Capturing the moment the asteroid Eurybates eclipsed a star

Today’s Video of the Day from NASA Goddard describes the moment that the asteroid Eurybates passed in front of a star on October 20, 2021. Just outside of Las Vegas recently, dozens of astronomers pointed their telescopes at the sky to watch for the light of the star to blink out. 

According to NASA, the event was so miniscule it would have been easy to miss, but the data gathered in those few seconds will contribute to the success of NASA’s Lucy mission, which launched from Cape Canaveral Space Force Station in Florida on October 16.

Eurybates is one of the asteroids Lucy will visit over the next 12 years. Lucy’s target destinations, known as “Trojan” asteroids, are clustered in two swarms that orbit the Sun at about the same distance as Jupiter.

When Eurybates eclipsed a star, an “occultation” was expected to cast a 40-mile-wide shadow the size of the asteroid across Nevada. An occultation is an event where one celestial object passes in front of another, blocking the object from view.

The astronomers spread out inside the shadow’s predicted path. The goal was to measure the width of Eurybates down to several hundred feet, or a couple hundred meters, and to determine its shape. 

The data will be used by Lucy researchers and combined with information gathered by the Lucy spacecraft’s close flyby of Eurybates in 2027.

“It really does look like a star just vanished,” said Marc Buie, occultation science lead for the Lucy mission at the Southwest Research Institute. “It’s kind of a weird thing to see, but an occultation gives us really valuable information.”

“Occultations are one way for us to learn as much as we can about the objects before Lucy gets there, so that we can make the most of the brief opportunity we’ll get when the spacecraft is super close to each target,” said Brian Keeney, an occultation specialist for the Lucy mission.

“Lucy will see each asteroid’s surface, but we need to learn more about the interior, which is where occultations can help.”

Video Credit: NASA Goddard 

–—

By Chrissy Sexton, Earth.com Staff Writer