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why is the sun a star?

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#1 gasgiant

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Posted 13 June 2018 - 03:08 PM

This part confuses me. Are they saying the sun is actually a star as in stars I see in the night skies? Is the moon also a star? Could someone clarify? If the sun is a star, does that mean the stars I see at night are actually suns in another universe or what?


 

#2 Waddensky

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Posted 13 June 2018 - 03:21 PM

Yes, the Sun is a star, just like any other star you can see at night. The difference from our perspective is, that the Earth is a planet that orbits the Sun, so the Sun is much, much closer than the other stars and therefore seems brighter and larger. We now know that there are planets orbiting other stars as well, so in a sense they are 'Suns' from the perspective of their own planets. All stars are in the same universe, however.


 

#3 nicoledoula

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Posted 13 June 2018 - 03:43 PM

That's what they say gasgiant.  That this is happening: https://www.youtube....jHsq36_NTU&t=7s


 

#4 Sky Muse

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Posted 13 June 2018 - 03:47 PM

Sometimes a group of stars is called a group of suns.


 

#5 trurl

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Posted 13 June 2018 - 03:50 PM

That's what they say gasgiant.  That this is happening: https://www.youtube....jHsq36_NTU&t=7s

No to the video.

 

http://curious.astro...xy-intermediate


 

#6 bobzeq25

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Posted 13 June 2018 - 03:50 PM

Yes, the Sun is a star, while the Moon is not.

 

It's a ball of very hot hydrogen (plus some other things), that's heated and lit up from fusion reactions.  That's what a star is, generally.

 

The closest other star is 65,000 times farther away, which is what makes the stars you see different.  The edge of our universe  is many millions of times farther away.  The distances involved here are enormous.  We can write them down, but they're impossible for our mind to truly grasp.


Edited by bobzeq25, 13 June 2018 - 03:56 PM.

 

#7 koop12

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Posted 13 June 2018 - 04:19 PM

Yes, the Sun is a star, just like any other star you can see at night. The difference from our perspective is, that the Earth is a planet that orbits the Sun, so the Sun is much, much closer than the other stars and therefore seems brighter and larger. We now know that there are planets orbiting other stars as well, so in a sense they are 'Suns' from the perspective of their own planets. All stars are in the same universe, however.

Best explanation for the sun and the stars we see in the sky. 

 

Stars are categorized by size, temperature, color and stages of their life cycles. There are Red Dwarfs that emit so little light that they can't been seen with the naked eye in the sky. Ironically our closest neighbor is one such star, and it's very difficult to see without the aid of a telescope. There are other stars that simply don't emit light on a spectrum we can see. If our eyes could pick up these stars, our night sky would look incredible dense with red and brown dots swarming everywhere.

 

But yeah, stars the most important structures in the observable Universe. Most of what we observe in our telescopes are stars, binary stars, the death of stars, the birth of new stars, dense groups of stars, and islands of stars millions of light-years away. And of course when we see our planets, we are looking at the results of stars that exploded and left all the beautiful elements to form.


 

#8 macdonjh

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Posted 13 June 2018 - 05:15 PM

Yes, the Sun is a star, while the Moon is not.

 

It's a ball of very hot hydrogen (plus some other things), that's heated and lit up from fusion reactions.  That's what a star is, generally.

 

The closest other star is 65,000 times farther away, which is what makes the stars you see different.  The edge of our universe  is many millions of times farther away.  The distances involved here are enormous.  We can write them down, but they're impossible for our mind to truly grasp.

+1 A star is a mass of gas that contains enough material to sqeeze together under its own gravity until the pressure and temperature are high enough that nuclear fusion starts.  That creates enough energy and pressure to balance the squeezing force of gravity and the star becomes stable.  Stars contain mostly hydrogen, but as bobzeq25 says, other elements are also present in most stars.

