Movement of stars, earth etc

kraggy

Hey guys, total amateur so bare with me..

Just wondering why the stars and their positions, relative to each other don't change even though we are moving around the sun. Since the angle from which we are viewing them is changing, shouldn't their positions relative to each other i.e. constellation shape, change also?

Or is it that they are just so far away that the change in angle is negligible?

Thanks,

K.

Spear

kraggy wrote: »

Hey guys, total amateur so bare with me..

Just wondering why the stars and their positions, relative to each other don't change even though we are moving around the sun. Since the angle from which we are viewing them is changing, shouldn't their positions relative to each other i.e. constellation shape, change also?

Or is it that they are just so far away that the change in angle is negligible?

Thanks,

K.

They do of course move, and it's the basis of the measurement, the parsec.

http://en.wikipedia.org/wiki/Parsec

But 2 AU's worth of movement isn't much compared to light years.

Kevster

It's just that they're so far away from us... The changes are subtle ones, unrecognisable to the naked eye. With telescopes, they can be measured though, but you'd have to be focussing on them for a very long time (wekks, months, etc) in order to pick up slight changes. That's for the 'really' far away ones.

kraggy

Thanks Kevster. Fairly new to astronomy. In fact, know very little bar a few constellations!

Thanks for that.

Was reading last night and amazed to discover that the solar system is rotating at great speed within the Milky Way but that the MW is so big that it takes the SS 260 million years to go all the way around. Interesting stuff. Might sound basic to you guys but I found that intriguing.

Going back to the stars, what is their movement? I mean, do they revolve around inside in the MW like the solar system does? Are the stars we see even in the MW?


Thanks again.

K.

Tzetze

Was reading last night and amazed to discover that the solar system is rotating at great speed within the Milky Way but that the MW is so big that it takes the SS 260 million years to go all the way around. Interesting stuff. Might sound basic to you guys but I found that intriguing.

Going back to the stars, what is their movement? I mean, do they revolve around inside in the MW like the solar system does? Are the stars we see even in the MW?

It's believed that the Milky Way is a Barred Spiral galaxy. The spiral arms rotate around the galactic centre. So yes, the other stars in the Milky Way rotate around like our own solar system does.

All the individual stars that we can see are part of the Milky Way. As far as I'm aware, it's not possible to resolve individual stars from other galaxies with current telescopes. All the work being carried out in the search for extrasolar planets is being done on stars in our own galaxy.

Spear

For the sake of comparison

http://en.wikipedia.org/wiki/Barnards_Star

check the .gif of it's motion over the years.

Kevster

Kraggy, as others have said, all of the stars you can see in the night sky are in the Milky Way. However, noty every point of light you see up there is a star. There is invariably a planet to be seen (Jupiter, Mars, Saturn, Vens, and Mercury can all be seen with the naked eye). Plus, some of those 'stars' are entierly different galaxies in their own right.

Download this programme dude: Stellarium

...You'll love it! I just know you will.

Kevin

Iridium

There's another really cool program called Celestia. It's sort of like a planetarium program, but instead of being on Earth it enables you to fly through space and see the positions of objects from any location in the solar system, and the galaxy at large. Would highly recommend it. And it's free.