{"id":796455,"date":"2025-06-04T06:15:03","date_gmt":"2025-06-04T11:15:03","guid":{"rendered":"http:\/\/spaceweekly.com\/?p=796455"},"modified":"2025-06-04T06:15:03","modified_gmt":"2025-06-04T11:15:03","slug":"why-do-stars-twinkle-but-planets-do-not","status":"publish","type":"post","link":"https:\/\/spaceweekly.com\/?p=796455","title":{"rendered":"Why do stars twinkle, but planets do not?"},"content":{"rendered":"


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The more atmosphere you are peering through, the more stars (or planets) appear to twinkle. Read below why stars twinkle, but planets do not. Chart by AstroBob. Used with permission.<\/figcaption><\/figure>\n

Stars twinkle, while planets (usually) shine steadily. Why? <\/h3>\n

Stars twinkle because they\u2019re so far away from Earth that, even through large telescopes, they appear only as pinpoints. And it\u2019s easy for Earth\u2019s atmosphere to disturb the pinpoint light of a star. As a star\u2019s light pierces our atmosphere, it\u2019s refracted \u2013 causing it to change direction slightly \u2013 by the various temperature and density layers in Earth\u2019s atmosphere. You might think of it as the light traveling a zig-zag path to our eyes, instead of the straight path the light would travel if Earth didn\u2019t have an atmosphere. <\/p>\n

Astronomers use the term \u201cscintillation\u201d to describe the twinkling of stars. <\/p>\n

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The twinkling of the stars is called scintillation. Stars are so far away, that they are actually just points of light pic.twitter.com\/xcnIKKhYZE<\/a><\/p>\n

\u2014 Space Explorer Mike ?? (@MichaelGalanin) September 8, 2017<\/a><\/p>\n<\/blockquote>\n

On the other hand, planets are a more steady light<\/h3>\n

Planets shine more steadily because they\u2019re closer to Earth and so appear not<\/em> as pinpoints, but as tiny disks in our sky. You can see planets as disks if you looked through a telescope, while stars remain pinpoints. That\u2019s because Earth\u2019s atmosphere refracts the light from these little disks as it travels toward our eyes. But \u2013 while the light from one edge of a planet\u2019s disk might \u201czig\u201d one way \u2013 light from the opposite edge of the disk might be \u201czagging\u201d in an opposite way. The zigs and zags of light from a planetary disk cancel each other out, and that\u2019s why planets appear to shine steadily. <\/p>\n

You might see planets twinkling if you spot them low in the sky. That\u2019s because, in the direction of any horizon, you\u2019re looking through more atmosphere than when you look overhead. <\/p>\n

If you could see stars and planets from outer space, both would shine steadily. There\u2019d be no atmosphere to disturb the steady streaming of their light. <\/p>\n

Can you figure out which objects are stars and which are planets just by looking for the twinklers vs the non-twinklers? Experienced observers often can, but, at first, if you can recognize a planet in some other way, you might notice the steadiness of its light by contrasting it to a nearby star. <\/p>\n