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Ross 54
2009-Feb-10, 04:13 PM
Newly discovered asteroid 2009 BD81 will come especially near Earth in 2044, says a Feb. 7 report on this website. The first orbital diagram in the article shows that the object was very near aphelion on June 3, 2007. Its orbital period is given, elsewhere, as either 1504 days (NASA) or 1643 days (Astronomical Research Institute, the organization associated with the discovery). Using the shorter orbit and doing the math seems to show that the object will again be at or near aphelion, out near Jupiter's orbit, throughout 2044. The longer orbit has it nearer the Sun, but still outside the orbit of Mars, at its nearest , in 2044. It doesn't appear that a close encounter with Earth can occur in 2044. Have I overlooked something; perhaps some error in calculations? If so I don't see it. Anyone? Ross

NEOWatcher
2009-Feb-10, 05:56 PM
...It doesn't appear that a close encounter with Earth can occur in 2044. Have I overlooked something; perhaps some error in calculations? If so I don't see it. Anyone? Ross
It looks like something changed or was a typo or something.
The UT story (http://www.universetoday.com/2009/02/07/new-potentially-hazardous-asteroid-discovered/) has 2044 crossed out and replaced with 2046.

Ross 54
2009-Feb-11, 12:14 AM
Thanks for your reply, NEO Watcher. The two orbit diagrams in the UT article match those of NASA quite well, and indicate an orbital period for 2009 BD81 of 1504 days. I'm assuming, for now, that the 1643 day orbit was based on preliminary data, and has since been revised. Using the 1504-day orbit, the whole of the year 2046 should see the asteroid moving outward from just outside Mars' orbit, working toward aphelion. No Earth encounter in that year either, it seems. The whole business appears rather odd. Ross

publiusr
2009-Feb-20, 08:15 PM
This needs to be watched.

fifelad55
2009-Feb-21, 02:14 PM
If my maths is correct (I'm still learning this) and using Kepler's 3rd Law, an orbital period of 1,504 days equates to a semi-major axis of 2.57 AU. If this asteroid is close to the orbit of Jupiter at aphelion, its perihelion would have to be very close to the Sun, much closer than Mercury's average distance.

Without knowing the aphelion distance, my guess is that this asteroid could come inside the orbit of Mars but is unlikely to pass close to the Earth unless its orbit is altered by Jupiter.

Alan

01101001
2009-Feb-21, 04:56 PM
JPL Small-Body Database: Orbit Diagram (http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20BD81;orb=1)

From about 4.1 AU out, down to about 0.935 AU.


This needs to be watched.

JPL Near Earth Object Program: NEOs Removed from Impact Risk Tables (http://neo.jpl.nasa.gov/risk/removed.html)


As the set of available observations for a given object grows we are often able to rule out previous potential impacts as no longer consistent with the observations. The following table gives a listing of such objects for which all previously detected potential impacts have been eliminated.

[Designation / date removed]

2009 BD81 2009-02-10 15:49

BigDon
2009-Feb-22, 11:21 AM
JPL Small-Body Database: Orbit Diagram (http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20BD81;orb=1)

From about 4.1 AU out, down to about 0.935 AU.



JPL Near Earth Object Program: NEOs Removed from Impact Risk Tables (http://neo.jpl.nasa.gov/risk/removed.html)

Thanks Binary Man!

Anybody know how big this critter happens to be?

selden
2009-Feb-22, 11:58 AM
Thanks Binary Man!

Anybody know how big this critter happens to be?

Its size is estimated in Nancy Atkinson (http://www.universetoday.com/author/nancy/)'s Universe Today article (http://www.universetoday.com/2009/02/07/new-potentially-hazardous-asteroid-discovered/) as 0.314 km (about 1000 ft.). That could be painful!

tony873004
2009-Feb-23, 03:33 AM
If the nominal trajectory is correct, 2009 BD81 is in a 3:1 resonance with Jupiter, similar to the orbit of Toutatis.