Funnily enough I thought I was having a bad day on Sunday. Turns out, I was actually rather lucky!
Blink and you missed it: Asteroid came within 90,000 km, only one sky-watcher saw it
A small asteroid made a rare, close pass between Earth and the moon on August 28. 2016 QA2 is estimated by the Minor Planet Center (MPC) as being somewhere between 25 and 55 metres in diameter – so small that it nearly passed without notice. The MPC's note about the asteroid attributes its discovery to Brazil's SONEAR …
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Wednesday 31st August 2016 08:08 GMT Pascal Monett
Or the change imposed by a close fly-by of Earth could send it careening too close to the Sun and get it ejected from the solar system entirely.
Don't know, not an astronomer, but theoretically it should be possible.
The much more likely outcome is that it will just smack into our home planet someday. Maybe over the ocean, so as not to harm anyone, but within sight of some camera or satellite, so we can get high-resolution footing out of the explosion. That might focus some minds on the issue before it is too late.
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Wednesday 31st August 2016 08:28 GMT Version 1.0
At its closest pass, whatever distance it is, would its orbit around the sun be affected by earth's gravity and maybe make it come closer next time?
It's possible, but just as likely that it would move further away. You can calculate it but there are still many unknowns so the results are not certain either way.
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Wednesday 31st August 2016 12:06 GMT Michael H.F. Wilkinson
Re: Facebook announcement?
I trust they informed the IAU's CBAT or MPC NEO pages as well. That is the standard procedure.
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Wednesday 31st August 2016 18:19 GMT VinceH
Re: Distance fropm the sun
Having only just read this article, clearly the numbers have been corrected - but it's interesting to see that they've gone from "between around 185,000 km and 285,000 km from the Sun" to "between around 115,000,000 km and 177,000,000 km from the Sun" - so the mistake wasn't a simple rounding error. (And the new figures make sense with Earth's semi-major axis.)
So I wonder what caused that mistake - and I wonder if it's in some way related to the disagreement about its future near miss with us:
"This pass was harmless, but if SONEAR's current characterisation of 2016 QA2's orbit is correct (more observations will be made, we're certain), it will come very close one day: “the minimum distance between the orbital 2016 QA2 and the earth is only 60 miles away” – or a bit over 95 km.
SONEAR doesn't mention when that's likely take place; a much more reassuring number comes from NASA's Jet Propulsion Laboratory, which gives the minimum orbit intersection distance (MOID) as 0.00037 astronomical units – or 55,000 km."
60 miles versus 55,000 km - something rounded to the nearest 1,000 coupled with an accidental unit change perhaps? Checking ther SONEAR observatory Facebook post, that actually says 60,000km.
Ah, or perhaps a mistranslation - the Portuguese part says "A distância minima orbital entre o 2016 QA2 e a Terra é de apenas 60 mil km" - did someone perhaps mistranslate 60 mil (meaning sixty thousand) as 60 miles?
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Wednesday 31st August 2016 18:48 GMT Bill Gray
A few corrections/extensions :
@wolfetone : "It's funny how only one star gazer saw that asteroid..."
Quite a few did. After SONEAR saw it, two observatories in Australia confirmed the discovery. Then several observatories in Europe (including one in the UK) caught it as it came closer to perigee. It's a bit of a long story for a forum post; details are at
http://www.projectpluto.com/s510921.htm
Suffice to say that MPC rarely announces objects based on observations from a single observatory.
@frank ly : yes, the orbit was _very_ much affected by the flyby. Before then, it had an orbital period of about 350 days, and went from 0.7636 AU at perihelion to 1.18045 AU at apohelion or aphelion or whatever you want to call it (opinions vary). Multiply those distances by about 149.598 million to get kilometers, and by something else to get gigalinguine or whatever the official
El Reg units are.
After the flyby, it'll take about 336 days to get around the sun, and those distances will be 0.7168 AU and 1.17482 AU. So the summers will be a little hotter, and the winters about the same.
@brotherelf : "It's the kind of distance where I start to wonder if that's center-to-center or surface-to-surface..." Minimum distance from the earth's center was 86573 +/- 2 km, or about thirteen earth radii.
More technical details are at
http://www.projectpluto.com/neocp2/mpecs/S510921.htm