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Blurry new photos of a mountain - size of it , " satellite sea wolf " asteroid thatrecently made its close approach to Earth in more than a centuryhave expose a surprising new lineament of the mammoth space rock — it has a secret minimoon .
Asteroid 2011 UL21 is apotentially hazardous , near - Earth object that was antecedently calculate to be somewhere between 1.1 and 2.4 miles ( 1.7 to 3.9 km ) widely , constitute it prominent than 99 % of near - world asteroid . At this size , it could likely pass over out an intact continent and make devastating climate modification on a global ordered series , take in it theplanet killermoniker . However , it is not predicted to strike Earth in the future .
A spacecraft photo of a binary asteroid. Astronomers recently spotted a minimoon circling a massive asteroid as it flew past Earth.
On June 27 , 2011 UL21 reach its closest peak to Earth in at least 110 years when it zipped past our planet at more than 58,000 mph ( 93,000 km / h ) . The elephantine quad rock reached a minimum distance of around 4.1 million Swedish mile ( 6.6 million kilometer ) — around 17 times further from our planet thanthe moon . This likely makes it one of the 10 largest asteroids to give this close to Earth since 1900 , harmonize to astrophysicist Gianluca Masi of theVirtual Telescope Projectin Italy .
scientist atNASA ’s Goldstone Deep Space Communications Complex in California monitor the historic flyby using the GoldstoneSolar SystemRadar telescope . The squad snapped farinaceous " bistatic " images of the mammoth rock by bouncing radio receiver waves off its aerofoil , which expose two thing : First , the space John Rock is probably only around 1 land mile ( 1.6 km ) astray ; and secondly , there was a second , smaller asteroid orb it .
Two days later , on June 29 , the same scope also captured look-alike of the pyramid - size asteroid 2024 MK as itpassed by our satellite nigher than the moon . These pictures revealed that this recently get word space rock wasknocked off course by the near encounter .
These bistatic images show 2011 UL21 (top) and its unnamed minimoon (bottom) at five different points during its recent flyby.
Thenew imagesof both asteroid were released July 3 by NASA ' Jet Propulsion Laboratory ( JPL ) .
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2011 UL21 ’s fresh discovered minimoon , which has not been refer , is what investigator call a pocket-sized - body planet — an asteroid thatorbits another larger asteroidor dwarf planet . From the images it is unclear how large the raw space rock really is but it is likely significantly smaller than 2011 UL21 .
The two asteroid form what is known as a binary organization , and are split up by a distance of around 1.9 miles ( 3 kilometer ) , according to JPL .
little - body planet are themost common types of natural satellite in the solar organization , and are especially common around asteroid this great .
" It is thought that about two - third of asteroid of this size are binary systems , and their breakthrough is in particular important because we can use measurement of their relative post to estimate their mutual orbits , masses , and denseness , which provide central information about how they may have formed,“Lance Benner , a JPL scientist who led the recent watching , say in a statement .
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It ’s also potential that the newly disclose moonlet is actually two separate small - trunk satellites in near proximity , as NASA ’s Lucy mission recently provedis the case with asteroid Dinkinesh .
The next time we will get a good look at 2011 UL21 and its newfound companion will be in 2089 , when the space careen will get to within 1.7 million Roman mile ( 2.7 million klick ) of our major planet — about two and a one-half sentence close to us than its current approach .
