• Question: Why do we see the stars at night?

    Asked by WiggleWaggleWorm to Maggie, Ry, Scott on 15 Nov 2017.
    • Photo: Ry Cutter

      Ry Cutter answered on 15 Nov 2017:

      The main reason we can’t see stars in the day time is because of the sun! They’re there all the time, the sun just obscures them. It’s so bright we can’t see the star light! It’s the same effect with street lights, we call it light pollution. Our eyes our like cameras, they calibrate to the brightest thing. Which means the really faint stars just aren’t bright enough compared to the lights on Earth. This is one of the reasons we have to build telescopes so far away from civilisation, too much light!
      If we as humans go to a place where there is no artificial light, we can see to an apparent magnitude of 6.5 , which is about 1,000,000,000,000,000,000,000 times fainter than our sun. This means, on Earth we can see about 90,000 stars.
      The telescope I’m using can see down to an apparent magnitude of 21. That’s 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 (47 zeroes!) times fainter than the sun. We can see lots of stars with that.
      I hope that answered your question 😀
      Ryan

    • Photo: Maggie Lieu

      Maggie Lieu answered on 15 Nov 2017:

      We see stars at night because stars are burning balls of hydrogen just like our Sun but we can’t see them in the day because our Sun is too bright.

      Alpha centuri is the closest star to us but its so far away that it takes 4.3 years for the light to reach us! Some stars are so far away that it could take 100’s of billions of years to reach us. So by the time we see it, the star might already be dead! So next time you look into sky, know that many of the stars aren’t even there anymore because its taken so long for the light to reach us!

    • Photo: Scott Melville

      Scott Melville answered on 16 Nov 2017:

      Good question! The answer, like the others said, is that our eyes are just not quite strong enough to make out the very faint stars during the day (because the Sun is so bright). They’re still all there though (don’t worry 🙂 ), because whenever there’s a total eclipse then you can see all of the stars (even though it’s day time).That’s really cool!

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