On the first day of the American Astronomical Society meeting in Boston, the NASA Kepler team held a press conference to present an update on the mission.

[See the press event slides, with presenters' voices]

It was the first of 50 Kepler presentations at the conference. The scientists on the panel talked about a range of topics, including how to calculate the frequency of Earth-like planets; "flat" multiple-planetary systems; new methods for validating hundreds of planets found by Kepler; and how to tell the age of a star.

Kepler is a statistical mission that will determine the frequency of planets in or near the habitable zone. The habitable zone is the region around a star where water on a planet’s surface could be liquid. In pursuit of this goal, Kepler has already continuously observed about 156,000 stars for more than 2 years. It’s made more than 5.5 billion brightness measurements. As announced in February 2011, Kepler scientists have identified 1,235 planetary candidates, and hundreds more are anticipated as the mission proceeds. Kepler’s observations are already transforming our understanding of planetary systems.

What is the Kepler Mission about?

	William Borucki, Kepler Principal Investigator.

William Borucki of NASA Ames Research Center is the principal investigator of the Kepler mission, a project that he’s worked upon for more than 25 years. He led off the presentations by explaining that the goal of the Kepler mission is to discover how common Earth-size planets are in the habitable zone. Secondly, how many planetary systems exist in our Milky Way galaxy, and what are they like? He further described that a major secondary benefit of the mission is the delivery of the most precise data on the brightness and variability of stars ever available to astronomers. This data provides insight into the lives of stars, the dynamics of stellar systems, and the physics of the many variable stars that populate Kepler's field of view.

	Kepler mission launch count down (up) clock shows 808 days elapsed from Kepler launch as of 2011 May 23, the day of this press conference.

Links to previous related news items:

• February 2011 Kepler Data Release (1,235 candidates including the first Earth-size planet candidates, the first candidates in the habitable zone, and 5 both near Earth-size and in the habitable zone of their stars.
• Kepler-11 Planetary System with the most confirmed transiting planets ever discovered (six planets)
• YouTube video of 2011 Feb 1 news conference on the Data Release and Kepler-11, along with the follow-up question session
• Kepler's first near Earth size rocky planet (Kepler-10b; 2011 Jan 10)
• Kepler Discoveries page

	1,235 Planet Candidates and Their Stars Jason Rowe's graphic of 1,235 planet candidates and their parent stars. See also animation of Kepler candidate multiple planet systems.

Is Kepler finding as many multi-planet systems as expected?

	David Latham, Kepler Co-Investigator.

David Latham, Harvard Smithsonian Center for Astrophysics, next toured Kepler’s “astounding haul” of multiple planet systems. “We didn’t anticipate that we would find so many multiple-planet systems. We thought we might see two or three. Instead, we found more than 100," he said. Of the 1,235 planet candidates announced in February, 827 are single star-planet systems, while 408 planet candidates are found in 170 multiple-planet systems, each with 2 to 6 planets. They are in amazingly flat systems, with all their planets lined up in the same orbital plane within 1 degree. This is in contrast to our solar system, whose planets have orbits that are more tilted. These systems are described in Latham, et. al, “A First Comparison of Kepler Planet Candidates in Single and Multiple Systems.
[http://arxiv.org/abs/1103.3896]
See also separate press release.

Kepler is good at finding smaller planets, unlike the majority of planetary discoveries made by ground-based telescopes using the “Doppler method,” which cannot detect small planets. Thus, small planets are hard to confirm with ground-based telescopes, and other methods of validation are required.

Is there a way to handle the "cracked-piñata" outpouring of Kepler planet candidates?

	Francois Fressin

Francois Fressin (Harvard-Smithsonian Center for Astrophysics) announced new techniques for validating the Kepler planets. He used them to determine that the Kepler 10 system had a second planet, Kepler-10c. Kepler-10b was announced in January 2011, and is the first unquestionably rocky planet discovered. Kepler-10b orbits in less than a day -- it’s a hot rock. Kepler-10c’s orbital period is 45.3 days and is about 2.2 times the diameter of Earth. This planet falls below the detection limit for Doppler studies. Hence, a new method was needed to validate the planet. Fressin discussed a new method, called BLENDER, which distinguishes a transiting planet, from a target star whose light is “blended” with a background eclipsing binary star system (double stars that orbit each other and periodically block out each other's light). The blend of the foreground target star and the background eclipsing binary can produce a signal in the Kepler data, or light curve, that appears to be a transiting planet. BLENDER computes all the possible star and planet configurations and scenarios, and compares the resulting modeled light curves with the actual data. It uses the NASA Ames Research Center’s supercomputer, Pleiades, to make more than 10¹⁵ (a 1 followed be 15 zeros or 1,000,000,000,000,000,000) or a quadrillion calculations to test a transiting planet. For Kepler-10c, the planet was validated using BLENDER as well as NASA's Spitzer Space Telescope, which observed the star system in infrared light. Both methods proved to be a powerful way to conclude that Kepler-10c is 99.98 percent likely to be a planet, and not a chance alignment of a target star with an eclipsing binary. The BLENDER method and Spitzer will be used to validate a large fraction of the Kepler planet finds. BLENDER will be essential to validate the discovery of Earth-size planets on longer orbits; Spitzer may also help, but scientists aren't sure if it will be able to see planets that small. These findings are described in Fressin, et. al, ‘Kepler-10c, a 2.2-Earth radius transiting planet in a multiple system’.
[http://arxiv.org/abs/1105.4647]
See also separate press release.

What is the prevalence of Earth-size planets?

Before Kepler, there was a paucity of small planets because they were hard to find. Today, they appear to be the most common, based upon just the first few months of public Kepler data.

	Geoffrey Marcy, Kepler Co-Investigator.

How do we learn a star’s true age? (without a birth certificate)

	Søren Meibon, Kepler Co-Investigator.

Soeren Meibom, Harvard Smithsonian Center for Astrophysics, is studying the stars, not the exoplanets, in the Kepler field of view. There is a bounty of data pouring down from Kepler, providing exquisitely precise measurements of star systems. Hundreds of astronomers are studying the data to better understand stars. Much can be discovered about the birth, life and death of stars. The large number of scientific publications by the Kepler science team and scientific community on stellar astrophysics substantiates this: 73% (48 of the 66 papers) since February.

Meibom pointed out that if we are seeking evidence of habitable planets -- suitable places for life -- we have to understand the age of the planetary systems to get a sense about whether life has had enough time to evolve. The parent star and its planet share the same birthday, but Meibom explained, “Stars -- and planets -- don’t have birth certificates. They look much the same for almost all of their lives.” He’s conducting a study of the stellar clusters in the Kepler field to develop a better method of determining the age of stars. Stars are spotted, and their spin rates reflect their age: young stars spin rapidly, and older stars -- like the Sun -- spin more slowly. The spin rate of a star can be calculated from the Kepler data, but before this spin rate can be correlated with a good estimate of the star's age, studies must be done on stars with ages that are known from previous studies. That's why Meibom's observations of star clusters with known ages are important. They are helping to establish a firm connection between a star's spin rate and age, creating a sort of clock for determining the age of stars -- and their planets. Meibom presented his first analysis in “The Kepler Cluster Study: NGS 6811”.
[http://arxiv.org/abs/1104.2912]
See also separate press release.

	Photo of NGC6811 by Anthony Ayiomamitis

Scientists are presenting 50 papers, posters, and plenary talks based on Kepler data at the conference. The team has been tweeting and posting live from the invited talks, plenaries, and sessions from the event.

You may view the May 23rd press event "NASA's Kepler Mission: A Progress Report" (also on Archived AAS Press-Conference Webcasts)