space questions

[Damocles]

I think I thought of meteors and asteroids as just going anywhere they wanted, silly really if I'd have just thought more about gravity.

They orbit the Sun like everything else.

If you think of the Solar System as a sphere in space with the Sun in the middle, then everything in that sphere will generally orbit around it (with the exception of Moons). The Oort Cloud is around the limit of that sphere - a place where many comets live that were never pulled into the middle to form planets and Moons. Sometimes due to gravity from objects outside of our Solar System (our Sun isn't stationary, it orbits the centre of the galaxy once every 250 million years or so just like we orbit the Sun), things get dislodged from that cloud and travel into the middle. This then starts and orbit which can last thousands and thousands of our years.

Many times it can cross the path of the orbit of a planet or whatever but it never hits it because it only comes round once every few thousand years and the planet wasn't in its path at that time, so the danger isn't exactly gone, it is just gone on our small Solar System scale.

That Men in Black analogy is extremely useful in how you visualise things because from our perspective the Solar System is this great big thing but from the perspective of looking at the Sun's orbit around the centre of the galaxy, we're just Moons of the Sun. And of course galaxies as a whole have their own shifts due to other galaxies near them. Our Milky Way galaxy is currently colliding with Andromeda. Obviously due to the great distances between things nothing will actually collide and it will take 4 billion years to happen but that is a good example of something upsetting the balance that our Solar System has already

(Artist's impression) Picture of the Oort Cloud:

[bigimg]http://www.utahpeoplespost.com/wp-content/uploads/2015/01/inner-oort-cloud.gif[/bigimg]

Milky Way

[bigimg]https://itzhakts.files.wordpress.com/2014/01/galaxy.jpg[/bigimg]

NASA simulation of galactic collision

[video]http://upload.wikimedia.org/wikipedia/commons/transcoded/c/cc/Andromeda_and_Milky_Way_collision.ogg/Andromeda_and_Milky_Way_collision.ogg.480p.webm[/video]

It's worth remembering after that that humanity's greatest space achievement is reaching the Moon.

 

[SkyBlueFlux]

Anybody who's interested in astronomy and wants to build their knowledge up from base, I'd recommend considering subscribing to Crash Course on YouTube because they've just this week started a new Crash Course Astronomy series. It's hosted by Phil Plait who I'm informed is a relatively well known astronomer in American circles who's worked on projects like the Hubble telescope.

For those who've never heard of Crash Course it's a channel primarily hosted by the vlogbrothers Hank & John Green and it won't be for everybody because it's aimed at quite a young demographic (I'd say mostly late teens/early twenties). They run courses on a variety of subjects, split up into easy to digest lessons. They're easy-watching and pretty engaging, I really got stuck into their World History series.

Don't know how good this one will be but definitely worth keeping an eye on to see if it piques your interest:

[video]http://www.youtube.com/watch?v=0rHUDWjR5gg[/video]

 

[Damocles]

Anybody who's interested in astronomy and wants to build their knowledge up from base, I'd recommend considering subscribing to Crash Course on YouTube because they've just this week started a new Crash Course Astronomy series. It's hosted by Phil Plait who I'm informed is a relatively well known astronomer in American circles who's worked on projects like the Hubble telescope.

For those who've never heard of Crash Course it's a channel primarily hosted by the vlogbrothers Hank & John Green and it won't be for everybody because it's aimed at quite a young demographic (I'd say mostly late teens/early twenties). They run courses on a variety of subjects, split up into easy to digest lessons. They're easy-watching and pretty engaging, I really got stuck into their World History series.

Don't know how good this one will be but definitely worth keeping an eye on to see if it piques your interest:

[video]http://www.youtube.com/watch?v=0rHUDWjR5gg[/video]

I'm a big fan of their World History series too. Didn't know they had started a new one, definitely going to watch that.

Phil Plait is well known in internet circles. He runs the Bad Astronomy blog, which highlights scientific inaccuracies in movies and TV and stuff. Worth a read actually as much of it is tongue in cheek

<a class="postlink" href="http://www.badastronomy.com/bad/movies/index.html" onclick="window.open(this.href);return false;">http://www.badastronomy.com/bad/movies/index.html</a> for his movie reviews, his blog is at <a class="postlink" href="http://www.slate.com/blogs/bad_astronomy.html" onclick="window.open(this.href);return false;">http://www.slate.com/blogs/bad_astronomy.html</a>

Worth a follow on Twitter aswell

EDIT: Apparently he's also the new President of the James Randi Foundation and a revered skeptic.

