Do stars appear larger when they are close to the horizon, like with the moon?

sequoianoir

YES. The effect is truly an {illusion;} the moon's size is no different wherever it appears in the sky - a constant half a degree across. Similarly, atmosphere does not play any tricks on your eyesight, indeed, if it were to have an effect it would make the moon appear smaller on the horizon not larger. Instead we need to delve into our own minds to find an explanation. Many scientists have done just that, and there are numerous different theories based on cognitive psychology through to neurophysiology.. One likely explanation is that the moon illusion works in the same way as another common illusion, first presented by Mario Ponzo in 1913. The railway line or Ponzo illusion shows two identical blocks that are placed on 'tracks' that converge in the 'distance'. Our brain figures that the block nearer to where the tracks converge must be further away. And if it is further away, it must also be bigger. This illusion may well make us see large moons on the horizon. When we look up at the sky, we think of it as the underside of a large dome. Curiously, people invariably describe the sky at the horizon as further away than the sky overhead. Because the rising moon is seen against a background that is perceived as more distant, our brains think that the moon is larger than when seen against the 'closer' overhead sky. It is not only the moon that is affected by the illusion - it works with the sun and constellations. Please do not look directly at the sun as you can permanently damage your eyes, but on the next clear night try watching the star patterns shrink as they rise higher in the sky. http://www.bbc.co.uk/science/scienceshack/backcat/experiments/mamoonillusion.shtml Dec 08 02, 4:40 PM

Gnomon

NO Stars are so far away that they never appear any bigger than single points. Dec 09 02, 9:22 AM

Nude Dude

Sorry Gnomon. Yes! The distances between the individual stars within a constellation appear to increase when the constellation is close to the horizon. This effect is particularly striking for the constellation of Orion in winter, and Cygnus in summer. Dec 09 02, 11:37 AM