Help again

[Jingguo]

Hi guys thanks 4 the help the last time round. Here some more qes. Is it true that our galaxy look like andromeda ?? is the sun in the middle of the our galaxy?? what will happen to a nebula after a few millions yrs?? whats actually is dark nebula??? example-bernard 29 in auriga. Is sct-8 a good choice scope for viewing deep sky object n double star?? how is $ being pay to d scope dealer??? do they accept cheque or cash? how is oversea online transation being made when we don even c the buyer or d dealer??? thanks alot

[Vince]

Yes, it's true that our own galaxy, the Milky Way is similar (in terms of shape) to the Andromeda Galaxy. However, the sun is about 2/3rds away from the centre or core of the galaxy.

If our sun was in the centre, we'd be sucked into what many astronomers and physicists think is a super massive black hole.

P.S. It'd be a lot less messy for people to read your questions if they were put out in point or paragraphed form.

[Sam Lee]

What will happen to a nebula after a few million years?

I believe that after a really long period of time, a diffused nebula (eg. Orion Nebula) or a nebula that stars are borned in, will become more and more sparsed as the hydrogen gases has been used to create stars. Eventually, they will become something like the faint nebulosity which you see around M45 (Peleides).

What is a dark nebula?

First of all, why does nebula shines? That's because its either heat up by nearby stars (which is the case for Orion Nebula) or reflection of light from other stars. In case of a nebula which is not fortunate enough to have any nearby star to heat itself up or to reflect light from, it is not able to light up. NOW, normally we don't see these nebulas at all. But if the dark nebula happens to stand in front of another bright nebula, you can see that is casted a dark shadow in front of the nebula (which is the case for the Horsehead Nebula in Orion).

Hope that'll help! 8)

Regards,
Sam

We are the Borg, Resistance is Futile.

[acc]

Hi guys thanks 4 the help the last time round. Here some more qes. Is it true that our galaxy look like andromeda ?? is the sun in the middle of the our galaxy?? what will happen to a nebula after a few millions yrs?? whats actually is dark nebula??? example-bernard 29 in auriga. Is sct-8 a good choice scope for viewing deep sky object n double star?? how is $ being pay to d scope dealer??? do they accept cheque or cash? how is oversea online transation being made when we don even c the buyer or d dealer??? thanks alot

Hi Jingguo
To get better response to your multiple queries, do split them up and post them under meaningful subject headings under the correct sub-forums. For example, your query on the 8" SCT should appear in the equipment forum instead of here. This will help to maintain the orderliness of the site. Thanks.

cheers
cc

[Airconvent]

hi jingguo
I'll answer some of the other questions:

"what will happen to a nebula after a few millions yrs??"
It depends on whether the nebula is forming or dissipating!
If the nebula is in its birth, then most of its constituents will eventually collapse to form stars, leaving a thin wisp of cloud or none at all. In the case of a supernova explosion, most of the star's matter is thrown out into space and it expands at high speed as an expanding nebula. The Crab Nebula, M1 is one such supernova remnant. In such a case, the dust cloud expands until it is too diffuse to be seen...

"whats actually is dark nebula??? "
Dark Nubula is actually a great cloud of dust particles obscuring what we can see in the background. As what Sam mentioned, the most famous example would be Horseheard Nubula in Orion.

as for purchases from local vendors, for small items, I would presume they want cash. Unless you buy expensive stuff but even then, they may not want to take cheques for fear of fraud. I once have a chap who insisted to write me a cheque for a $10 purchase ! I asked him to go to field in Marina south....

rich