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Monday, November 07, 2011


Asteroid 2005 YU55 will not hit the Moon either

Left image: Orbit of 2005 YU55 at closest approach as seen from above. Right Image: Orbit of 2005 YU55 at closest approach as seen from the side. The asteroid is significantly above the plane of Earth's orbit. Simulated in Celestia (Click to embiggen).



Animation of the trajectory of asteroid 2005 YU55 compared to the orbits of the Earth and the Moon on 8-9 November 2011. Image credit NASA/JPL

Richard Hoagland has been saying that asteroid 2005 YU55 will hit the Moon.

His reason for saying this, apart from some numerical co-incidences which are just that, coincidences (perihelions of YU55 2011-09-09.8, C2010 X1 is 2011-09-10.7, spooky), is that the "close" encounter of Comet C/2010 X1 Elenin and YU55 changed YU55's orbit.

Unfortunately for his thesis, at that time Elenin was a stream of dust and rubble not up to deflecting the orbit of anything much. Also, we know that a close encounter between Comet Elenin when it was still intact and the asteroid 1999 RQ176 failed to deflect that asteroid.

Now, 1999 RQ176 is roughly 3 km in diameter compared to 0.4 Km for 2005 YU55, but it was also 100 times closer to Elenin (0.002 AU compared to 0.2 AU for Elenin and YU55) and gravitational force falls off as the square of the distance, so the gravitational deflection of YU55 by Elenin will be for all practical purposes non-existent.

And you would need substantial deflection, look at the animation above (and see also here), to hit (or zoom just above) the Moon would require a significant change of orbit, not just the minuscule deflection an incoherent cloud of dust could cause. What I wrote of YU55 and Earth applies here; a 50% margin of difference in the orbit would still cause the asteroid to miss the Moon by 120,000 Km.

As well, it has to twist the orbit completely, the plane of the asteroids orbit lies above that of the Earth and Moon (see diagrams above and here). To cause that big an orbital change requires a large gravitational filed, not the field of a cloud of dust.

But then again, Richard Hoagladn thinks that the "encounter" between Elenin and YU55 is "intelligently designed" to communicate a message to us.

Frankly, I think alien intelligences have better ways of communicating than with a game of cosmic billiards

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What if the asteroid starts revolving around the Earth and becomes our 2nd moon ? Is it possible ?
The trajectory of the asteroid (and anything else in space) is ruled by kepler laws. Once the trajectory is known (as showed here above), the object can't go elsewhere.
That's why it can't be satellized around Earth
dude what if nasa's trajectory is not correct? what if they lie to us on purpose? you never know?
It's not NASA's trajectory, it's the trajectory worked out by the astronomical community. NASA uses the data from the astronomical community to do its orbits for the simulation, but the observations and orbits come form the astronomical community and not NASA.

You can, with the raw data on the Minor Planet Ephemeris Centre pages (astronomers, not NASA), work out the orbit for yourself.

And we would know, we, the amateur astronomers of the world, contribute the data to get these orbital solutions, and we can calculate them ourselves (and do). We would know instantly if someone is lying.

Why this obsession with NASA?, NASA is not the lord high PooBah of astronomy, it covers spacecraft and has excellent outreach, but it does not dictate to the world of astronomy.
I know this is out of the context, I also wrote a comment on your other article about the 2005 YU55 asteroid, but what is all this buzzz about Dec 21, 2012? Could any of that be true? I tried to find some answers, but I cannot find the right source to give me a good answer, and I am not sure where to look. It seems that people have lots of theories but no-one has some good facts.
Oh, and I think the obsession with NASA is "movie" based, mainly when you live in the US. I live in TX and many Americans, including myslef at times, have this fear that the Government keeps the truth away from the people.
Remember that NASA can't lie to us (amateur astronomers). We have the tools to verify what they say and the knowledge of how space objects behave.
Since decades, nobody has ever been seen lying, although we are plenty to check.
We are thousands around the world with big telescopes. We survey asteroids and comets for them, we can do the calculations for them. The astronomers community is connected with Twitter, Facebook and others ... We are able to raise alerts ! And we do for each discovery.
If one day an asteroid is not EXACTLY at the place it should be in the sky, we will raise an alert. But we never do that because trajectories are really accurate and space objets do not decide to change their path. They follow physics rules that are simple and well well known. No surprise with trajectories...

And as Ian said, NASA is not responsible for everything in astronomy. There are plenty of other groups doing the same good job. For example, Elenin's survey was not part of NASA's job, that's why you saw only amateurs talking about this comet and not NASA.
But for hoagland elenin was not a comet, but a technology and was not destroyed from the cme..too distant..(from the point of view that it wasn't a comet)
Hoagland is a snakeoil salesman of the highest order. No need to bring in the tomato plants just yet.
RCHoagland is having a hard time these days... :) 1st it was the 'spaceship' Elenin -a strange comet-not-comet for him, 2nd here it comes another 'spacetruck' called YU55, both 'intelligent' both 'by design' both 'strange'... Well, when 2005 YU55 disappears w/o making a hole in the moon, Hoagland soon will get another 'controlled' object to play with. :)
Unless something stole the mass away it doesn't actually matter whether Elenin was in one piece or all in pieces - it still did not have enough mass to change the orbit of anything except another nearby small comet or asteroid.
That's what annoyed me about Deep Impact - the mass was still coming.
But I'm always pedantic about things like that.
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