are abundant in our galaxy, paying special attention to those that are potentially habitable. However, we have a group of scientists that comprise the Kepler Asteroseismic Science Consortium (over 300 scientists!). They utilize the exquisite precision of the Kepler data to study the properties of the stars themselves. We fully expect Kepler to revolutionize stellar astrophysics as a result.

Kari(Q): The new planet seems to be very close to the star. Is this typical for exoplanets?

Natalie(A): The short-period planets are easier to see, not necessarily more abundant in the galaxy. The probability that the planet will transit is larger for shorter periods. Also, the shorter the period, the more transits we observse. The more transits we have, the more we can average our measurements together to pu ll out weak signals.

rober(Q): Hi, this is Roberto, from Spain, thank you so much for the possibility to talk to you directly. Why did you chose Cygnus? What does Cygnus have that other zones don´t have?

Natalie(A): We chose CYgnus 1) because it is in the northern hemisphere (and we want to be able to see the region of the sky Kepler targets with our ground-based telescopes largely in the northern hemisphere), 2) the field is far enough away from the Sun at any time of the year, and 3) it is close to the plane of the Mikly Way galaxy where the density of stars is high.

Daren(Q): Hi, is this planet within the "habitable zone" of the star?

Natalie(A): Kepler-10b is definitely NOT in the habitable zone as we define it. The dayside temperature of the planet is expected to be higher than 2500 F!! That's hot enough to melt iron!

WuNgUn(Q): Congrats on this remarkable discovery! Size and composition, this is very similar to our we know yet about it's orbital distance from it's host star?

Natalie(A): Kepler-10b is about 23 times close to its star than Mercury is to our own Sun.

tlland(Q): Can Kepler determine anything about the chemical content of a candidate planet's atmosphere to determine if it would be suitable for life as we know it?

Natalie(A): Kepler can not probe the atmosphere of the planet, no. However, I fully expect other telescopes and missions to do transmission spectroscopy to see if it has an atmosphere. With transmission spectroscopy, you observe the planet when it is right in front of the star (allowing starlight to stream through its atmosphere) and then you observe it when it is not in front of the star. Then, you compare the two to see what the atmosphere might have done to the starlight.

Jason(P): We're working to answer your great questions. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

arralen(Q): What's the Keppler id for the object - can i download the lightcurve anywhere?

Natalie(A): The ID of the star is: KIC 11904151. Have fun!

Thomas(Q): With respect to the planet being the first terrestrial planet from Kepler, how does Kepler-9d fit into this? Was it discovered later?

Natalie(A): Unfortunately, we do not have a Doppler detection of Kepler-9d that would give us its mass. We only have its size. Therefore, we cannot compute the mean density that is so important for understanding its composition.

rober(Q): How do you measure the planet mass, size and the distance to the star? And the planet composition?

Natalie(A): Mass comes from the Doppler measurements of the wobble of the star as the planet/star orit about their commone center of mass. Radius comes from the amount of dimming of starlight that occurs during transit. The distance can be derived if you know the surface temperature and radius of the star. Together they give the intrinsic brightness. We know how bright the star appears to us. Knowing how right it SHOULD be instrinsically allows us to determine how far away it is -- 560 light-years for Kepler-10.

Koreczek(Q): What do you think about life in other planets ? Is that possible ?

Natalie(A): It must be "possible" simp;ly because we exist! Do I think there are other examples of life in our galaxy? in our Universe? Boy, I sure hope so!

Cygnus(Q): What are the prospects for additional planets in the Kepler 10 star system? Any hints?

Natalie(A): There is actually already a very compelling signature of another potential planet in this system. There is a transit event that recurs once every 45 days and is suggestive of a planet a bit larger than 2 times the radius of the Earth.

priyanka(Q): hi natalie. thanks for joining the chat room. i am from india and i wanted to know the various methods used to locate exoplanets. is microlensing one of the methods? if yes...what is it and how is it done? please tell me more about kepler 10b.

Natalie(A): Yes! Microlensing is another technique scientists use to search for planets. From general relativity, we know that mass can bend the path of light as it propagates through the Universe. Imagine you have a distance star with a planet that happens to line up for a short time with a star in the foreground. The light from the distant star/planet will be bent by the mass of the foreground star, causing a sudden brightening of the light that reaches our telescope. This is the basic idea behind microlensing.

HOUPoland(Q): Hi! I am Lech Mankiewicz from Hands-On Universe, Poland. We actively support thehe recent PlanetHunters program ( on the Zooniverse. I wonder what kind of impact Planet Hunters have on the results of the Kepler team. Thank you.

Natalie(A): We are SOOO excited about, and we are hoping to work together as much as possible, sharing information and helping the public as much as we can in their pursuit of planets. I know that there must be planets lurking in that data that we haven't seen, and we really look forward to having an extra million or so pairs of eyes on those light curves.

rober(Q): Where is Kepler telescope located? What kind of light does it use: infrared, visible light?

Natalie(A): The Kepler spacecraft is in an earth-trailing orbit around the Sun. It measures transits in the optical (visible).

Bartek(Q): greetings from Poland, I congratulate the discovery! Will the publication be available on astro-ph?

Natalie(A): Yes! I tried to do that last night, but it didn't compile correctly. We'll probably put the paper on our website ( in the interim.

