As Eurybates eclipsed the star, a phenomenon researchers call an “occultation,” a 40-mile- (64-kilometer-) large shadow the size of the asteroid passed over the area. By spreading out inside the shadows forecasted course across Nevada, astronomers sought to determine the width of Eurybates to a number of hundred feet, or a number of hundred meters, and to ascertain its shape. This details will be used by Lucy scientists to supplement information collected by the Lucy spacecrafts close flyby of Eurybates in 2027, which is designed to identify what the asteroid is made of and where in the planetary system it formed billions of years ago.
Why Occultations?
An occultation is any occasion where one celestial item passes in front of another, blocking the latter object from an observers view. The best-known example is a solar eclipse, which takes place when the Moon passes between the Sun and Earth, blocking the Sun from our view.
” It truly does appear like a star simply disappeared,” stated Marc Buie, occultation science lead for the Lucy objective at the Southwest Research Institute, which is headquartered in San Antonio. Buie helped collaborate the Eurybates observations in Nevada. “Its type of an odd thing to see, but an occultation gives us truly important information.”
Observing occultations is one of the tools researchers have for gathering exact information about the size and shape of Lucys target locations, called “Trojan” asteroids. These Trojans are clustered in 2 swarms that orbit the Sun at about the very same distance as Jupiter (though theyre as far from Jupiter as they are from the Sun). Trojan asteroids are residues of the early solar system, with the biggest ones named after characters from Greek mythology. The Lucy objective, for the first time, will examine seven of them up close, assisting scientists sharpen the theory of how the worlds formed and ended up in their current places.
Lucy is headed to Jupiters Trojan asteroids! Watch this video to see the 12-year path our Lucy spacecraft is taking over its mission to fly by the Trojan asteroids and uncover the tricks of planetary development.
While scientists can find Trojan asteroids using powerful observatories such as NASAs Hubble Space Telescope (and in truth discovered a moon of Eurybates this way in 2018), the asteroids appear just as little points of light, so its challenging to exactly identify their real shapes and sizes.
” Occultations are one method for us to learn as much as we can about the items before Lucy arrives, so that we can take advantage of the short chance well get when the spacecraft is extremely near each target,” said Brian Keeney, an occultation specialist for the Lucy objective at the Southwest Research Institute.
After Lucy reaches each asteroid, scientists will be able to determine each asteroids mass. Researchers hope to compare the compositions of the Trojan asteroids to figure out if they came from the various or exact same parts of the solar system about 4.5 billion years back, and how the Trojans relate to other asteroids in the solar system.
” Lucy will see each asteroids surface, however we require for more information about the interior, which is where occultations can help,” Keeney stated.
Viewing a Star Disappear
To prepare for an occultation, astronomers predict a shadows course throughout Earth, based on the known orbit of the asteroid and the exact position of the star to be occulted. Then they established dozens of telescopes along a line perpendicular to that path and wait on the asteroid to eclipse a specific star. They count the seconds that starlight blinks out as the asteroid passes in front of it and then utilize the asteroids known velocity to determine its width.
Given that the occultation time, and thus width, is different at each point on the line where telescopes are stationed– with each telescope station corresponding to a various line throughout the asteroid– researchers can also identify the shape of an asteroids shape by integrating data from each telescope. By observing numerous occultations of the exact same asteroid, researchers can capture different sides of the asteroid and combine their two-dimensional shape forecasts into a three-dimensional shape model.
Observing occultations from Earth is one of the tools researchers have for collecting precise info about the shapes and size of Lucys target locations, known as “Trojan” asteroids. Credit: NASA Goddard/James Tralie
” Occultations have shown to be an exceptional strategy to take full advantage of the science return of objectives such as Lucy,” stated Adriana Ocampo, program executive for the Lucy objective based at NASA Headquarters in Washington.
Accurate forecasts of future occultation times and places rely on impressive info related to star and asteroid areas. To capture an occultation of a 10-mile- (20-kilometer-) wide asteroid, for instance, Buie would have spread out telescopes out along a 190-mile (300-kilometer) course.
Astronomers predictions have actually enhanced significantly thanks to Hubble and ESAs (the European Space Agency) Gaia satellite, which assist determine the accurate places of nearly 2 billion stars. Additionally, the trajectories of Lucys fast-moving target asteroids are constantly monitored and improved utilizing ground-based telescopes and sometimes Hubble.
How to Catch an Occultation
Buie calls occultation occasions “mega projects,” as they require big groups, accurate area forecasts for each telescope, and numerous telescopes for effective information collection. In Nevada, for circumstances, amateur and professional astronomers from throughout the nation, consisting of instructors and high school trainees, utilized 37 telescopes to observe Eurybates.
Occultations occur all over world, from Argentina to South Africa, Senegal and Spain. Buie and other Lucy scientists must collaborate travel to these locations, find observation volunteers locally, and train them.
” Occultations offer an essential international collaborative factor of clinical improvement for the good of humankind, excitement, engagement and inspiration which is at the core of NASAs mission,” stated Ocampo, who takes part in observation projects.
On top of the logistical challenges of organizing occultation campaigns, researchers should contend with unforeseeable weather condition. Effective campaigns depend upon clear skies. As observers waited on Eurybates occultation in Nevada, they saw clouds approaching them.
” If that Eurybates occultation had actually been an hour later on, nobody wouldve seen anything,” Buie stated. “The clouds would have wiped us out.”
The team will continue to observe occultations till Lucys last flyby of Trojan asteroid Patroclus in 2033, even in the face of bad weather condition.
To discover how Lucys complex and distinct trajectory was developed and the big planetary system questions the objective will assist answer, take a look at: NASAs Lucy Mission: A Journey to the Young Solar System.
By Allison Gasparini, with Lonnie Shekhtman.
Illustration of the Lucy spacecraft near a large asteroid with Jupiter visible in the distant background. Credit: Southwest Research Institute
Gathering near Las Vegas recently, dozens of astronomers spread out throughout the area, pointed their telescopes at the sky, and awaited the minute on October 20 that the light from a distant star blinked out.
It was an event so tiny it would have been easy to miss. The information collected in those few seconds will contribute to the success of NASAs Lucy objective, which launched from Cape Canaveral Space Force Station in Florida on October 16.
Due to the fact that the asteroid Eurybates had actually passed in front of it, the star appeared to briefly blink out. Eurybates is one of a handful of asteroids Lucy will go to over the next 12 years.
As Eurybates eclipsed the star, a phenomenon scientists call an “occultation,” a 40-mile- (64-kilometer-) broad shadow the size of the asteroid passed over the region. Observing occultations is one of the tools researchers have for collecting accurate info about the size and shape of Lucys target destinations, understood as “Trojan” asteroids. After Lucy reaches each asteroid, scientists will be able to determine each asteroids mass. Scientists hope to compare the compositions of the Trojan asteroids to figure out if they came from the same or various parts of the solar system about 4.5 billion years ago, and how the Trojans relate to other asteroids in the solar system.
They count the seconds that starlight blinks out as the asteroid passes in front of it and then utilize the asteroids recognized velocity to compute its width.
