The Case of the Missing Planet

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Science follows wherever the clues lead, including entirely new conclusions. 

Produced by the Space Telescope Science Institute, Office of Public Outreach.
Images, Videos, Animations, and Visualizations:
  • Constellation illustrations with sky visualization: NASA/ESA, Digitized Sky Survey, Davide De Martin
  • Hubble image with star Fomalhaut labeled: NASA/ESA and P.Kalas, A. Gáspár, G. Rieke
  • Hubble image, unlabeled: NASA/ESA and P. Kalas, J. Graham, E. Chiang, E. Kite, M. Fitzgerald
  • Spitzer image: NASA/JPL-Caltech, K. Stapelfeldt
  • Hubble image with time-lapse pull out graphic: NASA/ESA, A. Gáspár, G. Rieke
  • Planet orbiting Fomalhaut, animation: ESA, L. Calçada
  • Herschel Space Observatory image (blue): ESA
  • ALMA image (yellow): ESO/NAOJ/NRAO, L. Matrà, M. A. MacGregor
  • Comet collision illustration: ESA, NASA, M. Kornmesser
  • Hubble image fading over time: NASA/ESA, A. Gáspár, G. Rieke
  • Solar System animation: NASA/Goddard Space Flight Center
  • Fomalhaut/sky visualization: ESA, M. Kornmesser; ESO, L.L. Christensen

Writing: Leah Ramsay
Design: Leah Hustak 
Science review lead: Dr. Quyen Hart
Education lead: Timothy Rhue II
Music from APM Music


 Text, where do we fit in all this? 

What is out there? 

How does the universe work? 

The Case of the Missing Planet 

"Eliminate the impossible. Whatever remains, no matter how improbable, must be the truth." Sherlock Holmes 

Like detectives with super high-tech equipment, astronomers gather evidence about the universe. 

New clues lead to new discoveries, sometimes unexpected ones. 

Science follows wherever the clues lead. 

Recently NASA's Hubble Space Telescope gave astronomers a real mystery to solve when a proposed planet orbiting the star Fomalhaut disappeared from view. 

The clues had been accumulating for over a decade. 

Starting in 2004, astronomers used Hubble's coronagraph to block the brilliant light of the star Fomalhaut and were able to detect a small, bright area of interest. 

Though the images were fuzzy, it was exciting to think of Hubble directly detecting visible light from a planet outside our solar system. 

However, clues from another telescope made the case more complicated. 

A planet with the mass to shape Fomalhaut's ring should glow brightly with infrared light. 

However, NASA's infrared Spitzer Space Telescope observed the area and did not detect a planet. 

The case was open. What could explain the clues? 

Over time, Hubble showed the object in orbit, but dimming. 

Could it be surrounded by a large amount of dust? 

This still would not account for a massive planet without an infrared signature. 

ESA's Herschel Space Observatory and the ALMA radio telescope show evidence that frequent comet collisions had created the dusty ring around Fomalhaut. 

Could the bright object seen by Hubble have been the result of a recent, massive collision? 

Astronomers calculate the chances of witnessing such a massive collision in Fomalhaut's ring are very small: 1 in 200,000. 

Yet researchers' calculations matched up with Hubble's observations over the years. 

Over time the dust cloud spread out until it was no longer detectable. 

Scientists think they got lucky, with Hubble pointed at the right place at the right time to observe the rare collision. 

The Fomalhaut system appears to be at a stage similar to the early days of our own solar system. 

Remnants from that time are found beyond Neptune in the Kuiper Belt, a ring of dust and rocky objects smaller than planets. 

Astronomers will continue to study Fomalhaut and follow whatever evidence they find. 

There could still be an orbiting planet that has not yet been detected, as well as clues to the history of planet formation in our own cosmic neighborhood.