Jason(P): We're working to answer your great questions. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Denver.C(Q): What makes this discovery stand out

Natalie(A): Certainly it stands ou t becuase it is the first unquestionably rocky world orbiting a star outside our solar system. But more specifically... I think its the fact that all of our best capabilities (photometry, Doppler measurements, and asteroseismology) have converged on this one result.

Lee(Q): Has Kepler made any observations on the nearby Alpha Centauri system, or are there difficulties of viewing any orbiting planets due to how bright the binary system is?

Natalie(A): No, our telescope is pointed at a regiono of sky between Cygnus and Lyra and will point at this same region for the entire duration of the mission.

sylwia_p(Q): how many people take part in Kepler project?

Natalie(A): There are many, many experts involved with Kepler -- from intrument engineers, software engineers, to scientists. THe science team is currently around 50 or 60 individuals. The Kepler-10b paper has more than 50 authors!

Karol(Q): Hi ! what is your greatest discovery

Natalie(A): No question... it's Kepler-10b. So far, that is. :)

Jason(P): To learn more about the Kepler mission, visit or Information about today's announcement can be found at

merrickf(Q): How many candidate Earth like planets do you estimate you will find in the Milky Way galaxy?

Natalie(A): This is an interesting question, but we have ot be more specific about what we mean by "earth-like". If every star we are observing has an earth-size planet in the Habitable Zone, we expect to find on the order of 50 such systems.

DEChengst(Q): What's the plan after the primary mission is over? Would you like to switch to another starfield to catch more Earth like planets, or would like to keep looking at the same starfield to catch longer period planets ?

Natalie(A): Really good question! That's something we are thinking about carefully right now as we plan for the future. So far, our simulations have shown that it would be more advantageous to keep observing the same field to detect the longer period and smaller planets.

mtalar(Q): How is it possible to determin if the planet is in the habitable zone?

Natalie(A): We are using a very simple definition of the Habitable Zone. You put a planet at a certain distance from a star of known properties (Luminosity) and assume that the planet has some reasonable albedo (e.g. how much energy does it absorb versus how much energy does it reflect) and then you calculate the temperature the object would have. If it's below the boiling point of water and higher than about 50 degrees or so (C) above the freezing point, we say that it is in the Habitable Zone.

AREweALONE(Q): Has the NASA Kepler Mission Team confirmed Gliese 581g as an actual planet? People are doubting that it actually exists.

Natalie(A): Gliese 581 is not in the field of stars that Kepler is observing. Yes, this is a very difficult system to understand given the number of very tiny Doppler signatures that one must disentangle.

michał(Q): Is your equipment on the planets of another system can detect signs of life?

Natalie(A): Kepler is NOT able to detect signatures of life (like the presence of Oxygen in an atmosphere, for example). No, this is not our objective. First, we must figure out if earth-size planets outside our Solar System are common.

kianjin(Q): Are there any other planets in this system and have you decided to call this planet 'Vulcan'?

Natalie(A): The team has not necessarily adopted the name VUlcan for this planet. However, it was the first thing that came to my mind when I saw the planet "come alive" in the artists depiction. The Vulcan Telescope -- our precursor to Kepler up at Lick Observatory -- was such a major part of our history, that it really came full circle for me.

magda.tom(Q): Good afternoon. Asteroseismic analysis - could you say a few words about this method and technology? What information does it provide?

Natalie(A): Good question! Just as we use earthquakes to probe the interior of the Earth, we can use star quakes to probe the interior of stars. But how do you see a starquake? Well, Kepler can "see" manifestations of star quakes in the brightness measurements. They produce very high frequency brightness variations at characteristic frequencies. The exact frequencies depend on the size and density of the star in the same way that the sound emitted from a violin differs from the sound emitted by a cello.

Jason(P): We've got time for just a few more questions. To ask a question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Akarsh_Valsan(Q): In which constellation does Kepler-10b really come in?

Natalie(A): The Kepler field of view is between Cygnus and Lyra. Surprisingly, however, there is a tiny corner of Draco that cuts into the field. Kepler-10b happens to be in the constellation Draco.

sylwia_p(Q): Did you find some organism on Kepler-10b?

Natalie(A): Nope! No organisms, nor could we if we wanted to. It wouldn't be a very nice place for organisms like those on earth to live. Carbon-based chemistry wouldn't thrive there. Molecules comprising RNA and DNA couldn't stay intact in such extreme temperatures. Last June you gave us 320 possible target stars with exoplanets. How come only 1 has been announced? Does this mean there are few close to their star - ie that we are finding many in the habitable zone - but you need longer to verify?

Natalie(A): Since June, we have announced Kepler-9b,c,d and Kepler-10b. In addition, a European team has recently announced the confirmation of one of the planets in the June catalog. We will certainly announce each and every planet that we successfully confirm at the very first moment possible.

William(Q): If this planet had been orbiting it's star at a distance similar to how our Earth orbits our sun would Kepler have the sensitivity to detect it?

Natalie(A): Kepler has been designed to be able to detect an earth-size planet (even smaller than Kepler-10b) out at a distance on 1 AU (the orbit of the Earth around the Sun) in three to four years time. So the answer is yes, eventually.

Natalie(P): It's clear to me that we need to do this more often! So many questions that I didn't even get to! Thank you all so much for participating. This is YOUR mission. This is YOUR science. We want you here with us, enjoying these results as much as we are. Thanks again!

Jason(P): Thanks Natalie for the great answers to everyone's questions. We appreciate your taking time out of your day to sit down with us. Our chat is over! Thanks for participating. A transcript will be available within a few business days.