Scientists Observe Potentially Hazardous Asteroid Buzz Past Earth With Its Own Moon (space.com) 24
Meghan Bartels writes via Space.com: One of Earth's premier instruments for studying nearby asteroids is back to work after being rattled by earthquakes, and its first new observations show that a newly discovered space rock is actually two separate asteroids. The instrument is the planetary radar system at the Arecibo Observatory in Puerto Rico. The observatory was closed for most of January, after a series of earthquakes hit the island beginning on Dec. 28, 2019. The observatory reopened on Jan. 29. Meanwhile, on Jan. 27, scientists using a telescope on Mauna Loa in Hawaii spotted an asteroid that astronomers hadn't seen before. The team dubbed the newfound space rock 2020 BX12 based on a formula recognizing its discovery date.
Because of the size of 2020 BX12 and the way its orbit approaches that of Earth, it is designated a potentially hazardous asteroid. However, the space rock has already come as close to Earth as it will during this pass (2.7 million miles or 4.3 million kilometers); astronomers have calculated the asteroid's close approaches with Earth for the next century, and all will be at a greater distance than this one was. [...] Based on the observations, the scientists discovered that 2020 BX12 is a binary asteroid, with a smaller rock orbiting the larger rock. About 15% of larger asteroids turn out, on closer inspection, to be binary, according to NASA. The larger rock is likely at least 540 feet (165 meters) across, and the smaller one is about 230 feet (70 m) wide, according to the observations gathered by Arecibo. When the instrument observed the two space rocks on Feb. 5, they appeared to be separated by about 1,200 feet (360 m).
Because of the size of 2020 BX12 and the way its orbit approaches that of Earth, it is designated a potentially hazardous asteroid. However, the space rock has already come as close to Earth as it will during this pass (2.7 million miles or 4.3 million kilometers); astronomers have calculated the asteroid's close approaches with Earth for the next century, and all will be at a greater distance than this one was. [...] Based on the observations, the scientists discovered that 2020 BX12 is a binary asteroid, with a smaller rock orbiting the larger rock. About 15% of larger asteroids turn out, on closer inspection, to be binary, according to NASA. The larger rock is likely at least 540 feet (165 meters) across, and the smaller one is about 230 feet (70 m) wide, according to the observations gathered by Arecibo. When the instrument observed the two space rocks on Feb. 5, they appeared to be separated by about 1,200 feet (360 m).
Color me Disappointed. (Score:5, Informative)
Most of the other coverage of this object was fear mongering like:
"NASA reports a "potentially hazardous" asteroid will come close to Earth on February 15, 2020"
Which would of course be very scary until you realized how far away it would actually be. (If you were smart enough to know how far 3 million miles actually is.)
In case you want really want to worry, here is the NASA NEO Earth Close Approaches site:
https://cneos.jpl.nasa.gov/ca/ [nasa.gov]
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https://cneos.jpl.nasa.gov/glo... [nasa.gov]
It's own moon? (Score:2)
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About 15% of larger asteroids turn out, on closer inspection, to be binary,
Since when does this classify as a moon?
Have you asked it what its preferred pronoun is? Perhaps it identifies as a non-binary moon. Maybe you are just astroid-lunaphobic.
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I had thought that if the barycenter was outside of the more massive object then they were binary and not object and moon.
Na- it *has* to be more complicated than that, because if that's the only metric, then Jupiter isn't a satellite of Sol, and some day, the Earth will no longer be a satellite of Earth (even though it completes basically the same orbit, just further out)
Aren't they all? (Score:2)
I mean 'potentially hazardous' when they are close enough to 'buzz by'?
Asteroid with its own moon? (Score:2)
That's no moon.
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Barycenter (Score:2)
Based on the observations, the scientists discovered that 2020 BX12 is a binary asteroid, with a smaller rock orbiting the larger rock.
No, it doesn't. They orbit a common barycenter.
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Come on, dude. All orbits use a barycenter as one of their foci, not an object. Whether or not that barycenter is inside or outside of the object has to do with mass and distance. This is to say, the closer the smaller object is to the larger, the closer the barycenter will get to the center of gravity of the larger.
Thus, the question is this:
If the smaller object were 50% closer to the larger, and thus the barycenter within the larger, would it then fit your
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That's the case for every orbiting pair of objects. We still generally say that the Moon orbits the Earth and the Earth orbits the Sun, and so forth. It's meaningless to claim the Moon doesn't orbit the Earth just because the Earth wobbles around the barycenter as well.
In some cases the barycenter can be outside the main object (e.g. Jupiter orbits the Sun but the barycenter is outside the Sun's surface) but it's almost certainly not the case here. If the objects were the same shape and density, the 70m obj
Not hazardous (Score:2)
When the distance is more than 10 times the distance between Earth and our Moon, it is not potentially hazardous.
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PHA is a classification for bodies with orbits that come close to Earth's and enough mass to cause major damage if they were to ever impact us. There are a few thousand known ones so far, with none known to be on an actual collision course. It's estimated that Earth gets hit by an object in this category roughly once every 10,000 years.
"Moon"... (Score:1)