Will humans cease to exist eventually?

Humans will be extinct sooner than you think,,and long before the sun is any issue.
Yea, about 4 billion years from now, our sun will go red giant and totally crisper earth, even Jupiter will get flamed.

There is no doubt that our Sun will eventually go through the motions of Red Giant and White Dwarf respectively
None of which bode well for Earth itself which would probably end up a lump of ash
The Sun is around Half way through its lifetime at 4.5 Billion
 Surely Man can find a way to settle all our differences and realise we are all Humans and our only home is little Planet Earth
And strive to survive
Along with that will more than likely go our Technology
OK, the Farthest a Human has Got is the Moon
And the Voyagers are doing their best to beat all distance records
But we are getting there
Especially in the Higher and Faster department
 We have got a long way to go and who knows what could happen ?
Technology has come a long way since 1900

Your teacher is right.  The sun is a star & eventually it will burn out.

Yes, the sun will eventually expand into a red giant and bake the earth to a blackened cinder - killing ALL life.
That will not happen for a billion+ years, however.

In the meantime, I believe that humans will die out as a species much sooner than that.

The sun is predicted to become a red giant 4.5 billion years from now, thats plenty of time for humans to find a new home

Yes, the sun will become a red giant and swallow the earth. But this will happen in 4 billion years.

Humans will be extinct long before that. Most species last only a few hundred million years. Human have only been here for about 2 or 3 million years.

In billions of years the Sun will go nova, engulfing the Earth, then collapse into a cold dark rock. If there's life on Earth at that time, that will kill it.

As for humans, we've only been in our current form for 10's of thousands of years, with similar ancestors going back maybe 100,000 years. It's pretty unlikely humans, as we know them, will be here in 1 million years. Either we'll die out, or our descendants will be a different species. And maybe they won't be limited to Earth.

Your science teacher is correct but by this time humans will probably be living somewhere else in the universe.

Your science teacher sucks apparently (didnt teach you anything).
Our sun has another 4 billion years of life left. Plenty of time for
an intelligent race (if one evolves, from us unworthy lowlife scabby monkies) to relocate.

We accept it as true.

Long before the Sun goes out, it will get hotter and larger and cook the Earth.

It will be much more than thousands of years or millions of years.  Maybe a thousand million years.

Then some billions of years later, the Earth will cease to exist.

Read:
https://en.wikipedia.org/wiki/Future_of_Earth

Everything will die eventually, even the universe itself.  The reason is the second law of thermodynamics.

The vast majority of species that have ever lived on Earth went extinct. Why do you imagine that humans will be any different?

And it has nothing to do with the sun. Most extinctions are caused by factors such as resource exhaustion, overpopulation, and failing to adapt to changed environment. The timeframe we are looking at is measured in decades or centuries, not billions of years.

Yes that's true, and as for humans we could go extinct any day now.

Not exactly true.   What will happen.   In About 4.5 BILLION years  (not Million) our sun will turn into a RED GIANT Star (Not go out).   When the Sun runs out of Hydrogen Gas it will start fusing Helium Gas and EXPAND into a RED Giant.  It will Expand out to the orbit of Mars and completely destroy the inner planets.  Mercury, Venus and Earth, Maybe even Mars.
Ask your Science Teacher about our Sun and it's RED Giant stage.

The sun will broil the Earth dry in about a billion years. It will go out but that will take a hundred billion years.

Correct.  Stars don't have an infinite amount of fuel and eventually they run out.  It is predicted that in about 5 billion years, the Sun will swell up into a red giant because of being unable to shine by hydrogen fusion any more, and incinerate the Earth.  But the Sun will have been getting steadily hotter before that and it will probably be too hot for life before the Sun gets to the red giant stage.

We probably have 3-4 billion years, but that's a long time.  It's about as long as the Earth has already existed.

After the red giant stage, the Sun will shrink down to become a white dwarf and then slowly die out.  It's just as well the Sun is a very average-sized yellow dwarf - if it was much bigger, it'd run out of fuel quicker and explode.  But then life on Earth wouldn't have had time to evolve in the first place.

