Red planet fly-by: Comet Siding Spring swinging past Mars this Sunday

[n2doc]

The spacecraft around Mars are getting ready for a spectacular show next weekend as comet Siding Spring flies past the red planet at a distance of just 138,000 kilometres. That’s less than half the distance between Earth and the Moon, and ten times closer than any known comet-fly by of our planet.

The event on Sunday 19th October will be a rare chance for the orbiters studying Mars to get a good shot of a real-life comet in action around our solar system.

To add to the interest, Siding Spring is what’s known as an Oort Cloud comet, and it is on its first-ever trip into our inner solar system. That’s important, because all the other comets we have had close encounters with are what are known as periodic comets, that’s to say they have an orbital period of fewer than 200 years. Siding Spring has an orbital period of several million years.

As this is its first time this close to the Sun, it isn’t at all clear what will happen to Siding Spring. It could just fall apart, and leave everyone wondering what might have been. It could get dramatically brighter, or just fade away. You just never know with comets.


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http://www.euronews.com/2014/10/13/red-planet-fly-by-comet-siding-spring-swings-past-mars-/

Oh to be on Mars.....

[Gelliebeans]

1. Will there be a live feed?

[Callmecrazy]

2. Yes! Yes there will...

It will be hosted live by Sarah Palin on the surface of Mars.

[Gelliebeans]

3. Bout time

[Thor_MN]

4. So how do we know it's the first ever trip?

We haven't been around that long, after all...

[FogerRox]

5. The probably cumputed the orbit

In rough form only 3-4 observations are needed to do the math. IT came from the Ort Cloud, near the perimeter of our Solar System .

Siding Spring has an orbital period of several million years.

[Thor_MN]

6. With the age of the Solar system at several billion years

That's enough time for hundreds of passes close to the sun...

See what I'm saying?

[FogerRox]

8. Depends when its orbit got perturbed

to kick it into the slow fall towards the sun. Its very possible that this one got kicked out 2-3 million yrs ago.

[Thor_MN]

9. Possible, yes. Probable? Who knows?

I'm just curious why people are so confidently saying this is its first pass close to the sun. Seems to me that we would have no clue... After all, it's not like we have been recording events in the sky for several million years.

[FogerRox]

10. Its orbit tells us very accurately where it came from.

We have a major clue. Its orbit tells us very accurately where it came from, and how long it took to get here. There are trillions of icy bodies in the Ort Cloud. In the life of a solar system, its happened recently, Comet Hale Boop was visible from the 2nd half of 1995 thru 1997, and had a very odd orbit.

http://en.wikipedia.org/wiki/Comet_Hale%E2%80%93Bopp#Orbital_changes

[Thor_MN]

11. Its orbit tells us that its period is about a million years

That leaves plenty of time for it to have been this way hundreds of times...

Restating that they have measured it's orbit accurately does not change that.

I'm not trying to be argumentative, but there's no answers as to why they are saying it is the first pass in your post or link. Once it has gons by and they have studied the noble gas ratio, they may have some more ideas, but that's sounds like there's a significant amount of uncertainty due to lack of knowledge of it's original composition.

[RussBLib]

7. it's so freaky

...to think that at practically any given moment, a previously undetected comet or meteor could hit the Earth, causing extreme damage. And every religion on Earth would likely claim that God was punishing mankind for some perceived offense.