Re: Spaceships and astronomy
 

We usually always have clear skies here ...except the past few days.:(
Hopefully may clear by mid week. :fingerscrossed:

Re: Spaceships and astronomy
 

Earth has another moon! :blink:

NASA says it isn't, but then they're also trying to tell us that Pluto isn't a planet. :(

Re: Spaceships and astronomy
 

It's cool. It kind of is and it kind of isn't. It isn't a natural satellite like the Moon, but it obviously is in some kind of orbit around the Earth nonetheless.

Re: Spaceships and astronomy
 

Maybe it's the Iron Chicken!

https://photos.smugmug.com/photos/i-.../i-DNkb2hz.jpg

Re: Spaceships and astronomy
 

:lol:

Re: Spaceships and astronomy
 

There appears to be too little information to rule out that possibility at the moment. :lol:

It's interesting that we can look at stars that are billions of lightyears away/ years old, but we can suddenly find a sizeable chunk of rock that we didn't know is whizzing around in our own back yard. :huh:

Re: Spaceships and astronomy
 

It's a lot easier to see an elephant 50' away from you than a gnat under your nose.

Re: Spaceships and astronomy
 

I would use the word worrying. What's to stop it breaking orbit and crashing into us?!

Re: Spaceships and astronomy
 

Chances are it's likely to be moving away from us anyway, like the moon is, albeit very very slowly.

Anyway, Newton's first law is what is at work here. Unless it is pushed out of its orbit by some external gravitational influence, it will stay where it is quite happily. Even then it's a crap shoot as to whether said influence would not just push it out of orbit and away from Earth anyway.

More of a concern are as yet undiscovered or untracked Near Earth Asteroids, or unobserved comets from the Kuiper Belt stopping by to say hello. Luckily, Jupiter helps keep a lot of these objects away from us. We do love Jupiter :nod:

Re: Spaceships and astronomy
 

Physics! :thumbup:

Re: Spaceships and astronomy
 

Agreed, with statistics playing a strong supporting roll. :nod:

I have just done a rough calculation, based on an orbit of radius 9 million miles and a size of the earth as a disc of 8,000 miles across. If the asteroid flew off in a totally random direction, the probability of it coming in our direction (it hitting a disc of 50 million sqmiles on the surface of a sphere with the radius of its orbital distance from earth) is 1.64×10^-14, which I think is less than 1 in 60 trillion. In any case, the reality is that if it gets "nudged" it is far more likely to shoot off into space that come in our direction.

Re: Spaceships and astronomy
 

Depends on the direction of nudging. Earth gravity pull random non orbital objects in, if a large enough one hit the astroid the likely direction would be towards earth.

Re: Spaceships and astronomy
 

It wouldn't work like that in practice. A random object would have to be essentially on a collision course with Earth in order to come straight at us like that, at which point it wouldn't matter what it hits on the way.

Re: Spaceships and astronomy
 

I'm just thinking, many random objects are on a collision course with Earth, but get burned up in the atmosphere. If one were to hit the orbiting astroid (unlikely but possible) its trajectory would likely include a liaison with Earth.

Re: Spaceships and astronomy
 

The earth isn't big enough to be "pulling objects in" from more than 9 million miles away, it just isn't - that is the "physics" that Anian alluded to.

If anything gets close enough to that chunk of rock to move it out of earth's orbit it will (i) be pretty much random in direction, and (ii) is by far most likely to put it (back) into orbit around the sun, which is likely where it came from in the first place.
You've been watching too many sci-fi movies. :rolleyes: