Scott Sheppard studies the dynamical and physical properties of small bodies in our Solar System, such as asteroids, comets, moons and trans-neptunian objects (bodies that orbit beyond Neptune).  These objects have a fossilized imprint from the formation and migration of the major planets in our Solar System, which allow us to understand how the Solar System came to be.

The major planets in our Solar System travel around the Sun in fairly circular orbits and on similar planes. However, since the discovery of wildly varying planetary systems around other stars, and given our increased understanding about small, primordial bodies in our celestial neighborhood, the notion that our Solar System has always been so orderly is changing.

To understand solar system evolution in general and how ours came to be, Carnegie’s Department of Terrestrial Magnetism astronomer Scott Sheppard studies the dynamical and physical properties of small bodies, such as asteroids, comets, moons, trans-neptunian objects (bodies that orbit beyond Neptune), and free floating substellar objects. These small bodies in our Solar System have a fossilized imprint from the formation and migration of the major planets in our Solar System.

The known Solar System can be divided into three parts: the rocky planets like Earth, which are close to the Sun; the gas giant planets, which are further out; and the frozen objects of the Kuiper belt, which lie just beyond Neptune's orbit. Beyond this, there appears to be an edge to the Solar System where only one object, Sedna, was known to exist for its entire orbit until Sheppard and colleagues discovered a second object, dwarf planet 2012 VP113. It has a very eccentric orbit that is even more distant than Sedna. Sheppard has determined that the total population of these so called inner Oort cloud objects is likely bigger than the Kuiper Belt and main asteroid belt. Some of these inner Oort cloud objects could rival the size of Mars or Earth.

There are several competing theories for how the inner Oort cloud might have formed, but all require the Solar System to have been in a state vastly different than now since the inner Oort cloud objects are currently decoupled from any known major planet, yet have disturbed inclined, eccentric orbits. Thus the inner Oort cloud is a window into our Solar System's past. Sheppard and colleague are currently obtaining the widest and deepest survey for Solar System objects ever obtained to discover more inner Oort cloud members.

Active asteroids have stable orbits between Mars and Jupiter like other asteroids. However, unlike other asteroids, they sometimes have the appearance of comets, when dust or gas is ejected from their surfaces. The reasons for this loss of material and subsequent tail in active asteroids are unknown, although there are several theories such as recent impacts or sublimation of exposed ices. Sheppard and colleagues discovered an unexpected tail on asteroid 62412, an object which had been known as a typical asteroid for over a decade. Using Magellan Telescopic observations, Sheppard found 62412 to have a very fast rotation. It thus appears the activity in this asteroid is created by rotational fissioning of material off the surface of 62412. Sheppard and colleagues estimate that there are likely about 100 active asteroids in the main asteroid belt, based on their discovery.

Sheppard is also the co-discoverer of the first trailing Neptune Trojan and first high inclination leading Neptune Trojan. Trojans are asteroids that are locked into the same orbital period as a planet but lead or follow the planet by about 60 degrees. At these spots, the gravitational pull of the planet and the Sun combine to lock the asteroids into synchronized orbits with the planet. The presence of high inclination Trojans implies that Neptune was on a much more eccentric orbit in the past. As Neptune went through the process of becoming more circular in orbit, it gained the ability to capture high-inclination objects. Sheppard has also learned that Neptune Trojans share many similarities with their Jupiter counterparts.

In another research area, Sheppard surveys our Solar System for so-called irregular satellites. These bodies have been captured by their respective planets. Regular satellites, on the other hand, were created during disk accretion. Sheppard and colleagues have discovered over 70 of the irregular moons around Jupiter, Saturn, Uranus, and Neptune. During the survey, Sheppard determined that the giant planets all possess about the same number of irregular satellites, despite large differences in planetary mass and formation scenarios.

Sheppard discovered the first contact binary Kuiper belt object. A contact binary contains two objects that are drawn together by tidal friction like the Earth and the Moon to orbit about one another. The large amount of angular momentum in the Kuiper Belt suggests it was much denser in the distant past. Similar observations by Sheppard and his colleagues also yielded one of the first measurements of the bulk density of a KBO; the value is sufficiently low that a volatile-rich, porous structure is indicated.

Sheppard received his B.A. in physics from Oberlin College and his M.S. and Ph. D. from the University of Hawaii, where he was also a teaching assistant and a research assistant. Before becoming a staff scientist at Carnegie in 2007, he was a Carnegie Hubble Fellow. For more see http://dtm.carnegiescience.edu/people/scott-s-sheppard

Explore Carnegie Science

Carnegie Science, Carnegie Institution, Carnegie Institution for Science, ASAS-SN
July 28, 2017

Pasadena, CA— Carnegie’s Benjamin Shappee is part of a team of scientists, including an Australian amateur astronomer, which discovered a new comet last week.

Called the All Sky Automated Survey for Supernovae (ASAS-SN), the international collaboration, which is headquartered at the Ohio State University, uses a network of eight 14-centimeter telescopes around the world to scan the visible sky every two or three nights looking for very bright supernovae.

But this time out they found something else—a comet. 

Jose Prieto, a former Carnegie postdoc now a professor at Universidad Diego Portales in Chile, was the first ASAS-SN team member to notice the bright, moving

Carnegie Science, Carnegie Institution, Carnegie Institution for Science,
July 20, 2017

"The Moon needs no introduction ... To the layman, not versed in astrophysics, the Moon is the most-conspicuous object in the night sky and the rival of all heavenly objects, even including the Sun itself" wrote Carnegie's F.E. Wright in a poetic 1935 paper about the challenges of studying the lunar surface, which was written when the idea of sending humans there was beyond the imagination.

