First Earth Trojan Asteroid Discovered 173
The Bad Astronomer writes "Astronomers have found the very first Earth Trojan asteroid, a rock that more-or-less shares Earth's orbit around the Sun. Seen in data by NASA's WISE mission, 2010 TK7 is about 300 meters across and leads the Earth by 60 degrees around the Sun. Trojans have been seen for Jupiter, Neptune, and Mars, but this is the first for our planet."
Trojans! (Score:5, Funny)
... the very first Earth Trojan asteroid,
Curse its sudden but inevitable betrayal.
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... the very first Earth Trojan asteroid,
Curse its sudden but inevitable betrayal.
Now die!
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Ribbed for her pleasure TM.
L4 (Score:2, Insightful)
This one should be called 'Lagrange'
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Rumour spreadin' a-'round in that Texas town
'bout that rock outside La Grange
and you know what I'm talkin' about.
Just let me know if you wanna go
to that stone out on the range.
They gotta lotta nice girls ah.
Have mercy.
A haw, haw, haw, haw, a haw.
A haw, haw, haw.
Well, I hear it's fine if you got the time
and the ten to get yourself in.
A hmm, hmm.
And I hear it's tight most ev'ry night,
but now I might be mistaken.
hmm, hmm, hmm.
Ah have mercy.
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we should name it Dusty Hill
no surprise really (Score:2)
First thing that crossed through my mind when I read this, duuh, that's an L4 or L5 isn't it?
Probably the only reason it took them this long to "discover" it was its small size. After all, they knew exactly where to look.
Re:L4 (Score:4, Informative)
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Stephen Baxter's Titan [amazon.com] has an asteroid being used as a KE weapon.
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Niven and Pournelle were there first [wikipedia.org].
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E E 'Doc' Smith 'Lensman' series has pairs of PLANETS being used as a KE weapon
So now someone cite a scifi example of a solar system or galaxy used as a weapon?
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So now someone cite a scifi example of a solar system or galaxy used as a weapon?
E E 'Doc' Smith 'Lensman' series featured two galaxies colliding. Not sure if it was by design.
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Main concept missing from summary (Score:3)
The asteroid orbits one of the two Lagrangian points of stability of the Earth-Sun system
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If there are only 5 then why did it take so long to find this rock? Is it becaue the sun is between us an it? If so then there could be some real intersting stuff at that lagrange point.
because the rock is 300 meters wide... space is a lot larger than that. Also the sun makes it difficult to see from the ground
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yes but the sun would also give a glair on any ground-based telescopes...
Where would the Sun get egg whites?
If you mean glare, you'd be wrong. Astronomical darkness ends about an hour and a quarter before sunrise. This asteroid, because of its orbit, will rise precisely four hours before the sun. So you've got over 2.5 hours of dark in which it would be visible.
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But three of the Lagrange points are only stable in a plane perpendicular to the orbits of the two bodies making the point, they are not points of stable equilibrium for any displacement
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L2 is much closer to Earth than L4 or L5 is.
I like the proposed names (Score:3)
Intriguing (Score:3)
And here I thought that from what I've heard so far that Earth had possibly some dust or at most some gravel at its L4 and L5 points. This discovery of a sizable asteroid there makes the Earth's L4/L5 points much more interesting. Hopefully there is even more to be found!
There are additional moons to be found (Score:2)
I've always suspected that Earth has some additional tiny moons that haven't been discovered yet -- but my professors always pooh-poohed that idea, without really giving a good reason why.
Now it turns out that an Earth Trojan has gone undetected until now. This strengthens my belief that Earth has some miniature natural satellites awaiting discovery.
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Sorry but there are none now, early in the formation of the earth-moon system there would have been debris, but after a billion years would be either ejected or become part of earth or moon.
http://www.newscientist.com/article/dn13836-did-earth-once-have-multiple-moons.html [newscientist.com]
Funny that third stage of Apollo 12 was found orbiting as moon.
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well if you look at it's orbit it is orbiting the L4 in way that is out or our orbit plane.. so while it's stable it's also not exactly just sitting there.
When did it get there? (Score:2)
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and what's "First Earth" ?! (Score:2)
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This is madness!
THIS. IS. SPAAAAAACE!
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If it's a Trojan asteroid, does that mean it's full of space Greeks?!!!
No, it just means that Earth hasn't updated its antivirus (and, possibly, has a nasty habit of visiting promiscuous sites on the Internet).
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I'm going to give you the benefit of the doubt and assume you aren't trolling:
A Trojan Asteroid would be full of Greeks in the same way that the Trojan Horse was full of Greeks.
maybe it trails (Score:2, Funny)
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In a word? Vectors.
