My first thread here, about constellation

[ThomasJoe40]

Hello, all,

I guess this must be a very shallow question to most of you guys as I am a new comer to this forum.

As I found that the universe far far larger as I imagined, all the stars in the star chart must only belongs to our galaxy, so are all the constellations also belong to our galaxy?

A shallow question, thanks for reading it. :rofl:

 

[turbo]

That's actually a very good question. Yes, the stars you see on your charts belong to our Milky Way Galaxy, and most of them are in our neighborhood of this galaxy. The constellations are made up of stars that are bright and easy to view. Some of them are modest-sized and closer to us, and some are much farther away, but are much brighter too. The stars in any given constellation can be VERY different distances from us, even though they appear to be physically close to one another.

Welcome to the forum!

 

[chroot]

Hi ThomasJoe40, welcome to physicsforums.com.

It's not a shallow question at all.

The constellations are not groups of stars, contrary to common belief. The constellations are actually areas of the sky as seen from Earth. The constellations actually have boundaries, much like state or nation boundaries look on a map. The constellations interlock and cover every point in the sky in much the same way that the countries on a map cover every bit of land. Every point in the sky belongs to exactly one constellation, even if there are no stars at that point.

You are correct in assuming that all of the stars you see in the night sky are within our own galaxy. You can see a few other galaxies with your naked eye, such as the Andromeda galaxy, but it's much too far away to allow you to see individual stars in it.

- Warren

 

[ThomasJoe40]

Thank you, guys... the information you provided give me a brand new view about the star chart.

So, it is also possible to view some stars from other galaxies by our naked eyes, that sounds so cool...

Thanks, guys, I feel very happy with my first thread. :rofl:

 

[Tom McCurdy]

What strength telescope is needed to see a star of another galaxy?

 

[chroot]

Thank you, guys... the information you provided give me a brand new view about the star chart.

Glad to help.

So, it is also possible to view some stars from other galaxies by our naked eyes, that sounds so cool...

It's quite possible -- you can walk outside and take a look at the Andromeda galaxy. It's huge, about 5 times the diameter of the full moon, and looks like an elongated glowing smudge. It's visible in reasonably dark skies. If you live in a city, though, the light pollution around you will make it impossible to see with the naked eye.

It's very difficult to see individual stars in a distant galaxy, in much the same way that it's very difficult to see individual grains of sand in a distant beach. Some special kinds of events, however, like novae and supernova, can make an individual star shine very very brightly for a few months, allowing one to see it individually through even a modest telescope.

- Warren

 

[ThomasJoe40]

Glad to help.

It's quite possible -- you can walk outside and take a look at the Andromeda galaxy. It's huge, about 5 times the diameter of the full moon, and looks like an elongated glowing smudge. It's visible in reasonably dark skies. If you live in a city, though, the light pollution around you will make it impossible to see with the naked eye.

It's very difficult to see individual stars in a distant galaxy, in much the same way that it's very difficult to see individual grains of sand in a distant beach. Some special kinds of events, however, like novae and supernova, can make an individual star shine very very brightly for a few months, allowing one to see it individually through even a modest telescope.

- Warren

Oh, thanks again... kkk, I was quite busy at the moment for finding an accommodation at London as I am going to be a freshman at UCL in Physics and Astronomy Department, how excited...!

So, after sorry for my late reply, I would really like to ask that what could be possibly seen by in a real observatory, of course in a reasonably dark and cloudless sky? As I will have a chance to go the the University of London Observatory every week, I was really excited about to observe the Andromeda galaxy by a big telescope¬¬ :tongue2:

Thanks for your reply again, haha¬¬ (Are you an astronomy expert in a university, I am really wondering... )

 

[Nereid]

This may sound funny, but astronomers rarely, if ever, actually *look* through observatory telescopes! The big modern beasts, such as the Kecks, the Geminis, the VLTs, Subaru, ... all have very expensive, very fancy instruments attached where one would normally put one's eye - cameras, spectroscopes, and more. Even the guiding is done by a TV-type camera hooked up to a guide 'scope.

The reason? The human eye is a very poor detector, for the kind of quantitative science that astronomy now is. For example, CCDs (which are the devices in your favourite digital camera) are far more sensitive than the eye, and have a nearly linear response.

So, while the view would certainly be impressive, you won't see the same thing as all the beautiful images, at Astronomy Picture of the Day, for example.

 

[turbo]

This may sound funny, but astronomers rarely, if ever, actually *look* through observatory telescopes! The big modern beasts, such as the Kecks, the Geminis, the VLTs, Subaru, ... all have very expensive, very fancy instruments attached where one would normally put one's eye - cameras, spectroscopes, and more. Even the guiding is done by a TV-type camera hooked up to a guide 'scope.

Nereid's right about the BIG scopes, ThomasJoe40. Luckily for you, lots of universities have observatories that house venerable old (large, by amateur standards) telescopes that are eminently usable as visual instruments, despite the light-pollution and weather problems at the campus. I'm willing to bet that your college's observatory has some nice telescopes, and that you will have a fine time with them.

