Related Experiment Video
Updated: Nov 6, 2025
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
10.6K
The Formation of Bilobate Comet Shapes through Sublimative Torques
Taylor K Safrit1, Jordan K Steckloff1,2,3, Amanda S Bosh1
1Massachussetts Institute of Technology, Cambridge, MA.
The Planetary Science Journal
|May 7, 2021
Summary
Most short-period comets have a unique bilobate shape due to sublimation-driven rotational disruption. This process, unique to comets, explains their distinctive two-lobed structure as they migrate through the solar system.
Area of Science:
- Planetary Science
- Cometary Science
- Solar System Dynamics
Background:
- Approximately 70% of short-period comet nuclei, primarily Jupiter-family comets (JFCs), exhibit bilobate shapes, unlike asteroids of comparable size.
- This prevalence of bilobate shapes in comets suggests a unique formation mechanism distinct from asteroid shape evolution.
Purpose of the Study:
- To investigate the formation mechanism behind the bilobate shapes observed in Jupiter-family comet nuclei.
- To determine if sublimative activity during cometary migration can naturally produce these distinctive shapes.
Main Methods:
- Modeling the torques generated by volatile sublimation during the dynamical migration of comet nuclei.
- Simulating the rotational disruption and subsequent reformation of comet nuclei with known material properties.
Main Results:
- Sublimative activity during migration can spin comet nuclei to the point of rotational disruption.
- The rubble-pile nature of comet nuclei causes them to reform into bilobate shapes after disruption.
- JFCs likely underwent rotational disruption events before entering the Jupiter family, explaining their common bilobate morphology.
Conclusions:
- The bilobate shapes of JFC nuclei are a natural consequence of sublimation-induced rotational disruption during their migration.
- These shapes likely formed recently in cometary history (within the last 1-10 million years), not during initial solar system formation.
Related Concept Videos
01:20Bending and Torsional Moments
4.8K
Bending and torsional moments are two fundamental concepts in structural engineering. They play an important role in understanding the behavior of materials and structures under different loading conditions.
The reaction developed in a structural element when subjected to an external force causes the element to bend. When a structural element bends upwards, it creates compressive normal forces on the top and tensile normal forces on the bottom, resulting in a couple that determines the bending...
The reaction developed in a structural element when subjected to an external force causes the element to bend. When a structural element bends upwards, it creates compressive normal forces on the top and tensile normal forces on the bottom, resulting in a couple that determines the bending...
4.8K
01:25Coplanar Forces
4.9K
Consider an object upon which multiple forces are acting. If the lines of action of each force lie within the same plane, the system can be considered coplanar. The Cartesian vector form can be used to resolve each force into its respective components. For a coplanar system, the system will be in equilibrium if each component of the resultant force equals zero and the resultant force on the system is zero. If the sum of the forces is not equal to zero, then the object will not be in equilibrium...
4.9K
01:11Formation of Higher-order Actin Filaments
3.2K
The polymerization of G-actin monomers into filamentous F-actin is a multi-step process. Once the F-actins are formed, they can bundle together in different arrangements to form higher-order networks and regulate cellular functions. Common examples include the formation of lamellipodia and filopodia at the cell's leading edge by actin reorganization in a migrating cell. The microvilli on the brush border epithelial cells are also formed through the F-actin network.
The high-order actin...
The high-order actin...
3.2K
01:27Toroids
3.4K
A toroid is a closely wound donut-shaped coil constructed using a single conducting wire. In general, it is assumed that a toriod consists of multiple circular loops perpendicular to its axis.
When connected to a supply, the magnetic field generated in the toroid has field lines circular and concentric to its axis. Conventionally, the direction of this magnetic field is expressed using the right-hand rule. If the fingers of the right hand curl in the current direction, the thumb points in...
When connected to a supply, the magnetic field generated in the toroid has field lines circular and concentric to its axis. Conventionally, the direction of this magnetic field is expressed using the right-hand rule. If the fingers of the right hand curl in the current direction, the thumb points in...
3.4K
01:15Torque Free Motion
622
The torque-free motion refers to the movement of a rigid body in space when no external torques are acting upon it. This type of motion can be observed in environments where there are no external forces or frictions, like in outer space. For example, a rotation of Mars in space is a torque-free motion. Mars is an axisymmetric object, meaning it has an axis of symmetry along which it rotates, designated as the z-axis. The rotating frame of reference is defined such that the center of mass of...
622
01:16Torsion of Noncircular Members
306
Circular shafts undergoing torsional stress maintain their cross-sectional integrity due to their axisymmetric nature. This symmetry ensures an even distribution of stress, allowing the shaft to withstand torsion without distorting. In contrast, square bars, lacking this axial symmetry, experience significant distortion across their cross-sections when subjected to torsion, with the exception of along their diagonals and at lines connecting midpoints. A detailed examination of a cubic element...
306