The Search for Planet X/Planet 9 in the Outer Solar System Discovers New Distant Objects
This work was partially funded by NASA.
This project used data obtained with DECam, which was constructed by
the Dark Energy Survey collaborating institutions.
Observations were partly obtained at Cerro Tololo Inter-American
Observatory, National Optical Astronomy Observatory, operated by the
Foundation of Universities for Research in Astronomy, under contract
with the National Science Foundation.
This paper includes data gathered with the Carnegie 6.5 meter Magellan
Telescopes located at Las Campanas Observatory, Chile.
Scott S. Sheppard
Carnegie Institution for Science
5241 Broad Branch Rd. NW
Washington, DC 20015
email: ssheppard at carnegiescience.edu (replace "at" with "@")
In the race to discover a proposed ninth planet in our Solar System,
Carnegie's Scott Sheppard and Chadwick Trujillo of Northern Arizona
University have observed several never-before-seen objects at extreme
distances from the Sun in our Solar System. Sheppard and Trujillo have
now submitted their latest discoveries to the International
Astronomical Union's Minor Planet Center for official designations. A
paper about the discoveries has also been accepted to The Astronomical
The more objects that are found at extreme distances, the better the
chance of constraining the location of the ninth planet that Sheppard
and Trujillo first predicted to exist far beyond Pluto in 2014.
The placement and orbits of small, so-called extreme trans-Neptunian
objects, can help narrow down the size and distance from the Sun of
the predicted ninth planet, because that planet's gravity influences
the movements of the smaller objects that are far beyond Neptune. The
objects are called trans-Neptunian, because their orbits around the
Sun are greater than Neptune's.
In 2014, Sheppard and Trujillo announced the discovery of 2012 VP113
(nicknamed "Biden"), which has the most distant known orbit in our
Solar System. At this time, Sheppard and Trujillo also noticed that
the handful of known extreme trans-Neptunian objects all cluster with
similar orbital angles. This lead them to predict that there is a
planet at more than 200 times our distance from the Sun, whose mass
ranging in possibility from several Earths to a Neptune equivalent is
shepherding these smaller objects into similar types of orbits.
Some have called this Planet X or Planet 9. Further work since 2014
showed that this massive ninth planet likely exists by further
constraining its possible properties. Analysis of "neighboring" small
body orbits suggest that it is several times more massive than the
Earth, possibly as much as 15 times more so, and at the closest point
of its extremely stretched, oblong orbit it is at least 200 times
farther away from the Sun than Earth. (This is over 5 times more
distant than Pluto.)
"Objects found far beyond Neptune hold the key to unlocking our Solar
System's origins and evolution," Sheppard explained. "Though we
believe there are thousands of these small objects, we haven't found
very many of them yet, because they are so far away. The smaller
objects can lead us to the much bigger planet we think exists out
there. The more we discover, the better we will be able to understand
what is going on in the outer Solar System."
Figure 1: Movie of the discovery images of 2014 SR349 from the
Dark Energy Camera on the NOAO 4-meter Blanco telescope in Chile.
Images are about 3 hours apart on September 19th, 2014. 2014 SR349
can be seen moving up and down just left of the star near the
center of the image. The stationary objects are the steady state
background of stars and galaxies. One image is more fuzzy than the
other because the Earth's atmosphere became more turbulent between
the images. (Click on Image or HERE to see individual discovery images.)
Sheppard and Trujillo, along with David Tholen of the University of
Hawaii, are conducting the largest, deepest survey for objects beyond
Neptune and the Kuiper Belt and have covered nearly 10 percent of the
sky to date using some of the largest and most advanced telescopes and
cameras in the world, such as the Dark Energy Camera on the NOAO
4-meter Blanco telescope in Chile and the Japanese Hyper Suprime
Camera on the 8-meter Subaru telescope in Hawaii. As they find and
confirm extremely distant objects, they analyze whether their
discoveries fit into the larger theories about how interactions with a
massive distant planet could have shaped the outer Solar System.
"Right now we are dealing with very low-number statistics, so we don't
really understand what is happening in the outer Solar System,"
Sheppard said. "Greater numbers of extreme trans-Neptunian objects
must be found to fully determine the structure of our outer Solar
According to Sheppard, we are now in a similar situation as in the
mid-19th century when Alexis Bouvard noticed Uranus' orbital motion
was peculiar, which eventually led to the discovery of Neptune.
The new objects they have submitted to the Minor Planet Center for
designation include 2014 SR349, which adds to the class of the rare
extreme trans-Neptunian objects. It exhibits similar orbital
characteristics to the previously known extreme bodies whose positions
and movements led Sheppard and Trujillo to initially propose the
influence of Planet X.
Another new extreme object they found, 2013 FT28, has some
characteristics similar to the other extreme objects but also some
differences. The orbit of an object is defined by six parameters. The
clustering of several of these parameters is the main argument for a
ninth planet to exist in the outer solar system. 2013 FT28 shows
similar clustering in some of these parameters (its semi-major axis,
eccentricity, inclination, and argument of perihelion angle, for angle
enthusiasts out there) but one of these parameters, an angle called
the longitude of perihelion, is different from that of the other
extreme objects, which makes that particular clustering trend less
Another discovery, 2014 FE72, is the first distant Oort Cloud object
found with an orbit entirely beyond Neptune. It has an orbit that
takes the object so far away from the Sun (some 3000 times farther
than Earth) that it is likely being influenced by forces of gravity
from beyond our Solar System such as other stars and the galactic
tide. It is the first object observed at such a large distance.
Figure 2: The orbits of the new extreme trans-Neptunian objects
2014 SR349 and 2013 FT28 are shown in yellow. The known extreme
objects are shown in green with the possible orbit of Planet
X/Planet 9 shown in red. The Kuiper Belt is shown by a cyan torus
while the orbits of Neptune, Uranus and Saturn are shown in dark
blue interior to the Kuiper Belt. Though 2014 SR349 has a similar
orbital alignment as the other known extreme objects in its
longitude of perihelion shown here, 2013 FT28 does not. (Click on
Image or HERE to Learn More About the Known Extreme Objects.)
This work was partially funded by NASA. This project used data obtained with DECam, which was constructed by the Dark Energy Survey collaborating institutions. Observations were partly obtained at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, operated by the Foundation of Universities for Research in Astronomy, under contract with the National Science Foundation. This paper includes data gathered with the Carnegie 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.
Scott S. Sheppard Carnegie Institution for Science 5241 Broad Branch Rd. NW Washington, DC 20015 phone 202-478-8854 email: ssheppard at carnegiescience.edu (replace "at" with "@")