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Thursday, August 29, 2019
For first time, astronomers catch asteroid in the act of changing color
Last December, scientists discovered an “active” asteroid within the asteroid belt, sandwiched between the orbits of Mars and Jupiter. The space rock, designated by astronomers as 6478 Gault, appeared to be leaving two trails of dust in its wake — active behavior that is associated with comets but rarely seen in asteroids.
While astronomers are still puzzling over the cause of Gault’s comet-like activity, an MIT-led team now reports that it has caught the asteroid in the act of changing color, in the near-infrared spectrum, from red to blue. It is the first time scientists have observed a color-shifting asteroid, in real-time.
“That was a very big surprise,” says Michael Marsset, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “We think we have witnessed the asteroid losing its reddish dust to space, and we are seeing the asteroid’s underlying, fresh blue layers.”
Marsset and his colleagues have also confirmed that the asteroid is rocky — proof that the asteroid’s tail, though seemingly comet-like, is caused by an entirely different mechanism, as comets are not rocky but more like loose snowballs of ice and dust.
“It’s the first time to my knowledge that we see a rocky body emitting dust, a little bit like a comet,” Marsset says. “It means that probably some mechanism responsible for dust emission is different from comets, and different from most other active main-belt asteroids.”
Marsset and his colleagues, including EAPS Research Scientist Francesca DeMeo and Professor Richard Binzel, have published their results today in the journal Astrophysical Journal Letters.
A rock with tails
Astronomers first discovered 6478 Gault in 1988 and named the asteroid after planetary geologist Donald Gault. Until recently, the space rock was seen as relatively average, measuring about 2.5 miles wide and orbiting along with millions of other bits of rock and dust within the inner region of the asteroid belt, 214 million miles from the sun.
In January, images from various observatories, including NASA’s Hubble Space Telescope, captured two narrow, comet-like tails trailing the asteroid. Astronomers estimate that the longer tail stretches half a million miles out, while the shorter tail is about a quarter as long. The tails, they concluded, must consist of tens of millions of kilograms of dust, actively ejected by the asteroid, into space. But how? The question reignited interest in Gault, and studies since then have unearthed past instances of similar activity by the asteroid.
“We know of about a million bodies between Mars and Jupiter, and maybe about 20 that are active in the asteroid belt,” Marsset says. “So this is very rare.”
He and his colleagues joined the search for answers to Gault’s activity in March, when they secured observation time at NASA’s Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Over two nights, they observed the asteroid and used a high-precision spectrograph to divide the asteroid’s incoming light into various frequencies, or colors, the relative intensities of which can give scientists an idea of an object’s composition.
From their analysis, the team determined that the asteroid’s surface is composed mainly of silicate, a dry, rocky material, similar to most other asteroids, and, more importantly, not at all like most comets.
Comets typically come from the far colder edges of the solar system. When they approach the sun, any surface ice instantly sublimates, or vaporizes into gas, creating the comet’s characteristic tail. Since Marsset’s team has found 6478 Gault is a dry, rocky body, this means it likely is generating dust tails by some other active mechanism.
A fresh change
As the team observed the asteroid, they discovered, to their surprise, that the rock was changing color in the near-infrared, from red to blue.
“We've never seen such a dramatic change like this over such a short period of time,” says co-author DeMeo.
The scientists say they are likely seeing the asteroid’s surface dust, turned red over millions of years of exposure to the sun, being ejected into space, revealing a fresh, less irradiated surface beneath, that appears blue at near-infrared wavelengths.
“Interestingly, you only need a very thin layer to be removed to see a change in the spectrum,” DeMeo says. “It could be as thin as a single layer of grains just microns deep.”
So what could be causing the asteroid to turn color? The team and other groups studying 6478 Gault believe the reason for the color shift, and the asteroid’s comet-like activity, is likely due to the same mechanism: a fast spin. The asteroid may be spinning fast enough to whip off layers of dust from its surface, through sheer centrifugal force. The researchers estimate it would need to have about a two-hour rotation period, spinning around every couple of hours, versus Earth’s 24-hour period.
“About 10 percent of asteroids spin very fast, meaning with a two- to three-hour rotation period, and it’s most likely due to the sun spinning them up,” says Marsset.
This spinning phenomenon is known as the YORP effect (or, the Yarkovsky-O’Keefe-Radzievskii-Paddack effect, named after the scientists who discovered it), which refers to the effect of solar radiation, or photons, on small, nearby bodies such as asteroids. While asteroids reflect most of this radiation back into space, a fraction of these photons is absorbed, then reemitted as heat, and also momentum. This creates a small force that, over millions of years, can cause the asteroid to spin faster.
Astronomers have observed the YORP effect on a handful of asteroids in the past. To confirm a similar effect is acting on 6478 Gault, researchers will have to detect its spin through light curves — measurements of the asteroid’s brightness over time. The challenge will be to see through the asteroid’s considerable dust tail, which can obscure key portions of the asteroid’s light.
Marsset’s team, along with other groups, plan to study the asteroid for further clues to activity, when it next becomes visible in the sky.