Reporting on the work of a Committee on Study of the Surface Features of the Moon, Wright laid out the challenges of approaching lunar research using the standard techniques employed by geologists of the time—food for thought on the anniversary of the 1969 Moon landing.  

"The observer

Carnegie Science, Carnegie Institution for Science, Carnegie Institution, Max Planck Institute for Astronomy
May 24, 2017

Pasadena, CA— A team of astronomers including Carnegie’s Eduardo Bañados and led by Roberto Decarli of the Max Planck Institute for Astronomy has discovered a new kind of galaxy which, although extremely old—formed less than a billion years after the Big Bang—creates stars more than a hundred times faster than our own Milky Way.

Their findings are published by Nature.

The team’s discovery could help solve a cosmic puzzle—a mysterious population of surprisingly massive galaxies from when the universe was only about 10 percent of its current age.

After first observing these galaxies a few years ago, astronomers proposed that they must have been created from hyper-

May 17, 2017

Former Carnegie fellow and current trustee, astronomer Sandra Faber, has been awarded the 2017 Gruber Foundation Cosmology Prize. She was awarded the lifetime achievement award for “her groundbreaking studies of the structure, dynamics, and evolution of galaxies.” Her work provided the impetus to study dark matter, the invisible material that makes up most of the mass of the universe, in addition to  “ the recognition that black holes reside at the heart of most large galaxies."

Faber also has a long history of contributing to  innovative telescope technology, and she has “aided and inspired the work of astronomers and cosmologists worldwide.”

The prize will be awarded this

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The fund supports a postdoctoral fellowship in astronomy that rotates between the Carnegie Science departments of Terrestrial Magnetism in Washington, D.C., and the Observatories in Pasadena California. 

The Earthbound Planet Search Program has discovered hundreds of planets orbiting nearby stars using telescopes at Lick Observatory, Keck Observatory, the Anglo-Australian Observatory, Carnegie's Las Campanas Observatory, and the ESO Paranal Observatory.  Our multi-national team has been collecting data for 30 years, using the Precision Doppler technique.  Highlights of this program include the detection of five of the first six exoplanets, the first eccentric planet, the first multiple planet system, the first sub-Saturn mass planet, the first sub-Neptune mass planet, the first terrestrial mass planet, and the first transit planet.Over the course of 30 years we have improved the

The Giant Magellan Telescope will be one member of the next class of super giant earth-based telescopes that promises to revolutionize our view and understanding of the universe. It will be constructed in the Las Campanas Observatory in Chile. Commissioning of the telescope is scheduled to begin in 2021.

The GMT has a unique design that offers several advantages. It is a segmented mirror telescope that employs seven of today’s largest stiff monolith mirrors as segments. Six off-axis 8.4 meter or 27-foot segments surround a central on-axis segment, forming a single optical surface 24.5 meters, or 80 feet, in diameter with a total collecting area of 368 square meters. The GMT will

Along with Alycia Weinberger and Ian Thompson, Alan Boss has been running the Carnegie Astrometric Planet Search (CAPS) program, which searches for extrasolar planets by the astrometric method, where the planet's presence is detected indirectly through the wobble of the host star around the center of mass of the system. With over eight years of CAPSCam data, they are beginning to see likely true astrometric wobbles beginning to appear. The CAPSCam planet search effort is on the verge of yielding a harvest of astrometrically discovered planets, as well as accurate parallactic distances to many young stars and M dwarfs. For more see  http://instrumentation.obs.carnegiescience.edu/ccd/caps.

Guillermo Blanc wants to understand the processes by which galaxies form and evolve over the course of the history of the universe. He studies local galaxies in the “present day” universe as well as very distant and therefore older galaxies to observe the early epochs of galaxy evolution. Blanc conducts a series of research projects on the properties of young and distant galaxies, the large-scale structure of the universe, the nature of Dark Energy—the mysterious repulsive force, the process of star formation at galactic scales, and the measurement of chemical abundances in galaxies.

To conduct this work, he takes a multi-wavelength approach including observations in the UV,

Peter van Keken studies the thermal and chemical evolution of the Earth. In particularly he looks at the causes and consequences of plate tectonics; element modeling of mantle convection,  and the dynamics of subduction zones--locations where one tectonic plate slides under another. He also studies mantle plumes; the integration of geodynamics with seismology; geochemistry and mineral physics. He uses parallel computing and scientific visualization in this work.

He received his BS and Ph D from the University of Utrecht in The Netherlands. Prior to joining Carnegie he was on the faculty of the University of Michigan.

Peter Driscoll studies the evolution of Earth’s core and magnetic field including magnetic pole reversal. Over the last 20 million or so years, the north and south magnetic poles on Earth have reversed about every 200,000, to 300,000 years and is now long overdue. He also investigates the Earth’s inner core structure; core-mantle coupling; tectonic-volatile cycling; orbital migration—how Earth’s orbit moves—and tidal dissipation—the dissipation of tidal forces between two closely orbiting bodies. He is also interested in planetary interiors, dynamos, upper planetary atmospheres and exoplanets—planets orbiting other stars. He uses large-scale numerical simulations in much of his research

Andrew Newman works in several areas in extragalactic astronomy, including the distribution of dark matter--the mysterious, invisible  matter that makes up most of the universe--on galaxies, the evolution of the structure and dynamics of massive early galaxies including dwarf galaxies, ellipticals and cluster. He uses tools such as gravitational lensing, stellar dynamics, and stellar population synthesis from data gathered from the Magellan, Keck, Palomar, and Hubble telescopes.

Newman received his AB in physics and mathematics from the Washington University in St. Louis, and his MS and Ph D in astrophysics from Caltech. Before becomming a staff astronomer in 2015, he was a