Tracking Evolution in the Asteroid Belt

Between the orbits of Mars and Jupiter lies a large concentration of asteroids, which are conglomerates of rock and ice that hold clues to the formation of our solar system. This ‘Asteroid Belt’ is the rubble left over from the construction of our solar system, and Hubble’s observations have helped shape our understanding of their interactions and compositions.

P/2013 R3 on November 15, 2013.
NASA, ESA, and D. Jewitt (UCLA)
A Fragmented Asteroid
Hubble watched the slow disintegration of asteroid P/2013 R3 into 10 smaller pieces. The Hubble data revealed that the fragments are drifting away from each other at a leisurely one mile per hour — slower than the speed of a strolling human — which suggests the breakup is not the result of a collision.

This video, assembled from a series of Hubble images, reveals the breakup of asteroid P/2013 R3 over a period of several months starting in late 2013. The largest fragments are up to 180 meters (200 yards) in radius, each with "tails" caused by dust lifted from their surfaces and pushed back by the pressure of sunlight. The ten pieces of the asteroid drift apart slowly and show a range of breakup times, suggesting that the disintegration cannot be explained by a collision with another asteroid. One idea for the breakup is that the asteroid was accelerated by sunlight to spin at a fast enough rate to fly apart by centrifugal force. The images were taken in visible light with Hubble's Wide Field Camera 3.

An odd, X-shaped debris field trailing dusty streamers is likely the remnants of an asteroid collision. Scientists think that a small, fast-moving asteroid blasted into a larger and slower-moving one.
NASA, ESA, and D. Jewitt (UCLA)
Asteroid Collisions
Astronomers using Hubble witnessed the impact of two asteroids in the asteroid belt. Hubble observations showed a bizarre, X-shaped pattern of filamentary structures near the point-like core of an object with trailing streamers of dust. This complex structure suggested the small body was the product of a head-on collision between two asteroids traveling five times faster than a rifle bullet. The observation helped support the idea that the asteroid belt is slowly eroding through collisions.
Images of asteroid P/2013 P5 revealed its unique dust trails radiating in multiple directions and changing in appearance with time.
NASA, ESA, and D. Jewitt (UCLA)
Asteroid or Comet?
In 2013, Hubble observed an asteroid with six comet-like tails of dust radiating from it like spokes on a wheel. Unlike all other known asteroids, which appear simply as tiny points of light, this asteroid resembles a rotating lawn sprinkler. Computer models of the object suggest the tails may have formed through a series of dust-ejection events.

A Binary Asteroid

Hubble also observed the first known binary asteroid that also looks like a comet. The asteroid duo orbits each other and has a tail of dust like a comet. The asteroid, called 300163 (2006 VW139), likely broke into two pieces some 5,000 years ago due to its fast rotation.

animation of a comet with a shifting tail

This time-lapse video, assembled from a set of Hubble photos, reveals two asteroids orbiting each other that have comet-like features. The asteroid pair, called 2006 VW139/288P, was observed in September 2016, just before the asteroid made its closest approach to the Sun. The photos revealed ongoing activity in the binary system. The apparent movement of the tail is a projection effect due to the relative alignment between the Sun, Earth, and 2006 VW139/288P changing between observations. The tail orientation is also affected by a change in the particle size. Initially, the tail was pointing towards the direction where comparatively large (about 1 millimeter in size) dust particles were emitted in late July. However, from Sept. 20 on, the tail began to point in the opposite direction from the Sun as the pressure of sunlight affects smaller (10 microns in size) dust particles where they are blown away from the nucleus by radiation pressure.

NASA, ESA, and J. DePasquale and Z. Levay (STScI)

Five, rectangular images stacked on top of each other. Each image holds two bright-white points surrounded by blue gas with a blue tail.

Asteroid 2006 VW139/288P probably broke into two pieces due to a fast rotation.

NASA, ESA, and J. Agarwal (Max Planck Institute for Solar System Research)

Asteroid Vesta and Dwarf Planet Ceres

Hubble captured images of the two most massive objects in the Asteroid Belt, Ceres and Vesta, to help NASA better plan the Dawn spacecraft's visit to these two worlds.

Left: mottled spheroid in colors of white, grey, and tan. Left: mottled spheroid mainly bluish-grey and white with a slight some tan areas.

Hubble made observations of Ceres and Vesta to help astronomers prepare for the NASA DAWN mission.