 

The reason you see the Sun during the daytime is that's when the part of Earth you live on points toward the Sun.  At night, your part of Earth points away from the Sun, so you can't see it.  Think of it this way: If you face a lamp on a table, you can see it, when you turn around, you can't see the lamp anymore because it's behind you.  The reason you can see the other stars in space at night it because when you're on the side of the Earth that's facing away from the Sun, the sky is dark enough that you can see the other stars.  When your part of Earth is pointing toward the Sun, there is so much light in the sky from the Sun that the other stars can't be seen.  They are still there, though.

 

The moon is a satellite of the planet Earth.  It's made of rock, not hydrogen.  It does not glow by itself.  The reason it glows at night is because sunlight reflects off it and shines on Earth.  If you were to take the moon and put it in orbit around the Sun out by Pluto, it would be so dim it's likely on the Hubble telescope would be able to see it.

 

The stars you see in the sky are generally similar to the Sun: they all have nuclear fusion reactions going that generate heat, light and pressure.  The stars you can see with your eyes or thought a telescope are all part of this galaxy, the Milky Way, not some other universe.  Stars that are part of other galaxies within this universe are too far away to be seen individually by all but the biggest professional telescopes.  

 

As Waddensky says, astronomers have also proven there are planets that orbit other stars (or, if you prefer, suns) in our galaxy.  Some of those planets may also have moons.


 

#9 sg6

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Posted 13 June 2018 - 05:19 PM

Yes the sun is just another star, actually a fairly middle of the road star and of no special significance in terms of stars.

 

Stars are generally defined as being a gravitationally bound mass of mainly Hydrogen gas that generate and emit light/energy (radiation) owing to hydrogen fusion in the core. The general fusion process being Hydrogen -> Helium.

 

Later in the life of a star other fusion processes can/will occur as in Helium > Carbon. However after the Hydrogen to Helium stage the end is in sight for the star as in the processes after Hydrogen tend to be shorter lived.

 

Until recently it was "simply" a case that a star was defined as producing energy by the fusion process.

 

The "old" star catagorisation of O, B, A, F, G, K and M was used for many years - the Sun is a G type - recently there have been others introduced at the lower end. Strange there seems to be 2 options for the "new" catagories. Wikipedia give L, T and Y as a further 3 below M. Also it seems that the requirement of "fusion" has kind of gone also at the lower end. Some of the Y type stars are understood to be around 300K, which is more or less the same temperature as you and the rest of the people on CN are.

 

Personally I think the fusion requirement seems a good one.

 

Additionally as it appears that all stars have planets or planetary systems around them then equally we are just another planetary system orbiting a fairly common middle of the road star.


Edited by sg6, 13 June 2018 - 05:21 PM.

 

#10 bobzeq25

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Posted 13 June 2018 - 05:46 PM


 

The moon is a satellite of the planet Earth.  It's made of rock, not hydrogen.  It does not glow by itself.  The reason it glows at night is because sunlight reflects off it and shines on Earth.  If you were to take the moon and put it in orbit around the Sun out by Pluto, it would be so dim it's likely on the Hubble telescope would be able to see it.

I think you meant unlikely.  But no.  The Moon reflects about 1/4 as much light as Pluto, and is twice the size (based on area, not diameter).  So it would be half as bright, and extremely easy for the Hubble, which sees things many, many times dimmer than Pluto.

 

An amateur could see it in a medium largish telescope, and photograph it in a small one.


Edited by bobzeq25, 13 June 2018 - 05:51 PM.

 

#11 Adun

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Posted 13 June 2018 - 07:50 PM

This part confuses me. Are they saying the sun is actually a star as in stars I see in the night skies? Is the moon also a star? Could someone clarify? If the sun is a star, does that mean the stars I see at night are actually suns in another universe or what?

 

A simple way to think of it is this: Stars are actually Suns, they are just so very very far away they look like tiny dots from here.

They are in this universe, just very very far.


 

#12 havasman

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Posted 13 June 2018 - 08:22 PM

Nothing you will ever see through a telescope is in another universe.


 

#13 Pinbout

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Posted 13 June 2018 - 09:07 PM

Nothing you will ever see through a telescope is in another universe.

you'd have to peer thru a black hole for an alternate  universe...


