It’s not the size or appearance that makes the Euphrosyne asteroids unique. It’s their unusual orbital path. This particular family of asteroids orbit our solar system well above the equator of the solar system, also called the ecliptic.
The primary asteroid is believed to be the leftovers of an enormous collision about 700 million years ago. Astronomers believe this collision was one of the last massive collisions in the solar system.
It’s about 156 miles across and is one of the ten largest asteroids in the main belt.
Ceres is the biggest asteroid in the asteroid belt between Mars and Jupiter.
The four largest asteroids in the main belt make up about half the mass of the entire asteroid belt.
Why the interest in the Euphrosyne asteroids? A new study led by scientists at NASA’s Jet Propulsion Laboratory (JPL) used the NEOWISE telescope to study these asteroids and learn more about the origins of Near Earth Objects (NEOs).
NEOs are bodies that approach the orbit of Earth as they make their way around the sun. According to a NASA press release, “this population is short-lived on astronomical timescales and is fed by other reservoirs of bodies in our solar system.”
The JPL researchers believe one of these “other reservoirs” may be Euphrosyne asteroids. Euphrosyne asteroids’ orbits slightly change over the course of millions of years with gravitational interactions with Saturn.
“The Euphrosynes have a gentle resonance with the orbit of Saturn that slowly moves these objects, eventually turning some of them into NEOs,” said Joseph Masiero, JPL’s lead scientist on the Euphrosynes study. “This particular gravitational resonance tends to push some of the larger fragments of the Euphrosyne family into near-Earth space.”
With more than 700,000 asteroidal bodies in the main belt that we know of, finding their points of origins can be tricky. But with Euphrosynes asteroids, it’s possible.
“But with objects coming from this family, in such a unique region, we are able to draw a likely path for some of the unusual, dark NEOs we find back to the collision in which they were born,” says Masiero.
The NEOWISE Telescope
The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope was perfectly suited for this study. NEOWISE spots objects through the infrared spectrum (heat). This makes finding dark objects much easier than telescopes that observe through the visual light spectrum.
NEOWISE wasn’t originally designed to look for objects coming close to Earth. In 2009, it launched as the Wide-field Infrared Survey Explorer (WISE). It was shut down in 2011 but would gain the “Near-Earth” part of its name when it was reactivated in 2013.
Here’s a picture of WISE before it launched in 2009.
And here are a few of the best images snapped by the spacecraft over the years.
More than 100 asteroids captured by NEOWISE. (look for the lines of red dots)