Vesta image: NASA; ESA; L. McFadden and J.Y. Li (University of Maryland, College Park); M. Mutchler and Z. Levay (Space Telescope Science Institute, Baltimore); P. Thomas (Cornell University); J. Parker and E.F. Young (Southwest Research Institute); and C.T. Russell and B. Schmidt (University of California, Los Angeles);
Ceres image: NASA; ESA; J. Parker (Southwest Research Institute); P. Thomas (Cornell University); L. McFadden (University of Maryland, College Park); and M. Mutchler and Z. Levay (Space Telescope Science Institute)

Hubble's observations of Ceres revealed bright and dark regions on the asteroid's surface that could be topographic features, such as craters, and/or areas containing different surface material. Large impacts may have caused some of these features and potentially added new material to the landscape.

Hubble images of Vesta allowed researchers to map its southern hemisphere, a region dominated by a giant impact basin formed billions of years ago. Hubble discovered the basin and its central peak through observations made in 1997. NASA's Dawn Mission later confirmed that the basin is actually two colossal impact craters—the 310 mile (500 km) wide Rheasilvia basin, and the older 250 mi (400 km) wide Veneneia crater. Rheasilvia’s width is 95% of the mean diameter of Vesta and about 12 miles deep. Its central peak, which Hubble first detected in its 1997 observations, rises 12-16 miles and is more than 100 miles wide. If Earth had a crater of proportional size, it would fill the Pacific Ocean basin.

The impact broke off chunks of Vesta, propelling about one-percent of the asteroid into space. This produced more than 50 smaller asteroids that astronomers have nicknamed "vestoids," along with many more smaller fragments in the asteroid belt and ejected into the solar system. Roughly 6 percent of all meteorites we find on Earth are likely the result of this ancient impact in deep space.

Hubble's sharp "eye" saw features as small as about 37 miles (60 kilometers) across on Vesta. The image above shows the difference in brightness and color on the asteroid's surface.

Hubble's view also revealed global features stretching from the northern to the southern hemisphere. The image above shows widespread differences in brightness in the east and west, which probably reflects a difference in composition. The size of these different regions varies. Some are hundreds of miles across.

Hubble Reveals Huge Crater on the Surface of the Asteroid Vesta

Left: This Hubble image of the asteroid Vesta was taken in May 1996 when the asteroid was 110 million miles from Earth. The asymmetry of the asteroid and "nub" and the south pole is suggested a large impact event that NASA's Dawn spacecraft later confirmed. The image was digitally restored to yield an effective scale of six miles per pixel (picture element). Center: A color-encoded elevation map of Vesta clearly shows the giant 285- mile diameter impact basin and "bull's-eye" central peak. The map was constructed from 78 Wide Field Planetary Camera 2 pictures. Surface topography was estimated by noting irregularities along the limb and at the terminator (day/night boundary) where shadows are enhanced by the low Sun angle. Right: A 3-D computer model of Vesta synthesized from Hubble topographic data. The crater's central peak is clearly visible near the pole. The surface texture on the model is artificial, and is not representative of the true brightness variations on the asteroid. Elevation features have not been exaggerated.

NASA, ESA, Ben Zellner (Georgia Southern University), and Peter Thomas (Cornell University)

Learn More

Comet or Asteroid? Hubble Discovers that a Unique Object is a Binary
Hubble helped an international team of astronomers find that an unusual object in the asteroid belt is actually two asteroids orbiting each other that have comet-like features.
Suspected Asteroid Collision Leaves Odd X-Pattern of Trailing Debris
Hubble imaged a mysterious X-shaped debris pattern and trailing streamers of dust that suggest a head-on collision between two asteroids.
Hubble Sees Asteroid Spout Six Comet-like Tails
Astronomers using Hubble identified what they can only describe as a never-before-seen "weird and freakish object" in the asteroid belt that looks like a rotating lawn sprinkler.
Hubble Witnesses an Asteroid Mysteriously Disintegrating
Hubble photographed the never-before-seen breakup of an asteroid into as many as 10 smaller pieces.
Hubble Images of Asteroids Help Prepare
for Spacecraft Visit
Hubble images of Vesta and Ceres, two of the most massive asteroids in the asteroid belt, help astronomers plan for NASA's Dawn spacecraft's tour.
Hubble Reveals Huge Crater on the Surface of the Asteroid Vesta
Astronomers have used Hubble to discover a giant impact crater on the asteroid Vesta. The crater is a link in a chain of events thought responsible for forming a distinctive class of tiny asteroids as well as some meteorites that reached Earth.