Strange Planets

A maglite star-planet model for showing

how a star can be made to appear to wobble

from the gravitational influence of a planet.

Show Description: This show, first announced in the March issue of The Planetarian in the article Share the Hunt for Other Earths, (A. Gould, T. Komatsu, E. DeVore, P. Harman, D. Koch), is NOT a prerecorded/prerendered program for fulldome systems, but we do present the program here at LHS live with the fulldome system we have. This show is available as a free download.

It is designed as live audience participation program, about 50-minutes long, but is modular, and as such can be adjusted for shorter lengths. Current version is presented at LHS for public audiences, best for ages 8-adult.

The show (50 min version) has the following sections:

    1. Introduction (5 min): Pose the context-setting questions: Are we alone? Do you think there might be other life out there? Hundreds of planets outside our solar system have already been discovered.

    2. Spectroscopic Method (10 min): Demo spectrum from a flashlight fitted with diffraction grating, then a star-planet demonstration/model of how gravity of an extrasolar planet causes a star to wobble, which in turn causes shifting spectral lines (the Doppler shift). How much a star wobbles depends on the mass of extrasolar planet(s) going around it and how fast a star wobbles is an indicator of how close it is to its star and hence how high its temperature is.

    3. Stars with Planets (5 min): Show two very easy-to-find stars with planets: Pollux (binary star in Gemini) and Alrai (orange star in Cepheus). Audience considers what it might be like to live on a "strange" planet, e.g. one with a binary star or an orange star.

    4. Kepler's Laws and Habitable Zones (5 min): Audience learns that a habitable planet is one that has temperature and conditions for liquid water; that planet orbits are oval or elliptical in shape (Kepler's 1st Law) and that how quickly a planet orbits its star depends on how close it is to its star, in accord with Kepler's 2nd and 3rd Laws.

    5. Transiting Planets (10 min): Use a 2-planet orrery, light sensor and graphing software to demonstrate how brightness changes can be used in finding extrasolar planets--observing transits where a planet periodically blocks starlight, even though the planet is not visible. The audience sees the size of a planet is directly related to that amount of starlight it blocks and that how often starlight is blocked is related to how close a planet is to its star, thereby inferring the planet temperature and habitability.

    6. Finding an Earth-like Exoplanet (10 min): Audience studies simulated light curves to find pattern of an Earth-size in the habitable zone of its star.

    7. Kepler Star Field/Conclusion (5 min): Conclude with more specifics about the NASA Kepler Mission, including where in the sky its target regions of study is.

Strange Planets was field-tested at 5 planetariums and

the final version revised based on field-test feedback.


News/Updates for PASS: Strange Planets

Free Download:

As of May 2014, this show, updated for use in digital planetariums, is now available as a complete electronic package, which includes the show script and all media, including images, movies and audio.

More animations and movies may be found in the multimedia area of the Kepler Mission website.

For questions regarding content, e-mail Alan Gould


If you have installed and presented Strange Planets, please let us know how it went through our Strange Planets feedback form online:


The NASA Kepler EPO team at Lawrence Hall of Science (LHS) and

SETI Institute collaborated with NASA Astrobiology Institute (NAI) and

the Pacific Science Center (PSC) to produce this audience-participation planetarium show.

Strange Planets was produced by the Lawrence Hall of Science PASS project

with funding from NASA's Kepler Mission Education and Public Outreach