Whoosshh..
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Run Away!!! (Score:3, Funny)
Well, now, uh, Launcelot, Galahad and I, wait until nightfall, and then leap out of the asteroid, taking the French, uh, by suprise. Not only by suprise, but totally unarmed! ...*Who* leaps out?
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damnit. i came here just to make this joke.
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be sure to bring a herring with you. Never know if you'll need one.
VLBI (Score:3)
Who will be the first person to suggest placing VLBI radio telescopes at each lagrange point? Oh I guess it'll be me. A nice heavy asteroid would be convenient for vibration dampening WRT antenna pointing.
The problem is when/if we ever do planetary colonization, those L points will be in high demand for planetary relay satellites, as no matter where any other planet is in its orbit relative to earth's orbit, at least one earth L point should be in view... so what do we want there, sensitive receivers or big ole transmitters? I'm guessing we'll have some kind of scientific "quiet hours" scheme where the scientists get the first second of every minute, first minute of every hour, and first hour of every day, of radio silence. Or maybe they'll just be screwed?
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those L points will be in high demand for planetary relay satellites, as no matter where any other planet is in its orbit relative to earth's orbit, at least one earth L point should be in view... so what do we want there, sensitive receivers or big ole transmitters?
Or we could split them up: One Lagrange point for transmitters, one for receivers?
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Damn! Now I have an intense urge to put a 2m ham repeater at L4.
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Damn! Now I have an intense urge to put a 2m ham repeater at L4.
Hell, I have an intense urge to park a Winnebago at L4.
Trojan? Trojan? (Score:2)
Let's turn it into a space habitat (Score:3)
http://visions2200.com/SpaceHabitat.html [visions2200.com]
equilateral triangle? (Score:2)
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It's *almost* an equilateral triangle, if the earth's mass were totally negligible then it would be perfect e. triangle. Don't forget the earth-sun distance varies too, in elliptical orbit case you get lagrange area rather than point you get with circle.
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and meant to conclude with, the object is orbiting the lagrange area and not at it
Does this mean Earth is no longer a planet? (Score:2)
Does this mean Earth is no longer a planet like Pluto?
Planet requirements:
1. It needs to be in orbit around the Sun. (Check)
2. It needs to have enough gravity to pull itself into a spherical shape. (Check)
3. It needs to have “cleared the neighborhood” of its orbit. (Uh oh! Pluto doesn't satisfy this requirement and apparently now Earth doesn't either!)
Obviously I jest, but I do find it funny.
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Yes, jests are fun. But seriously, it would depend on how many decimal places before you agree to round up to "swept out". I think most people would be willing to round up in this case, but not in Pluto's.
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That is because the IAU passed an IDIOTIC politically motivated definition defined by a committee of washed out has-been scientists, that made absolutely no sense neither scientifically nor in the lay vernacular.
By this definition
- no extra-solar planet is actually a planet, since they don't orbit the Sun (aka Sol, OUR star). Why they couldn't replace "sun" with "parent star" or "primary graviationally bound star" is beyond me.
- a dwarf planet is not a planet either. (They needed to use another name for wha
Earth must be hung like a Roman god (Score:2)
300 meters across?
It's so big (Score:2)
The Trojan asteroid now comes with a fire & ice sensation.
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Given its position earth will never clear its orbit, but then I guess Jupiter shouldn't be considered one either as it also has an asteroids trapped at its Lagrange points, as does Neptune and Mars.
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Nope, putting small objects into a Lagrange point of stability is one way a planet clears its orbit.
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Planets can clear their orbits by placing things in their Lagrange points. Same way teenagers clean their rooms by shoving everything in the closet or under the bed.
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I learned that trick way before I was a teenager. under the dresser behind shield of shoes was a good place too.
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Since this trojan shows that the Earth hasn't cleared its orbit, does that mean that Earth is no longer considered a planet?
Being in a Lagrange point doesn't mean that the Earth hasn't cleared its orbit. Unless you want to argue that the presence of a moon means the Earth hasn't cleared its orbit. After all, the moon also roughly follows the orbit of the earth around the Sun.
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Given that the barycenter's center of mass is within Earth itself, I'm happy to call it Earth's orbit for simplicity's sake. Come to think of it, the only planet or dwarf planet whose satellite is massive enough to place the barycenter outside of the planet itself is Pluto.
I suppose that the astronomy and astrophysics communities could further refine the definition of planet based not only on size, but on the location of mass relative to a satellite...
