Less stars in the night, compared to 15-20 years back
I am not sure if my question is true or not. But this is what I observe regularly. When I was young and when I look at the sky, there were too many many stars were there. But now, from few months I'm observing the sky (by eyes, not any telescope), I see very few stars. Perhaps, countable.
Is it because:
Stars are dead? (Not all) As I read somewhere, by the time you see the star, it would have been dead. Because, the light would've traveled so many years to reach earth. By the time, star would have completed 'X' light years and it is dead by now?
Current position of the earth in galaxy: As I read, the earth will not always traverse in the same path around the sun. So the current view from the earth to the sky, may not have any star? (This is my guess/imagination, I'm not sure)
Is it because of the city light/ pollution?
PS: Please be easy. May be the question is broad or simple, just want to know the brief answer and if its complete explanatory, I'm happy for that.
Another reason is the falliablity of human memory. I too "remember" sparkling skyscapes of my youth. But I also remember that cartoons were funnier and sweets tasted better. Human memory is a strange thing.
You have to get outside of the City to see them. I was fascinated with how many Stars were visible, down in the Caribbean, when I looked up in the night sky.
It's 99% light pollution, 1% loss of visual acuity due to age. Drive to a place at least 1 hour away from any cities, towns, and industrial sites, and the sky will be full of stars again. I went to Death Valley a few months ago, and the sky at night was dazzling.
Just to add, if you could turn off the Milky way, including the solar-system and turn off the light pollution so you could only see other galaxies, which this question is about, you'd be surprised how dark the night sky would be. Galaxies are very far away and not that bright to our eyes. I suspect a pretty big part of the reason for that is dust blocking the light. For the more distant galaxies, Red shift is a factor.
@userLTK -- Only galaxies which happen to lie close to the Milky Way's disk (the Galactic "equator") are significantly blocked by dust in our galaxy. Most galaxies are faint simply because they're far away.
@PeterErwin Please edit the last sentence of your comment so it reads; *Most galaxies are faint simply because they're far, far away.*
I live in the country, am only in my 40's and the night sky still looks naked to my eyes. It has for most of my adult life. I've been wondering for years if we were losing stars. I remember big bright stars filling up the night sky and that's just not what I'm seeing anymore.
@ElizabethRamey Ability to perceive dim objects worsens with age, so it may be that you truly can see fewer stars than when you were younger and not because they are missing. On the other hand, our memories are also fallible. When you were younger the stars were more novel, so your brain perceived this as a vast multitude, whereas now they are usual and your brain perceives them as relatively fewer.
In my own case, if I see fewer stars than I did when I was younger, it's partly because my eyes have deteriorated with age. I don't know whether that applies to you.
The most likely explanation is increased light pollution. If you can manage to get to an area far enough away from city lights, on a cloudless and moonless night, you should see just as many stars as you did when you were younger.
Stars are dead?
No. All the stars you can see in the night sky are within a few hundred light-years of Earth. That means that you're seeing them as they were no more than a few hundred years ago. Most stars live for billions of years; the Sun, for example, is about 5 billion years old and is expected to live for another 5 billion or so years in essentially its current form. Some of the brighter stars have shorter lifespans (because they're larger and "burn" their nuclear fuel more quickly), but even they have lifespans of at least millions of years.
No naked-eye visible stars have "died" in the last several centuries. We do sometimes see stars explode (as novas or, more rarely, as supernovas), but I don't believe any of the stars that have done this were naked-eye visible before they exploded.
Current position of the earth in galaxy
No. The stars do move relative to each other, but not quickly enough for the motion to be visible over a human lifetime. Barnard's Star has the fastest proper motion of any star in the sky, but it only moves at about 10 arcseconds per year; it would take it nearly 2 centuries to move the width of a full Moon. And Barnard's star isn't even naked-eye visible. The stars you see in the night sky are in very nearly the same apparent positions as they were thousands of years ago.
Nope, my eyes are good. I'm still 24:) Thanks for the answer. But its really sad, I'm not able to see the sky full of stars :(
@rajuGT: Find a place far from the city lights.
Around here we seem to have developed a constant thin haze of high level cirrus clouds in the past couple decades. Sky used to be blue, now it's whitish blue. At night, that dims the stars. Lots of Global warming arguments about this widespread phenomena, but I'll just skip them in this comment.
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barrycarter 7 years ago
It's #3, but the number of visible stars has always been countable (if you exclude the shimmering ribbon that is the Milky Way). There are about 2000 of them give or take a few.