Kepler Planet Candidate Count – 2321

Kepler Planet Candidates
Histogram of Kepler Space Telescope Planet Candidates By Size
Image Credit: NASA Ames / Wendy Stenzel

NASA has now released the third catalog featuring all the candidate planets discovered by the Kepler Space Telescope. This catalog contains 2321 candidates found during observations between May 2009 to September 2010. The histogram above summarizes the findings in the 27 February 2012 Kepler Planet Candidate catalog release by size.

The summary:

  • Confirmed Planets: 61
  • Planet Candidates: 2,321
  • Eclipsing Binary Stars: 2,165

The first 43 days of Kepler data was released in June 2010 and has 312 candidate planets (Borucki et al, 2010). The second release (Borucki et al, 2011) covered the first 13 months of data and was released in February 2011. It contains 1,235 candidate planets.

The third catalog contains 2,321 planet candidates identified during the first 16 months of observation. 46 planet candidates orbit within the habitable zone (liquid water) and ten of them are near Earth size.

Planets are identified by measuring the brightness of more than 150,000 stars. Planets that pass in front of a star (“transit”) cause the light to dim slightly. Candidates are considered possible if Kepler detects three transits.

The artist’s rendering below depicts the multiple planet systems discovered by NASA’s Kepler mission. Prior to the third catalog, scientists had verified six systems with multiple transiting planets (shown t the left in red).

Kepler’s observations have verified planets in 11 new planetary systems (shown to the right in green). Many of these systems contain additional planet candidates that are yet to be verified (shown here in dark purple).

For reference, the eight planets of the solar system are shown in blue (far left).

Real Planets
Confirmed Planetary Systems Found from Kepler Data
Image Credit: NASA Ames / Jason Steffen, Fermilab Center for Particle Astrophysics

Earth Like Planet – Kepler 22b

Kepler 22b
Planet Kepler 22b Orbiting a G-Type Sun 600 Light Years from Earth
Image Credit: NASA / Ames / JPL-Caltech

NASA announced the discovery of an Earth-like planet located 600 light years from Earth. “Just a stroll to the local gas station for a candy bar” compared to the size of the Milky Way galaxy we inhabit.

Kepler 22b
Kepler 22 System and the Inhabitable Zone
Image Credit: NASA / Ames / JPL-Caltech


NASA has announced that the Kepler Mission has released the first 43 days of science data on more than 156,000 stars.

Kepler is designed to continuously monitor a star field in the constellations Cygnus and Lyra. The objective is to find Earth like planets circling solar-like stars in what is known as the Habitable Zone, the region around a star where water can exist as a liquid. Since planetary orbits in this region take about a year to complete, the Kepler mission is designed to last through November 2012. This will allow Kepler to catch a planet fitting the description making three transits of its star during the three and a half year mission. Kepler was launched 6 March 2009.

When a planet transits a star, it blocks some of the light from the star. If an observatory is looking at the star at just the right moment, it will see the star dim and then brighten again when the planet finishes passing in front of the star. The effect is very small. A transit will dim the starlight by 100 parts per million, and last from 2 to 16 hours if the planet is in the habitable zone.

Kepler is designed to monitor 100,000 stars continuously for three and a half years. This is enough time to capture three transits by a planet. Kepler has only one instrument on board. This is a 0.95 meter telescope equipped with a photometer. The telescope has a large field of view in order to capture all the stars simultaneously. The field of view is about the size of your hand held at arms length (105 square degrees).

Data from the Kepler mission is archived at Space Telescope Science Institute. The three missions in which the Institute participates are Hubble, the James Webb Space Telescope, and Kepler.

Kepler Diagram
Diagram of the Kepler Spacecraft
Image Credit: NASA

Kepler Photometer
Kepler Photometer Focal Plane Assembly
Image Credit: Ball Aerospace

The photometer (left) is a single instrument, composed of 42 Charge Coupled Devices (CCDs). Each of the square units in the image are two 25 mm x 50 mm CCDs, each comprised of 2200×1024 pixels.

The CCDs are read every three (3) seconds and the data is integrated over 30 minutes. The instrument has the ability to detect an earth sized object transiting a star in 6.5 hours of integrated data.

The instrument has a spectral bandpass from 400 nm to 850 nm. Data from the individual pixels that make up each star of the 100,000 main-sequence stars are recorded continuously and simultaneously. The data are stored on the spacecraft and transmitted to the ground about once per month.

The targeted region of space and the star field in the field of view can be seen here.

At right is the Kepler spacecraft during construction. The size of the Solar Array and the Telescope (wrapped in gold foil) can be seen compared to the technician working on the Solar Array.

The scientific objective of the Kepler Mission is to explore the structure and diversity of planetary systems. This is achieved by surveying a large sample of stars to:

  • Determine the percentage of terrestrial and larger planets that are in or near the habitable zone of a wide variety of stars
  • Determine the distribution of sizes and shapes of the orbits of these planets
  • Estimate how many planets there are in multiple-star systems
  • Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets
  • Identify additional members of each discovered planetary system using other techniques
  • Determine the properties of those stars that harbor planetary systems

Kepler with Solar Array (interior)
Image Credit: NASA and Ball Aerospace

Let us know what you think. What do you want to know about? Post a comment.