How Far? Far Far Out

Chad Trujillo stands in front of a computer monitor showing an image of space with a red circle around a new object that he has discovered with fellow astronomer Scott Sheppard named FarFarOut.

There’s a new distance champion in the cosmic race around the sun.

Late last month, a team of astronomers including Northern Arizona University’s Chad Trujillo, the University of Hawaii’s David Tholen and Scott Sheppard of the Carnegie Institution for Science discovered an object they have named “FarFarOut” in reference to “FarOut,” their previous distance champ.

FarFarOut is located at approximately 140 astronomical units (AU), or 140 times the distance between the Earth and the sun. The new discovery has exceeded FarOut by 20 AU.

The team discovered the two objects in their search for what they call “Planet X,” a theoretical planet at the edge of our solar system that could be even larger than Earth, Trujillo said. (It is sometimes called “Planet 9,” often by those who do not consider Pluto the ninth planet.)

Trujillo said two such record-breaking discoveries within a few months of each other is unusual, but discoveries of distant solar system objects is not.

Scientific American magazine reported that Trujillo and Scott have discovered 62 objects in their search for Planet X, accounting for 80 percent of all those known beyond 60 AU. Pluto averages 40 AU throughout its orbit.

While Sheppard waited out a snowstorm that delayed a presentation on Planet X in Washington D.C., he reviewed images captured in January with the Subaru telescope in Hawaii. He found FarFarOut at a just-detectable level.

When the presentation occurred a day later, Sheppard shared his “hot off the presses” discovery of this extremely distant object hidden among an image of luminous galaxy clusters and other solar system objects.

The object’s distance is all the astronomers know about it so far. In the last two weeks, Sheppard visited the Giant Magellan Telescope in Chile, while Trujillo remotely used the Victor M. Blanco Telescope’s Dark Energy Camera in the hopes of catching another glimpse of FarFarOut.

Trujillo said that when such an object is discovered, the distance and brightness are known almost immediately, but details about the surface and orbit could take years to determine, especially for objects with orbits that take up to 10,000 years to complete.

Four months after the discovery of FarOut, not much more is known about this object either, except that it is about 500 kilometers in diameter, likely spherical in shape and its pinkish color probably means it is covered in ice, Carnegie Science reported.

Although FarFarOut is by no means the most distant object astronomers have found in space, or the one with the largest orbit, its current position is the farthest place astronomers have found such an object traveling around our sun the way the planets do.

If this point, at 140 AU, is the closest or farthest part of FarFarOut’s orbit remains to be seen.


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The hunt for Planet X began in 2014, when the team first proposed its existence with a model that, if reinforced by the discovery of this planet, would revolutionize solar system studies.

Planet X would exist in the case that all the giant planets formed closer together than they are today, Sheppard said in his presentation. In a fight for space and resources, though, these planets gradually spread out and Planet X was tossed into the outer solar system, becoming what Sheppard calls “the runt of the family.”

Trujillo said, “For generations, we’ve been thinking there are eight big planets. To think there could be another big planet out there really pushes the boundary of what we think our solar system is.”

The team spends extra time working with large telescopes like the Subaru and Magellan from November to January every year because they believe Planet X will be located in the winter sky, where some of the most distant objects have been uncovered, including both FarOut and FarFarOut.

Trujillo compared this process to an Easter egg hunt. Although the team searches wherever it can to find potential treasures, if a large group of eggs is found in one area – like distant objects are in the winter sky – it must mean more are nearby.

Now the team will have several months to go through the data they collected to see if they documented anything interesting, like FarFarOut.

For now, Trujillo said FarFarOut’s coordinates will be submitted to the Minor Planet Center, allowing others to help determine its orbit and other qualities.

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Kaitlin Olson can be reached at the office at kolson@azdailysun.com or by phone at (928) 556-2253. 


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