You've gotten the factual answers. The other answer is that it's nothing to lose sleep over.

Yes, but the way we are treating the planet it won't even take centuries

that is true, but it is many millions of years away, and humanity will be long gone at that point, either died out due to other reasons, or moved to other suns. 

One can only hope.

When the ocean currents are no more, all life will become extinct .

Yes, indeed. Time doesn't stop and stars have a life cycle. Our star/sun will eventually expand into the red giant stage and burn the earth to a cinder. But that won't occur for many millions of years. We have plenty of time to mess things up in the meantime.

Never believe science teachers. They are nothings but failed scientists who couldn't make it on the university level. Just kidding....it is true according to science.  All stars burn out. But maybe people will have evolved to a more spiritual form of existence in another galaxy, or plane. 

yes it is true, but war will probably destroy our planet first.

Certainly nothing lasts forever, the Sun's "lifetime" has little to do with it, biology does.  Modern humans did not exist even two million years ago, so it stands to reason that what we call humans will not exist in a few million years one way or another, we will be extinct or have evolved into some other kind of being.  Ten or twenty million years is nothing to the Sun.

If it will take a million years for the sun to disappear there is enough time for someone to escape the Milky way galaxy.

As long as Trump is president, it'll be sooner rather than later. 

A couple of things...
First, yes - it's true... our sun has a limited lifespan.  And, so does Earth. 

The sun is slowly getting brighter, as it burns through it's fuel - turning hydrogen into helium.  In about a billion to a billion and a half years, the sun's output will be so great that life on Earth will no longer be possible. 

About 3 billion years after that happens, our sun will begin to die... first, it'll go through a 'red giant' phase, in which it will likely consume Mercury, Venus, and eventually the Earth, then it will finish out it's life as a small white dwarf star, about the size of the Earth, slowly cooling over billions of years. 

Humans will be replaced by robots who will be better for this planet.

sure, if we haven't made ourselves extinct long before then

Yes some day it will happen.

The source URL gives the current ideas of the timeline of the far future.

My suspicion is that humanity will, through genetic manipulation and computer modeling, gradually take over the management of our own evolution, eventually resulting in our designating our own species as obsolete, with probably numerous human-like species (transhuman) replacing Homo Sapiens.

Humans will be all dead LONG before that.

Yes, they're called DEMOCRATS and hopefully cease to exist  sooner than a million years....Could be next NOVEMBER!

In the year 2525
If man is still alive
If woman can survive
They may find

In the year 3535
Ain't gonna need to tell the truth, tell no lie
Everything you think, do and say
Is in the pill you took today

In the year 4545
You ain't gonna need your teeth, won't need your eyes
You won't find a thing to chew
Nobody's gonna look at you

In the year 5555
Your arms hangin' limp at your sides
Your legs got nothin' to do
Some machine's doin' that for you

In the year 6565
You won't need no husband, won't need no wife
You'll pick your son, pick your daughter too
From the bottom of a long glass tube

In the year 7510
If God's a-coming, He oughta make it by then
Maybe He'll look around Himself and say
Guess it's time for the judgment day

In the year 8510
God is gonna shake His mighty head
He'll either say I'm pleased where man has been
Or tear it down, and start again

In the year 9595
I'm kinda wonderin' if man is gonna be alive
He's taken everything this old earth can give
And he ain't put back nothing

Now it's been ten thousand years
Man has cried a billion tears
For what, he never knew
Now man's reign is through!

It's all theory but there is proof

The physical Universe was constructed by our Creators.It was quite a work of art. However in  the Holy Bible it states that there will be a New Heaven and a New Earth.

If republicans keep getting their way then yes, most certainly. As inflation causes prices to go up, republicans are fighting tooth and nail with every pounce of strength they have 24 hours a day to make sure that no employee in America ever gets a pay raise ever. If they get their way then eventually no one will be able to afford food, etc. and, thus...the end.

Yes, this is true, but it will take billions of years for that to happen. The species homo sapiens will go extinct or evolve and no linger be homo sapiens long before that happens.