Why do the Stars Twinkle? World Space Week | Greg Foot | Head Squeeze

UPDATE: Here's the proper explanation for why planet's DON'T twinkle (thanks to TheHue's SciTech!) The stars are a loooong way away, whereas the moon & planets are close enough, that means stars have a much smaller apparent size. So planets appear as discs, stars are still points. The twinkling effect is averaged out over the large disc, but not the small points of light (stars).

Even HeadSqueezers aren't perfect -- thanks for keeping us on our toes!

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It's Space Week and Greg takes an astronomically scintillating look skyward to tell us why the stars twinkle.

Apparently the twinkling of the stars is known as astronomical scintillation and it's caused not by the stars themselves but by the Earth's atmosphere. In order to reach our eyes, the light from the stars must travel through constantly moving pockets of warm and cold air in our atmosphere. The light hits what are basically changes in density, so it is refracted and bent in random directions. Thus the stars twinkle romantically for us on Earth. Were you to observe them from the moon however they would not, as it has no atmosphere.

The reason why the moon and the planets do not twinkle, is they are that much closer to us. Some of the light rays from these bodies are refracted but when viewed together we can see them as a whole.

Thanks to Patanegn for posting the question here on YouTube. If you have a good one, post it in the comments section. And if you enjoyed this video give us a thumbs up, share us with your friends and subscribe for more heavenly wisdom from Greg Foot.

[BBCEarthScience]

Thanks guys! We love getting all your comments and how you all answer each other's questions. Happy Head Squeezing!

[BBCEarthScience]

You're right Jason, check the description for an update. Well spotted.

[louischapman]

although these videos are really simple, theyre some of my favourite science videos

[BBCEarthScience]

When Greg is explaining Why Planets Don't Twinkle he says the Stars are a loooong way away, whereas the moon & planets are close enough. That means, as @TheHue's_Sci_Tech outlines brilliantly, that "stars have a much smaller apparent size. Look through a decent telescope, planets appear as discs, stars are still points. The twinkling effect is averaged out over the large disc, but not the small points of light (stars).

[TheRedPython]

Hi Saeed, you are not wrong. The effect you describe is real, it's just we can't see it with our eyes as they are not sensitive enough. Twinkling stars are a different phenomenon caused by the varying refraction of the atmosphere. Refraction is also the reason rocks at a bottom of a pool seem to move as water ripples on the surface above them.

[TheDanPerkins]

The moon and planets are larger disks occupying a 'real amount' of our degrees of vision, stars are point lights. So we only get a very narrow stream of light from a star, so when it is refracted by star noticeably 'moves' and the colour changes from refraction effect 'all' of the light we see. Moon/Planets move by same amount, but it is mitigated by their larger image. More light points, flickering of colour is much less noticeable

[BBCEarthScience]

Bonus HeadSqueeze points to @larsdo1990 for pointing out a gap in the explanation, and for @TheHue's_Sci_Tech for answering it!

[Skip]

I'm glad you guys are pointing out the correct answer here, but why do you phrase it as if your original explanation was correct, and just needed a little more clarifying? It's alright to make mistakes, which you clearly did, as long as you own up to them, but the wording of your comment is still ambiguous, and could lead someone to continue to believe the video, which is objectively wrong.

Thank you so much for these videos, and keep up the great work!

[ThomasEdwardsYo]

Who ever edits these... You are awesome

[LeRuruche]

Thanks for clearing things up. I was confused

[HeidiH]

Thank you for this video! My 6 yr. old daughter is doing her science fair project on "why do stars twinkle?" Sometimes as a parent, you just don't REALLY know the answer to every question a child asks. (But our children think we do? lol!) This video really helped her to understand (and me too!)

[SMOshee]

I thinking the word we are looking for is astronomical scintillation... because of the atmosphere the light from the stars is distorted and appears to be at different places at different times (twinkling effect). Since light from the star is a point source, as you said, the distortion is grater; which is why it seems as thought the stars twinkle. Distorted light from the planets/sun is still roughly in the same area because of the larger light surface area of light and smaller distortion radius.

[mathardie]

Hi Greg. Love the videos. Quick question. How do we get our last name? Where does it come from?

[SMOshee]

Hi Greg! Like your videos. I feel the twinkling is because of inverse square law, which states that intensity of the light is inversely proportional to the square of the distance from the star so as we move away from the star, the light will get dimmer & dimmer until we reach a point when, because the light is quantized, we get just flashes of the light. As we move further the flashes don't lose brightness but the flashes are spaced further from each other i.e. twinkling. need more characters...

[miqdadalyeet]

Jason i think he is also talking about the fact that we will see light from the planets before the stars

[vidrata]

Awesome chanel Guys! Very informative and fun! Here is a question: Why most dogs dont like cats?

[RandomDanStuffses]

So these sub-atmospheric planets, are they invisible too? I've never seen any.
The fact is, that the planets DO 'twinkle' if you've ever actually looked through a telescope, but because they are bigger you can still usually make out the shape, but when the atmosphere is particularly turbulent, you lose surface detail.
Greg, I'm disappointed that you didn't notice this...

[eloszkaxD]

I've got a question for you. Why does radio wave travels at the speed of light?

[nonamedpleb]

Twinkle twinkle little stars nursery rhyme brought me here.

[TMIGT]

why is there no youtube feature for space week?