6
$\begingroup$

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:

  1. 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?

  2. 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)

  3. 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.

|improve this question
$\endgroup$
  • 3
    $\begingroup$ 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. $\endgroup$ – barrycarter Sep 26 '15 at 22:47
  • 2
    $\begingroup$ 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. $\endgroup$ – James K Sep 27 '15 at 10:49
  • 2
    $\begingroup$ 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. $\endgroup$ – Peter U Sep 27 '15 at 20:18
  • 1
    $\begingroup$ 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. $\endgroup$ – Florin Andrei Sep 28 '15 at 18:17
  • 1
    $\begingroup$ 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. $\endgroup$ – userLTK May 16 '17 at 18:46
10
$\begingroup$

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.

|improve this answer
$\endgroup$
  • $\begingroup$ 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 :( $\endgroup$ – rajuGT Oct 8 '15 at 21:01
  • 2
    $\begingroup$ @rajuGT: Find a place far from the city lights. $\endgroup$ – Keith Thompson Oct 8 '15 at 21:39
  • $\begingroup$ 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. $\endgroup$ – Wayfaring Stranger May 25 '18 at 15:27
4
$\begingroup$

Is it because:

  1. Stars are dead?
  2. Current position of the earth in galaxy?
  3. Is it because of the city light/ pollution?

It's not #1 or #2. It's #3, plus other factors.

  1. Light pollution.
    Anyone who lives in or near a large city (that probably describes most of the the stackexchange network members) won't be able to see as many stars as someone who lives a hundred kilometers away from that city. Light pollution is a growing problem to astronomical observatories, even those very far removed from cities.

  2. Loss of visual acuity.
    If you're an adult, your visual acuity isn't as good as it was when you were a child. Visual acuity peaks between 8 and 15 years of age, depending on who you read. After 15, it's all downhill.

  3. Different levels of humidity, particulates, and air pollution.
    You will see fewer stars than nominal if you live in an area with high humidity, high levels of particulates, or high levels of air pollution. If you made such a change in locale recently, you will remember seeing a lot more stars than you can see now.

|improve this answer
$\endgroup$
3
$\begingroup$

If you've moved to an area with major aircraft traffic, you may be seeing fewer stars due to cirrus cloud formation. Such clouds are often subtle enough not to be visible as clouds but still block out starlight. For example: Forecasting Andean rainfall and crop yield from the influence of El Niño on Pleiades visibility

We find that poor visibility of the Pleiades in June—caused by an increase in subvisual high cirrus clouds—is indicative of an El Niño year, which is usually linked to reduced rainfall during the growing season several months later.

From the above, climate is obviously also a variable in star visibility.

Added:

Oh yes, aging is also a factor. The eyes opacify with age:

The normal aging processes in the eye mean that the retina of a 60 year old person recieves only about 30% of the amount of light seen by a person half that age.

|improve this answer
$\endgroup$

protected by Mike G Jun 12 at 4:58

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.