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Agreed, I've come to think that Phobos and Deimos should be reclassified as gravitationally trapped debris or something along those lines.
To qualify as a satellite, using volume percentages would be problematic in the realm of gas and ice giant planets, so maybe something along the lines of spherical shape would be the way to go.
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The problem with the barycenter rule is that the Jupiter-Sun barycenter is outside the Sun. Do you delist it as a planet because it doesn't orbit the Sun, but a point outside the Sun?
What we really need to do is get rid of the idea that planets are going to be a short, enumerable list that elementary school students can memorize, and instead use it to mean any object, wherever it is, that's too small for its gravity to make it fuse but big enough to wind up in a round shape under its own gravity.
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The problem is big and massive are two different things, and it depends on the material composition of the object. So we will end up with objects that are in hyrdostatic equilibrium that are smaller in diameter / size than other objects that are not. Take asteroid 4 Vesta for instance, it's larger in diameter than several objects that are in hydrostatic equilibrium, yet it is not itself. Also there are plenty of moons that are in hydrostaic equilibrium, according to your definition these would be planets
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I know it's outside the surface of the sun, but the corona is no longer considered part of the sun?
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The barycenter of the Sun-Jupiter system lies at 1.068 Solar radii from the Sun's center... i.e. outside the Sun itself.
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1.068
As numbers go that one is right up there with the angle subtended by the Moon and the Sun from the Earth. The apparent orbital resonance between Mercury and Earth is a great joke too.
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Well, I guess that rule doen't apply to trojan points. Otherwise the list of planes would be quite small (4 now, but may quite well setle in 1 - Mercury - or 0 when we get better telescopes).
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could you elaborate, was that the clarity, taste, aroma or bouquet?
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It's not even necessarily about the size of other objects, but about the total mass of objects.
Pluto is a tiny fraction of the mass in its orbit.
Everything else in earth's orbit is a tiny fraction of it (not counting Luna).
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"In the end stages of planet formation, a planet will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence. A large body which meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which shares its orbital neighbourhood with Kuiper belt objects such as the plutinos. The IAU's definition does not attach specific numbers or equations to this term, but all the planets have cleared their neighbourhoods to a much greater extent than any dwarf planet, or any candidate for dwarf planet."
http://en.wikipedia.org/wiki/Clearing_the_neighbourhood
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Don't neglect the "gravitational dominance" aspect, which can be calculated using the Planetary Discriminant (also described on that page), and essentially subsumes the "comparable size" part. If there were other objects of comparable size, then these metrics would necessarily be much smaller.
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No planet has cleared it's orbit 100%, which is okay because that never was the requirement.
Earth has done the job of clearing its orbit 100,000,000 times better than Pluto has. it doesn't have to be perfect to clearly be in a different class.
Re:Isn't this a ticking time bomb? (Score:5, Informative)
No, the Lagrange points are stable garbage dumps for planets to put "small" things of 9% of its mass or less, the stuff stays there. It's one of the ways a planet clears its orbit.
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And if a LOT of stuff accumulates there - you get a new moon. Eventually.
That's how we got our favorite Luna, probably.
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Being that this is in the same orbit around the Sun as Earth and it will stay there, is this a viable location for a human colony?
First space colony would be the moon, then this asteroid, then Mars?
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...2010 TK7 is about 300 meters across...
It would be kind of cramped, and I rather suspect the gravitational pull would be negligible for all practical purposes.
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It would be kind of cramped, and I rather suspect the gravitational pull would be negligible for all practical purposes.
Assuming the same average density as Earth, the surface gravity would be about 1/50000 that of Earth. I make it 0.0002 meters/second squared.
...laura
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A significant fraction of the earth's density (~20%) comes from gravitational compression.
A smaller body with the exact same material composition as Earth would have lower density than the Earth does.
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Which means that if you fart while sitting on the Asteroid you'll reach escape velocity.
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No, the Lagrange points are stable garbage dumps for planets to put "small" things of 9% of its mass or less, the stuff stays there. It's one of the ways a planet clears its orbit.
Theoretically you are right. Practically, the orbit of TK7 is actually unstable. Because TK7 executes some Lissajous orbit around L4 and the Moon orbit is eccentric [wikipedia.org] (search for the "the case of the Earth-Moon system" in the linked page).
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If this were found at L3, that would sound about right.
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Thanks, I was trying to remember the name of that bad boy. Cruithne!
http://en.wikipedia.org/wiki/3753_Cruithne [wikipedia.org]
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Tell me.... Does it have oil?????
Yes, of snake variety. Wanna buy some?