 

[SkyBlueFlux]

Anybody who's interested in astronomy and wants to build their knowledge up from base, I'd recommend considering subscribing to Crash Course on YouTube because they've just this week started a new Crash Course Astronomy series. It's hosted by Phil Plait who I'm informed is a relatively well known astronomer in American circles who's worked on projects like the Hubble telescope.

For those who've never heard of Crash Course it's a channel primarily hosted by the vlogbrothers Hank & John Green and it won't be for everybody because it's aimed at quite a young demographic (I'd say mostly late teens/early twenties). They run courses on a variety of subjects, split up into easy to digest lessons. They're easy-watching and pretty engaging, I really got stuck into their World History series.

Don't know how good this one will be but definitely worth keeping an eye on to see if it piques your interest:

[video]http://www.youtube.com/watch?v=0rHUDWjR5gg[/video]

I'm a big fan of their World History series too. Didn't know they had started a new one, definitely going to watch that.

Phil Plait is well known in internet circles. He runs the Bad Astronomy blog, which highlights scientific inaccuracies in movies and TV and stuff. Worth a read actually as much of it is tongue in cheek

<a class="postlink" href="http://www.badastronomy.com/bad/movies/index.html" onclick="window.open(this.href);return false;">http://www.badastronomy.com/bad/movies/index.html</a> for his movie reviews, his blog is at <a class="postlink" href="http://www.slate.com/blogs/bad_astronomy.html" onclick="window.open(this.href);return false;">http://www.slate.com/blogs/bad_astronomy.html</a>

Worth a follow on Twitter aswell

EDIT: Apparently he's also the new President of the James Randi Foundation and a revered skeptic.

I thought I recognised him even though I've not seen any of his documentaries, I'm guessing that's where I've seen him before.

Definitely going to check out Bad Astronomy though, sounds right up my street, cheers.

 

[TangerineSteve17]

A quick question. I read recently about how the ancients determined how far away the moon was. I didn't understand it at the time and now I can't find the page. Been looking for ages. It was something like phalanx, i have searched this and it has yielded no results. It isn't the right word obvioulsy. I wanted to look it up, anyone know what the word might be?

 

[Damocles]

A quick question. I read recently about how the ancients determined how far away the moon was. I didn't understand it at the time and now I can't find the page. Been looking for ages. It was something like phalanx, i have searched this and it has yielded no results. It isn't the right word obvioulsy. I wanted to look it up, anyone know what the word might be?

They used their thumb. If you can measure the distance between your eye and your thumb and see that your thumb covers the Moon, you can estimate the distance the Moon is away from the Earth pretty accurately.

I think what you're referring to though was Hippoarchus and him using parallax from two points to determine distance.

 

[TangerineSteve17]

Ah cheers mate yes, parallax not phalanx :) i couldn't find it again.

 

[TCIB]

Since you mentioned it, the phalanx gun system...

[video]https://www.youtube.com/watch?v=ILcVt9p7cug[/video]

[video]https://www.youtube.com/watch?v=VQ6YChXRn_A[/video]

 

[Zubrman]

A quick question. I read recently about how the ancients determined how far away moon was. I didn't understand it at the time and now I can't find the page. Been looking for ages. It was something like phalanx, i have searched this and it has yielded no results. It isn't the right word obvioulsy. I wanted to look it up, anyone know what the word might be?

They used their thumb. If you can measure the distance between your eye and your thumb and see that your thumb covers the Moon, you can estimate the distance the Moon is away from the Earth pretty accurately.

I think what you're referring to though was Hippoarchus and him using parallax from two points to determine distance.

Can you explain the thumb measure thingy, Damo? I can't see how it works because if one is looking at a horse and a building which are both the same distance away, your thumb may seem to cover the horse, but not the building?

 

[Zubrman]

A quick question. I read recently about how the ancients determined how far away moon was. I didn't understand it at the time and now I can't find the page. Been looking for ages. It was something like phalanx, i have searched this and it has yielded no results. It isn't the right word obvioulsy. I wanted to look it up, anyone know what the word might be?

They used their thumb. If you can measure the distance between your eye and your thumb and see that your thumb covers the Moon, you can estimate the distance the Moon is away from the Earth pretty accurately.

I think what you're referring to though was Hippoarchus and him using parallax from two points to determine distance.

Can you explain the thumb measure thingy, Damo? I can't see how it works because if one is looking at a horse and a building which are both the same distance away, your thumb may seem to cover the horse, but not the building?