from the Think-we'd-notice-if-it-didn't-miss? dept.
A large asteroid, 3122 Florence, has passed by Earth at a distance of around 7 million kilometers (about 0.047237 AU):
Asteroid Florence, a large near-Earth asteroid, will pass safely by Earth on Sept. 1, 2017, at a distance of about 4.4 million miles, (7.0 million kilometers, or about 18 Earth-Moon distances). Florence is among the largest near-Earth asteroids that are several miles in size; measurements from NASA's Spitzer Space Telescope and NEOWISE mission indicate it's about 2.7 miles (4.4 kilometers) in size.
"While many known asteroids have passed by closer to Earth than Florence will on September 1, all of those were estimated to be smaller," said Paul Chodas, manager of NASA's Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California. "Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began."
This relatively close encounter provides an opportunity for scientists to study this asteroid up close. Florence is expected to be an excellent target for ground-based radar observations. Radar imaging is planned at NASA's Goldstone Solar System Radar in California and at the National Science Foundation's Arecibo Observatory in Puerto Rico. The resulting radar images will show the real size of Florence and also could reveal surface details as small as about 30 feet (10 meters).
All that money just whizzing by.
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2012 TC4 has passed by Earth:
2012 TC4 is estimated to be 45 to 100 feet (15 to 30 meters) in size. Orbit prediction experts say the asteroid poses no risk of impact with Earth. Nonetheless, its close approach to Earth is an opportunity to test the ability of a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.
This asteroid was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) on Hawaii back in 2012. Pan-STARRS conducts a near-Earth object (NEO) survey funded by NASA's NEO Observations Program, a key element of NASA's Planetary Defense Coordination Office. However, 2012 TC4 traveled out of the range of asteroid-tracking telescopes shortly after it was discovered.
Based on the observations they were able to make in 2012, asteroid trackers predicted that it should come back into view in the fall of 2017. Observers with the European Space Agency and the European Southern Observatory were the first to recapture 2012 TC4, in late July 2017, using one of their large 8-meter aperture telescopes. Since then, observers around the world have been tracking the object as it approaches Earth and reporting their observations to the Minor Planet Center.
This "test" of what has become a global asteroid-impact early-warning system is a volunteer project, conceived and organized by NASA-funded asteroid observers and supported by the NASA Planetary Defense Coordination Office (PDCO). As explained by Michael Kelley, program scientist and NASA PDCO lead for the TC4 observation campaign, "Asteroid trackers are using this flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid-impact threat."
Previously: NASA Formalizes Planetary Defense Coordination Office to Track Asteroids
NASA and FEMA Conduct Asteroid Threat Response Exercise
Surprise Flyby of Asteroid on January 9, 2017
NASA to Redirect an Asteroid's Moon With Kinetic Impact
Asteroid 2012 TC4 Will Pass Close to Earth on October 12th
4.4 Kilometer Asteroid Safely Passes by Earth (two moons discovered)
(Score: 3, Informative) by stormwyrm on Saturday September 02 2017, @05:20AM (2 children)
I know it isn't hitting the earth any time soon, but here's a little what if. According to Wikipedia, it has a rotation period around the sun of 859 days. The length of its orbit would be 4(1.7684 AU)E(0.4230) = 4(2.6455×108 km)1.498 = 1.585×109 km, so its orbital velocity would be 21.36 km/s. Earth's orbital velocity is 29.78 km/s, so impact would be at least 8.42 km/s, and up to 51.14 km/s, depending on the relative motion of the orbits at time of impact. Assuming Florence to be dense rock (since there are no mass estimates yet from a cursory look) and assuming an impact velocity somewhere in the middle of that range (21.7 km/s, not unusual for asteroids), impact would be like this [ic.ac.uk]. It looks at the very least capable of massive regional devastation, and would likely be sufficient to trigger a minor mass extinction event. Might be big enough to trigger climate change on the level of the Younger Dryas [wikipedia.org]. Not quite a planet killer like the one that killed the dinosaurs, but an impact like it probably would spell the end of human civilisation as we know it.
Numquam ponenda est pluralitas sine necessitate.
(Score: 0) by Anonymous Coward on Saturday September 02 2017, @08:59AM (1 child)
It's just one of those things where I don't trust the rest of your numbers. I guess you cite wikipedia without linking to it at least but still...
I guess we should all be double checking each other anyway.
(Score: 1, Informative) by Anonymous Coward on Saturday September 02 2017, @09:46AM
(Score: -1, Redundant) by Anonymous Coward on Saturday September 02 2017, @09:38AM
Not a real planet. A real planet would have cleared its orbit.
(Score: 2) by Thexalon on Saturday September 02 2017, @03:44PM (4 children)
A swing and a miss. Strike 1!
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 0) by Anonymous Coward on Saturday September 02 2017, @04:29PM (3 children)
Missing us by 18 earth-moon distances. That sounds like a "ball" to me. Inside the lunar orbit might be the strike zone??
(Score: 2) by Thexalon on Saturday September 02 2017, @09:25PM (2 children)
It would be a ball, except they swung at the pitch.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 1, Funny) by Anonymous Coward on Saturday September 02 2017, @09:43PM (1 child)
> "they" (no antecedent)
Who's on first? ...
(Score: 2) by Thexalon on Saturday September 02 2017, @10:27PM
Yes, he is. And What is on second, I Don't Know is on third, and Naturally is the pitcher.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 3, Interesting) by Anonymous Coward on Saturday September 02 2017, @07:23PM
https://cneos.jpl.nasa.gov/news/news199.html [nasa.gov]
> Radar images of asteroid 3122 Florence obtained at the 70-meter antenna at NASA’s Goldstone Deep Space Communications Complex between August 29 and September 1 have revealed that the asteroid has two small moons, and also confirmed that main asteroid Florence is about 4.5 km (2.8 miles) in size. Florence is only the third triple asteroid known in the near-Earth population out of more than 16,400 that have been discovered to date. All three near-Earth asteroid triples have been discovered with radar observations and Florence is the first seen since two moons were discovered around asteroid 1994 CC in June 2009.
>
> The sizes of the two moons are not yet well known, but they are probably between 100 - 300 meters (300-1000 feet) across. The times required for each moon to revolve around Florence are also not yet known precisely but appear to be roughly 8 hours for the inner moon and 22 to 27 hours for the outer moon. The inner moon of the Florence system has the shortest orbital period of any of the moons of the 60 near-Earth asteroids known to have moons. In the Goldstone radar images, which have a resolution of 75 meters, the moons are only a few pixels in extent and do not reveal any detail.
Think about this -- at 18 lunar distances, they bounced radar off two 100-300 meter rocks and plucked the echos out of the background noise.