“I think [the group’s study] reinforces the fact that the asteroid belt is a really dynamic place,” DeMeo says. “While the asteroid fields you see in the movies, all crashing into each other, is an exaggeration, there is definitely a lot happening out there every moment.”
This research was funded, in part, by the NASA Planetary Astronomy Program.
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Garcelle Beauvais joining cast of ‘Real Housewives of Beverly Hills’
Garcelle Beauvais is taking her talents to the small screen and joining Bravo’s Real Housewives of Beverly Hills.
The actress will be the first Black woman to be a part of RHOBH and it’s about time considering the show is gearing up for its tenth season. The network confirmed the news on Thursday and announced the addition of another new cast member, Sutton Stracke.
“I am excited and proud to be joining the cast of such a wildly popular and beloved show like The Real Housewives of Beverly Hills. As a working actor who has been in the industry for some time, it’s exhilarating to have the opportunity to delve into a new chapter in the entertainment spectrum. As the first African American Housewife in the Beverly Hills franchise, I am honored and humbled by this awesome opportunity to exemplify the fact that Black Girl Magic lives and thrives in every zip code!” Garcelle said in a statement to The Daily Dish.
“Already being intimately familiar with the spotlight of Hollywood, my journey of successes and trials has already been chronicled and shared with my many loyal supporters around the world. The continual encouragement, support and yes, even at times, criticism, have helped make me the dynamic woman I am today. I’m excited to share the many ongoing daily surprises, laughs and joys of being a working mother in today’s crazy world. The hustle is R-E-A-L! No games, all heart and a little dash of fashion-filled sass is what you’ll get when you step into my sphere…and I wouldn’t have it any other way!”
Garcelle Beauvais is booked and busy, and she will also appear in the star-studded sequel, Coming 2 America.
The post Garcelle Beauvais joining cast of ‘Real Housewives of Beverly Hills’ appeared first on theGrio.
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Is Sasha Obama gearing up to attend the University of Michigan next week?
Sasha Obama is not doing the legacy thing by attending the alma maters of her famous parents as she takes the next steps in her education.
—PHOTOS: Check out all the famous faces cast in ‘Coming To America 2’—
The youngest Obama daughter chose the University of Michigan to attend college starting next Tuesday, according to The Detroit News.
Both Michelle and Barack Obama are Harvard law graduates and their oldest daughter Malia currently there as an undergrad student at the Ivy League institution. As an undergrad, her father attended Columbia University and mom went to Princeton University.
Sasha was reportedly spotted on campus surrounded by a security detail as she attended freshmen orientation like the rest of her peers.
The University of course refused to give out any info on if Sasha is a student or not.
Let’s just hope Sasha keeps some good friends around her who don’t try to sneak pics of her for the gram.
Her sister Malia’s been bombarded with people catching her out living life and enjoying herself while imposing on her privacy while at college.
Last year Malia was snapped sitting together and chatting in Soho with Rory Farquharson who was rumored to be her boyfriend.
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Earlier this year, Sasha attended her high school prom, ahead of her graduation from the Sidwell Friends High School in June. Photos show the fresh-faced teen standing arm-in-arm with her date, Chris Milton, who wore a traditional black tuxedo.
The post Is Sasha Obama gearing up to attend the University of Michigan next week? appeared first on theGrio.
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Paul Mooney cancels comedy shows after explosive sex allegations with Richard Pryor’s son revealed
Paul Mooney is stepping away from the limelight for a bit after explosive rumors that he had a sexual encounter with Richard Pryor’s son went viral.
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Although the comedy legend has denied Richard Pryor’s former bodyguard’s claims that he had sex with a young Pryor Jr. way back when, and that Pryor put a $1 million hit out on him, Mooney cancelled his Atlanta Comedy Theater appearance Wednesday and Thursday, August 29 due to “health reasons.”
According to TMZ, a sign on door of the comedy venue reads: “ATTENTION!! Paul Mooney is NOT on show tonight due to health reasons. We will transfer purchase to Faizon Love or Donnell Rawlings. Let box office know.”
According to the outlet, Mooney’s pulled out of several appearances following the heat he’s gotten over the alleged sexual relationship with Richard Pryor Jr made by Rashon Kahn, Pryor Sr former bodyguard.
As previously reported, Mooney’s publicist, Cassandra Williams spoke about the statement saying, “There is no validity to Rashon Kahn’s statement as it relates to Mr. Paul Mooney,” according to TMZ.
—Catholic church paid Black abuse victims $235K LESS than white victims—
The development comes after an interview of Kahn, went viral on YouTube after it was posted by Comedy Hype on Monday, where he details the reason why the relationship between Pryor and Mooney ended.
Kahn, who has an upcoming book titled Everything Wasn’t Funny, states in the video that the two comedians “relationship became fragile because Paul Mooney had f****d Richard’s son by that time. He violated … Paul took advantage of the situation.”
The post Paul Mooney cancels comedy shows after explosive sex allegations with Richard Pryor’s son revealed appeared first on theGrio.
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