Help Shape the Future of Space Exploration

Join The Planetary Society Now  arrow.png

Join our eNewsletter for updates & action alerts

    Please leave this field empty
Multimedia IconMultimedia

Planet 9 From Outer Space!

Planet 9

Air Date: 02/09/2016
Run Time: 49:10

Listen to the full show:

Or Download mp3


  • Mike Brown, Planetary Astronomer, California Institute of Technology
  • Konstantin Batygin, Assistant Professor of Planetary Science, California Institute of Technology

Topics: obituary, Planetary Society Projects, astronomy, LightSail, the Moon, Chang'E program, Bill Nye

Support Planetary Radio

Mike Brown and Konstantin Batygin fully expect a new and undemotable ninth planet will be found in the outer reaches of the solar system. The Caltech researchers talk about their findings and much more. Emily Lakdawalla has made a wealth of Chinese lunar lander images much more accessible. Have gravity waves been discovered? Bill Nye hopes so, as he also remembers Apollo 14 moonwalker Edgar Mitchell.

Planet 9

Caltech / R. Hurt (IPAC)

Planet 9
Artistic rendering of Planet 9 with the distant Sun in the background.
Mike Brown and Konstantin Batygin

Mat Kaplan

Mike Brown and Konstantin Batygin
Planet 9 theorists Mike Brown and Konstantin Batygin study the data in Mike’s Caltech office.

Related Links:

Trivia Contest

This week's prizes are a lovely Planetary Radio t-shirt, a 200-point astronomy account AND a set of Year In Space wall and desk calendars.

This week's question:

What was famous astronomer Herschel’s first and middle names?

To submit your answer:

Complete the contest entry form at or write to us at no later than Tuesday, February 16th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

In Earth days, how long is a Pluto day (as well as a Charon day)?


The answer will be revealed next week.

Question from the week before:

Where in the solar system is Anthony Patera?


Anthony Patera is both a shallow depression on Venus that honors Susan B. Anthony and a distinguished professor at MIT.


No trivia contest spoilers please!

sepiae: 02/09/2016 08:52 CST

'Undemotable', wonderful :) - 'Planet 9: this time it's UNDEMOTABLE!' - And it's name is gonna *be* Rupert. Period.

Bryan See: 02/09/2016 11:28 CST

That was the appearance of Caltech astronomer Mike Brown in less than eight months. Congratulations on your findings and more you talk along with Konstantin Batygin. Mike Brown, you are a celebrity astronomer, and I hope that you will appear on the TV show, The Big Bang Theory, and several late night talk shows such as The Tonight Show with Jimmy Fallon. Bravo.

sepiae: 02/17/2016 09:22 CST

Apart from my enthusiasm for my fav name for P9 (in honor to the late great D.N. Adams) I should mention that the interview rocks. Very comprehensive, informative and also fun! Both chaps are the kind to hang out with, for these qualities. Wonderful work, and congrats from me as well!

MaxB1938: 11/05/2016 07:37 CDT

Perhaps the Great Red Spot on Jupiter was caused by it swallowing planet 9.

Leave a Comment:

You must be logged in to submit a comment. Log in now.
Facebook Twitter Email RSS AddThis

Planetary Radio Search

Planetary Defense

An asteroid or comet headed for Earth is the only large-scale natural disaster we can prevent. Working together to fund our Shoemaker NEO Grants for astronomers, we can help save the world.


Space in Images

Pretty pictures and
awe-inspiring science.

See More

Join The Planetary Society

Let’s explore the cosmos together!

Become a Member

Connect With Us

Facebook, Twitter, YouTube and more…
Continue the conversation with our online community!