00:00when you look at the stars in the night sky they appear to twinkle have you ever wondered why
00:11the twinkling effect is caused by the uneven nature of the Earth's atmosphere closer to the
00:22ground the heating and cooling of the air causes pockets of air with different densities and shapes
00:28to form because the stars are so very far away their light rays are essentially parallel to each
00:36other when they first enter the upper atmosphere however when these light rays hit the different
00:44air pockets they are bent in different directions these pockets and layers of air move around this
00:55means that a light ray that arrives on the Earth's surface at one point at one particular time may
01:03not arrive at exactly the same point in the next second or even the next fraction of a second as a
01:12result of this the image of the star seems to shift around a little near the ground the light that
01:19reaches us from a particular star also seems to wobble and change in brightness this causes
01:26the twinkle objects that are closer to us such as the moon and the planets appear much larger than
01:35the stars and we receive more light from them they appear more like bright discs and the twinkling is
01:43nowhere near as obvious when we look at them astronomers call the twinkling atmospheric distortion and it
01:51causes the images of stars that they see in their telescopes to be blurry one way of limiting this
01:59atmospheric distortion is to build telescopes higher up in the atmosphere where the thinner air causes
02:06less bending of light rays from stars this is why many observatories are built on the tops of mountains
02:15and even better way is to send telescopes out of the atmosphere altogether space telescopes like the
02:24Hubble get incredibly clear images because they see the light from stars without distortion up in space there is no
02:35twinkle twinkle twinkle little star