My college had an 8" Alvan Clark refractor on a massive mount. I own a 6" f:8 Astro-Physics APO refractor and love it. The views I get with it in dark-sky central and northern Maine sites are far superior to what I saw through the Clark located in a well-lit (read light-polluted) college campus, but I would not have traded those views for anything. Take full advantage of your school's vintage telescopes! You will gain a familiarity and love for the night sky that will drive you for years to come. Yes, your eyes are poor receptors, but they are YOURS and the immediacy of your observations will mean a lot to you.

If you love astronomy, please volunteer to learn the operation of your school's old scope(s) and volunteer to operate the scope on public nights, and most importantly, learn the night sky, so you can slew to objects quickly without depending too heavily on setting circles, etc. You will hook a lot of people into astronomy if you can maximize their time at the eyepiece and minimize the "fiddling around".

 

[ThomasJoe40]

Nereid's right about the BIG scopes, ThomasJoe40. Luckily for you, lots of universities have observatories that house venerable old (large, by amateur standards) telescopes that are eminently usable as visual instruments, despite the light-pollution and weather problems at the campus. I'm willing to bet that your college's observatory has some nice telescopes, and that you will have a fine time with them.

Thanks

My college had an 8" Alvan Clark refractor on a massive mount. I own a 6" f:8 Astro-Physics APO refractor and love it. The views I get with it in dark-sky central and northern Maine sites are far superior to what I saw through the Clark located in a well-lit (read light-polluted) college campus, but I would not have traded those views for anything. Take full advantage of your school's vintage telescopes! You will gain a familiarity and love for the night sky that will drive you for years to come. Yes, your eyes are poor receptors, but they are YOURS and the immediacy of your observations will mean a lot to you.

So, Maine must be a great place for observing stars. I was really envy that America has for such a huge territory, so that lots of place wouldn't have light pollution.

If you love astronomy, please volunteer to learn the operation of your school's old scope(s) and volunteer to operate the scope on public nights, and most importantly, learn the night sky, so you can slew to objects quickly without depending too heavily on setting circles, etc. You will hook a lot of people into astronomy if you can maximize their time at the eyepiece and minimize the "fiddling around".

Oh, Turbo-1, thank you so much for your kind suggestions, I will definitely do as what you said.

 

[ThomasJoe40]

This may sound funny, but astronomers rarely, if ever, actually *look* through observatory telescopes! The big modern beasts, such as the Kecks, the Geminis, the VLTs, Subaru, ... all have very expensive, very fancy instruments attached where one would normally put one's eye - cameras, spectroscopes, and more. Even the guiding is done by a TV-type camera hooked up to a guide 'scope.

The reason? The human eye is a very poor detector, for the kind of quantitative science that astronomy now is. For example, CCDs (which are the devices in your favourite digital camera) are far more sensitive than the eye, and have a nearly linear response.

So, while the view would certainly be impressive, you won't see the same thing as all the beautiful images, at Astronomy Picture of the Day, for example.

Sorry for my very very late reply and thanks for the website. So, could you tell me that are the Kecks, the Geminis, the VLTs, Subaru... telescopes, or sth else, cos I only knew that Gemini is a space probe that back to the Earth few weeks ago.

Looking forward for your reply! :tongue2:

 

[Nereid]

http://www.subaru.naoj.org/ .

 

[turbo]

Oh, Turbo-1, thank you so much for your kind suggestions, I will definitely do as what you said.

You are very welcome. I suggested that you offer your volunteer services because
1) you will get to use really nice old scopes for free
2) you will get to learn the basics of observational astronomy. This is an art that is quickly being lost, as computer-controlled scopes with remote guiders and sensors take over.
3) you will get to learn the night sky in a way that the computer-guided folks will never appreciate. Star-hopping and chart-reading will get you anywhere you want to go, even with NO drive.
4) you will learn to love this kind of observing, and your enthusiasm will kindle the interests of countless people.

I had a very cheap Newtonian reflector that I got when I was about 10 (in 1962). It was poorly built with poorly-figured optics and a flimsy mount. It was the best that my parents could afford and I loved it. When I entered college in 1970, I visited the university's observatory on student nights, and I truly appreciated the efforts of the student operators who could properly operate that nice old refractor. On nights when the seeing was steady, the planetary views were great (that scope's strong point!)

 

[ThomasJoe40]

http://www.subaru.naoj.org/ .

Oh, thanks, actually I have known these observatories for a while but just don't know their names. I have already put those websites into my favourite¬¬ :rofl:

 

[Phobos]

Welcome to Physics Forums, ThomasJoe40

cos I only knew that Gemini is a space probe that back to the Earth few weeks ago.

I think you mean the "Genesis" probe.

 

[ThomasJoe40]

Welcome to Physics Forums, ThomasJoe40



I think you mean the "Genesis" probe.

Oh, yes, that is Genesis... the probe that fell on the ground, by the way, has anyone heard about anything about this probe? :tongue2: