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Evidence For 200-Year-Old Comet Impact On Neptune
astroengine writes "Astronomers using ESA's Herschel space observatory have spotted evidence of a cometary impact in Neptune's upper atmosphere (publication, PDF). Whereas impact craters on rocky planetary bodies can remain for billions of years, an impact in the dynamic atmospheres of gas giants aren't obvious, especially if long periods of time have elapsed. This ultimate 'cold case' tracked the unusual distribution of carbon monoxide in Neptune's stratosphere, a sure sign it was deposited there by an external source. Once they realized they were looking at a comet impact, researchers were able to deduce when the impact occurred: 200 years ago."
This would be much more interesting if it was about Uranus.
I agree with Fox "News".
This is just another way that Barack Obama is putting black people ahead of white people.
Obama is a racist. Fox "News" is doing us all a big service.
On Earth ... 200 years ago ... I was a prince... with power over millions...
Take that, comet!
Rhymes that keep their secrets will unfold behind the clouds.There upon the rainbow is the answer to a neverending story
a way to spend win Out; 3ither the
Note that this hypothesis is more plausible than it might seem at first glance since we've seen comets impact gas giants before. Most famously, in 1994 Shoemaker-Levy 9 was observed directly impacting on Jupiter http://en.wikipedia.org/wiki/Comet_Shoemaker-Levy_9. This also isn't the first time this sort of technique has been used to detect historic comet impacts. As TFA notes, this technique was previously used to show that a similar event likely occurred around 230 years ago on Saturn.
Although comets hit the outer planets frequently, this is due to a variety of issues including the large size of the planets and the exact orbit of Jupiter (which makes Jupiter very effective at clearing interplanetary debris). Thus, this sort of situation doesn't pose much of a risk for Earth. However, even a single such comet colliding with Earth would be an extinction level event. The asteroid that caused the Chicxulub crater in the Yucatan is generally estimated to be around 10 km diameter and most comets are generally larger than that (Halley's Comet has a mean diameter of 11 km, and many have larger mean diameters). Comets are also much easier to spot generally than asteroids and so we have a better idea about their orbits and are more likely to have a lot of warning before a potential impact event on Earth. Asteroids are much harder to see and pose much more of a threat even though they are smaller objects (with the exception of a handful such as Ceres).
We are rapidly learning more about the cometary impact rate on Jupiter, and now Neptune. It should be possible to extrapolate from this to calculate the impact rate on Earth.
Clearly, a dangerous object spends some time orbiting across the orbits of the planets before it hits something, and the probability of an impact on Jupiter is much greater than an impact on Earth.
We seem to be getting a handle on the risk from asteroids, but a comet can come our way without warning.
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ok?
what new does this tell us?
nothing
move along.
Did they find water? After all, we're talking about Neptune.
... and it also wiped out any dinosaurs that were there...
Bill Stewart
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That's funny, because I see coded racism every day on Fox "News", Rush Limbaugh, and all the other racist tea party heroes.
Not every person at a tea party is a racist, but almost every tea party has a few racists in attendance.
Some of them question Obama's birth certificate. Some rail against 'welfare queens'. Others just carry a gun, and let that do the talking. Some even claim that 'the other side', or the NAACP, by which they mean black folks are themselves racist. What did white southerners ever do to black people in America anyway??
They all have a racist coded message that anyone who stops to think about it would easily understand.
Perhaps this is why we have never seen any Neptunians?
If that was 200 earth years ago that the comet hit, then Neptune has made less than 1.5 orbits around the sun since then.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
When the comet Shoemaker-Levy 9 hit Jupiter sixteen years ago, scientists all over the world were prepared: instruments on board the space probes Voyager 2, Galileo and Ulysses documented every detail of this rare incident.
That's funny, because my back-of-the-napkin estimate is that at the time, Voyager 2 was 3 billion miles further away from Jupiter than the Earth is. Wonder what they thought they were gonna see with 15-year-old technology that they weren't going to see with, say, the Hubble telescope, new ground-based instruments, or hell, even the naked eye that was 3 billion miles closer to the event.
That's funny, because my back-of-the-napkin estimate is that at the time, Voyager 2 was 3 billion miles further away from Jupiter than the Earth is.
Evidence For 200-Year-Old Comet Impact On Neptune
I thought most comets were much older than 200 years. How does a comet form, and crash, in a mere 200 years?
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
If the moon kingdom had a damned militia this wouldn't have happened....
Instead they put all their funding for palaces built in the inhospitable airless vacuum that is the surface of the moon. Instead of building some sorta real defense force...
Tsukasa: All I really want, is to be left alone...