• Question: Why can we only see some stars and not others in the sky at night? And why are some different colours then others?

    Asked by AdamW to Aisling, Colin, Laurence, Ned, Niamh on 3 Mar 2016.
    • Photo: Laurence O'Rourke

      Laurence O'Rourke answered on 3 Mar 2016:

      Great question – you might not believe it but space has a lot of dust which prevents us from seeing a lot of the stars/galaxies floating around up there. Also distance has a lot to do with it as regards how bright stars are and the light that arrives to the Earth. The colour gives a good idea of the temperature of the star – our own star (sun) is quite yellow, there are others which are red, for example, which are red giants. Lots of colours which is really nice to see in my opinion as looking at white all the time would be boring in a telescope.

    • Photo: Ned Dwyer

      Ned Dwyer answered on 3 Mar 2016:

      Even if the light from the star gets through the space dust it might not make it throuhj Earth’s atmosphere. Light from outside our planet gets absorbed and reflected by partcles and molecules in our atmosphere. The tempersture which a star burns at determins the colur we see. As Laurence says our star the sun burns at temperatures which emit yellow light.

    • Photo: Niamh Shaw

      Niamh Shaw answered on 4 Mar 2016:

      I think that Laurence and Ned have already answered the question really well. And some of those stars are also planets too, and the International Space Station orbiting our planet. I guess I would also say that our understanding of the Universe is limited only by the technology we use to see it and we are constantly learning about our place in space as a consequence.

      I wouldn’t worry about the stars you can’t see because we have space telescopes studying our Universe without having to worry about Earths atmosphere blocking & distorting the stars light that reaches our planet- pace telescopes like the Hubble Space Telescope, Kepler (and soon the James Webb telescope) as well as a telescope on the International Space Station.

      Whats really great about looking at the skies at night is knowing that all through history, different civilisations have been looking up to the stars looking for answers about our existence: Egyptians & Aztecs worshipped the sun, the Chinese were the first to name the stars, and the Babylonians invented Astrology. The first telescope was invented in 1608 and from then on, we began to see our place in the Universe differently. And we continue to learn as we look further and further out in to our dark night skies.

    • Photo: Colin Shirran

      Colin Shirran answered on 8 Mar 2016:

      I’m not sure I can add much more that the other engineers haven’t already said. The atmosphere really affects the amount of stars we can see with the naked eye. Check out the picture that Gaia has taken of all the stars in our galaxy. It’s a crazy amount and really shows you just how many stars we can’t actually see.

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