Questions about the Sun and other stars

[Doc]

Wow amazing video but where's Uranus.

[bish]

Great video - like you say it's very difficult to comprehend the size of these little dots of light shining in the sky!

[AstroTiger]

To clarify, yes there are "planets" orbiting other stars, we know this from images which have been taken.

Currently, we dont have the technology as yet to resolve this as anything other than tiny dots.

Once we do i am sure we'll be quiet surprised to learn what orbits other stars.

[JamesK]

Wow amazing video but where's Uranus?

Must... resist...

Uranus is to large to fit on the scale.

Was that intentional? You just opened up a whole world of Uranus-related humour.

No wonder they pronounce it Ur-a-nus in the US. Spoilsports.

[Astro_Baby]

Damn ! Beaten to it - anyway they probably left Uranus off as its roughly the same size as Neptune. Saturns close to the same size as Jupiter but lets face it everyone wants to see Saturn.

If you like that video you may like this one which is a Voyager animation from NASA showing the little p[robe whole journey. Its a teensy bit dated but wonderful to watch.

[arad85]

Which one is that astro_baby No linky in the posty..

[tryme]

With the video what are the planets that I have never heard of before :| ?

[tryme]

Stars that we see in the night sky could support planets is this true? I'm getting confused because people say when you see a star with the naked eye it has already died

[arad85]

Stars that we see in the night sky could support planets is this true?

Yes could support...

I'm getting confused because people say when you see a star with the naked eye it has already died

Err... never heard that one before....

[crovax]

They probably simply want to say that the stars are very very far away from us. Since light travels with fixed "speed of light" you see the picture of the past. So when you're looking at some star cluster 25000 light years away, you see the light that started its way to you 25000 years away and now has finally reached Earth. May be 10000 years later (which is 15000 years back) this cluster had already been consumed by some black hole but you will know that such an event took place only in 10000 years.

However the statement that those stars are already dead is false. A star like Sun can maintin its current shape for around 10 billion years. Here's another good link on what happens with stars and how long that takes

Stellar evolution - Wikipedia, the free encyclopedia

[tryme]

This is to much for my brain to take! I don't understand how stars can be so close but the sun is the only star of it's kind if you know what I mean? If the sun is a star why aren't there any other "suns" near it and why do the stars we see in the night sky look so close together?

[Astro_Baby]

Heres the video link - whoops forgot to post it.

[Astro_Baby]

Tryme - I'll try and explain and make it easy on your head. Expert astro folk - yea I am taking a few liberties with terms and specifics....

The solar system comporises our Sun, which is a star itself, at the centre. Around it are the 9 planets of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, Uranus and Pluto. These orbit the sun at various distances. There are the inner planets of Mercury, Venus and Earth which are all essentially rocky in nature and the outer planets of Jupiter, Saturn, Neptune and Uranus which are 'gas giants' ie their size is made up from what is basically a huge ball of gas. Pluto is an outer planet but is mostly likley either a lump of rock or ice.

Thats the solar system and at its furthest point, if you were stood on Pluto for instance. Our sun would look like just a bright star. Its so big from one end of it to the other that light takes 15 hours to cross it. If you were stood on Pluto and and had a mobile phone to call earth with when you started talking it would take 15 hours before your words were heard on earth.

So thats our solar system.

Out there beyond the solar system is the galaxy. Our ones called 'The Milky Way' in the galaxy there are around 100 stars. The nearest ones are several light years away. How far away is that ? Well its a big distance. If the earth was the size of a pea then the nearest one would be 14,000 miles away.

Now the galaxy is kind of like the solar system. It has a centre to it and everything - all the stars in it including ours goes round and round the centre. The Galay is about 100,000 light years across so its HUGE. To put it into scale. If the earth were the size of a pea the Galaxy would be around 400,000 miles across. Imagine being even smaller than an ant and having to take a trek of 400,000 miles.

Now because the galaxy is so big light takes ages to get across it. Light travels very fast - but even light takes many years. The distances are so big we refer to them as light years. Thats the distance light covers in a year. Even the nearest stuff in the Galaxy to us is many years away. Because light takes so long to get here anything we see is really how it was 10, 15, 20 or hundreds of years ago.

When you look at a distant star you are seeing light that started its journey to us many years ago. Maybe thousands.

Outside the Galaxy there is the Universe and in the Universe there are millions of other Galaxies - so you can see that although the Solar system seems big to us against the Galaxy it is tiny.

Now each of those stars in our own Galaxy (which has a 100 billion stars in it) could support planets around it and so could any stars in other Galaxies but because the distances are so immense we have trouble seeing them.

Its as if you were standing in your garden and trying to read the a book thats in an aircraft flying overhead. There are some tricks that can be used that allow us to see that some stars near us actually do have planets. But we cant know if theres life there. EVen if aliens were living there their messages would take thousands of years to reach us.

The video I loaded shows Earth and some of the planets of our own SOlar Syatem compared to stars liuke our own sun and some of the bigger stars in our galaxy - you might say its comparing the biggest kids on the block.

Hope that helps you understand a bit better.

[arad85]

Our ones called 'The Milky Way' in the galaxy there are around 100 billion stars.

You missed out a very important magnitude in your text A_B

BTW, a billion is 1000000000 or one thousand million - we are talking VERY large numbers here...

[tryme]

Wow that is the best reply I have ever had on a forum .Thank you so much!

[Astro_Baby]

Well spotted arad - yes - 100billion stars (blushes - silly typing mistake) - thats lots - the numbers are huge Tryme - even people who do this all the time sometimes struggle with the massive numbers - they kind of make anything look small.

They are so truly huge in astronomy its very hard to get any perspective. Take comfoprt from the fact the univers has to be on that kind of scale for life to have a chance. If it were smaller then things would happen faster - stars would come and go too quickly for life ever to get a foothold.