 

#14 Pinbout

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Posted 13 June 2018 - 09:11 PM

That's what they say gasgiant.  That this is happening: https://www.youtube....jHsq36_NTU&t=7s

I always thought our plane was parallel to the milkway, just never thought it wasn't. but with the disc rotating over our head makes sense that we're not...

 

I like the scale of our solar system...get it solar...sun... its a sun cause smarter people tell me it is. ha ha ha...

 

https://www.youtube....h?v=9tzxz3zxU0I

 

 

 

I've heard Jupiter is almost big enough to go "flame on"

 

if it did we'd have a binary star solar system... but boy our butts would get hot


Edited by Pinbout, 13 June 2018 - 09:12 PM.

 

#15 csrlice12

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Posted 14 June 2018 - 01:01 AM

Because if it wasn't we would be a cold lifeless ball of rock....assuming Earth even formed.


 

#16 penguinx64

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Posted 14 June 2018 - 02:19 AM

Some stars are in Hollywood

Attached Thumbnails

  • Star.jpg

 

#17 SirLoyne

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Posted 15 June 2018 - 05:49 PM


I've heard Jupiter is almost big enough to go "flame on"

 

if it did we'd have a binary star solar system... but boy our butts would get hot

Jupiter would have to have 13x more mass than it has now just to become a Brown Dwarf, and 80x more mass to become equal to the smallest Red Dwarf.


 

#18 SirLoyne

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Posted 15 June 2018 - 06:01 PM

This part confuses me. Are they saying the sun is actually a star as in stars I see in the night skies? Is the moon also a star? Could someone clarify? If the sun is a star, does that mean the stars I see at night are actually suns in another universe or what?

All stars are suns and all suns are stars. The Sun just looks different because of how close we are to it. Not only are all of the stars you see at night in the same Universe, they're in the same galaxy, The Milky Way, which contains roughly 200 Billion (200,000,000,000) stars. The Milky Way itself is only 1 of 100 Billion (100,000,000,000) galaxies in the Universe.

 

Earth's Location In The Universe

https://www.dropbox....iverse.jpg?dl=0

 

Feeling small yet?


Edited by SirLoyne, 15 June 2018 - 06:04 PM.

 

#19 Dark Matters

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Posted 15 June 2018 - 09:36 PM

This part confuses me. Are they saying the sun is actually a star as in stars I see in the night skies? Is the moon also a star? Could someone clarify? If the sun is a star, does that mean the stars I see at night are actually suns in another universe or what?


 

#20 Greyhaven

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Posted 16 June 2018 - 08:53 AM

This part confuses me. Are they saying the sun is actually a star as in stars I see in the night skies? Is the moon also a star? Could someone clarify? If the sun is a star, does that mean the stars I see at night are actually suns in another universe or what?

Simply put: The Sun is a star all stars are suns. The capital (S) makes all the difference.

Grey


 

#21 Achernar

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Posted 16 June 2018 - 09:02 AM

The Sun is a star because:

 

It has more than 75 or 80 times the mass of Jupiter, the point where self-sustaining hydrogen fusion occurs. At the same time, it's not so massive it would explode when nuclear fusion starts or simply collapse directly into a black hole.

 

It generates its own internal energy, and does not shine by simply radiating heat left over from its formation. It is a continuous thermonuclear explosion whose outward push exactly counterbalances the inward pull of gravity. As a result, 4,000,000 tons of mass disappears every second and is converted into high energy gamma rays that heat the interior as they gradually are converted to light and heat.

 

The stars you see in the night sky are indeed in our Universe and not another, and most are a few tens or hundreds of light years away. We can only see a small region of the Milky Way in visible light due to obscuration, absorption and scattering of starlight from interstellar dust.

 

Taras


Edited by Achernar, 16 June 2018 - 09:10 AM.

 

#22 Ken Sturrock

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Posted 16 June 2018 - 11:09 AM

At this point, the Original Poster (who is not really a beginner to astronomy) has probably had his question answered as best as we are able.

 

Additional reading from an introductory text book in Astronomy, or perhaps, Set Theory may be in order.

 

Thanks to everyone for their input.


 


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