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Briefing Materials: Artificial Intelligence and NASA Data Used to Discover Eighth Planet Circling Distant Star

NASA will host a media teleconference at 1 p.m. EST Thursday, Dec. 14, to announce the latest discovery made by its planet-hunting Kepler space telescope. The discovery was made by researchers using machine learning from Google. Machine learning is an approach to artificial intelligence, and demonstrates new ways of analyzing Kepler data.

Teleconference audio and visuals will stream live at:

The briefing participants are:

  • Paul Hertz, Astrophysics Division director at NASA Headquarters in Washington
  • Christopher Shallue, senior software engineer at Google AI in Mountain View, California
  • Andrew Vanderburg, astronomer and NASA Sagan Postdoctoral Fellow at The University of Texas, Austin
  • Jessie Dotson, Kepler project scientist at NASA’s Ames Research Center in California’s Silicon Valley

NASA will host a Reddit Ask Me Anything at 3 p.m. EST today on this discovery.

NASA Media Advisory
NASA Media Teleconference Audio File and Transcript
NASA Press Release
Short Video – Artificial Intelligence and NASA Data Used to Discover Eighth Planet Circling Distant Star

Figure 1

An illustration of the different elements in NASA’s exoplanet program
This is an illustration of the different elements in NASA’s exoplanet program, including ground-based observatories, like the W. M. Keck Observatory, and space-based observatories, like Hubble, Spitzer, Kepler, Transiting Exoplanet Survey Satellite, James Webb Space Telescope, Wide Field Infrared Survey Telescope and future missions.
Credits: NASA

Figure 2

When a distant exoplanet transits, or crosses in front of its star, it causes a slight dip in the star’s brightness. The Kepler space telescope measures this dip in a star’s brightness over time. The U-shaped pattern that emerges is a signal of the presence of a planet as shown by the solid white line. The scatter plot (colored blue) is representative of the recorded data.

Figure 3

Animated gif explaining how a computer can learn to identify a dog from a cat
A neural network is a technique of machine learning that is loosely inspired by the structure of the human brain in which “neurons” do a simple computation and then pass information to the next layer of neurons. In this way, a computer can “learn” how to identify a dog from a cat, or an exoplanet from something else in the light readings measured by space telescopes like Kepler.
Credits: Google

Figure 4

The Kepler space telescope has produced more than 30,000 signals of possible planets circling distant stars. Researchers taught a computer to “learn” how to identify the weak signals of a planet crossing its star using a neural network. A search for new worlds around 670 known multiple-planet systems using this machine-learning technique yielded not one, but two discoveries: Kepler-90i and Kepler-80g.

Figure 5

Kepler-90 system planet sizes, compared to planets in our solar system
The Kepler-90 planets have a similar configuration to our solar system with small planets found orbiting close to their star, and the larger planets found farther away. In our solar system, this pattern is often seen as evidence that the outer planets formed in a cooler part of the solar system, where water ice can stay solid and clump together to make bigger and bigger planets. The pattern we see around Kepler-90 could be evidence of that same process happening in this system.
Credits: NASA/Ames Research Center/Wendy Stenzel
Kepler-90 System Planet Sizes

Figure 6

Kepler-90 system planet orbits, compared to planetary orbits in our solar system
Kepler-90 is a Sun-like star, but all of its eight planets are scrunched into the equivalent distance of Earth to the Sun. The inner planets have extremely tight orbits with a “year” on Kepler-90i lasting only 14.4 days. In comparison, Mercury’s orbit is 88 days. Consequently, Kepler-90i has an average surface temperature of 800 degrees Fahrenheit, and is not a likely place for life as we know it. The structure of the Kepler-90’s system hints that the eight planets around Kepler-90 may have formed more spread out, like the planets in our own solar system, and then somehow migrated to the orbits we see them in today.
Credits: NASA/Ames Research Center/Wendy Stenzel
Kepler-90 Planets Orbit Close to Their Star

Figure 7

Graphic showing the relatively small area of the Kepler-90 system that has been searched by Kepler
This graphic shows that a small area around the Kepler-90 system, on the left, has been searched by the Kepler space telescope. Compared to our solar system, where we know of planets farther out, it is possible that Kepler-90 has even more planets. If planets (in the blue area) do exist, they probably would not have transited enough times while Kepler was watching for us to know they were there.
Credits: NASA/Ames Research Center/Wendy Stenzel
Could Kepler-90 Have More Planets?

Figure 8

This figure shows the number of systems with one, two, three, planets, etc.
This figure shows the number of systems with one, two, three, planets, etc. Each dot represents one known planetary system. We know of more than 2,000 one-planet systems, and progressively fewer systems with many planets. The discovery of Kepler-90i, the first known exoplanet system with eight planets, is a hint of more highly populated systems to come.
Credits: NASA/Ames Research Center/Wendy Stenzel and The University of Texas at Austin/Andrew Vanderburg
Planetary Systems by Number of Known Planets

Figure 9

Graph showing number and size of exoplanets discovered before 2009.
When the Kepler Space Telescope launched in 2009, we knew of 326 planets beyond the solar system, most of which were similar in size to Jupiter, and all much larger than Earth.
Credits: NASA/Ames Research Center/Jessie Dotson and Wendy Stenzel

Figure 10

Graph showing 3,567 current confirmed exoplanets
Today, as shown in figure 10, we know of over 3,500 confirmed exoplanets, with more than 2,500 of those found in the Kepler data. These planets range in size from larger than Jupiter to smaller than Earth. In just a couple decades, thanks largely to Kepler, we have gone from suspecting exoplanets existed to knowing that there are more exoplanets than stars in our galaxy.
Credits: NASA/Ames Research Center/Jessie Dotson and Wendy Stenzel
Exoplanet Discoveries