Why is the Night Sky Black and not Blue? | February 2 - February 8
Season 49 Episode 5 | 1mVideo has Closed Captions
Star Gazers STGZ550 February 2-8, 2026 “Why is the Night Sky Black and not Blue?”
Star Gazers STGZ550 February 2-8, 2026 “Why is the Night Sky Black and not Blue?”
Problems playing video? | Closed Captioning Feedback
Problems playing video? | Closed Captioning Feedback
Star Gazers is presented by your local public television station.
Funding provided by The Batchelor Foundation and The William J. & Tina Rosenberg Foundation
Why is the Night Sky Black and not Blue? | February 2 - February 8
Season 49 Episode 5 | 1mVideo has Closed Captions
Star Gazers STGZ550 February 2-8, 2026 “Why is the Night Sky Black and not Blue?”
Problems playing video? | Closed Captioning Feedback
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Star Gazers is available to stream on pbs.org and the free PBS App, available on iPhone, Apple TV, Android TV, Android smartphones, Amazon Fire TV, Amazon Fire Tablet, Roku, Samsung Smart TV, and Vizio.
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Learn Moreabout PBS online sponsorshipHEY THERE SKY-WATCHERS!
WHY IS THE# SKY BLACK AT NIGHT?
IT SEEMS A SILLY, BUT THIS QUESTION HAS HUGE IMPLICATIONS HIT THE DARKNESS AT TEN PM.
LOOK# NORTH.
THE TWO STARS ON THE END OF THE BIG DIPPER’S BOWL POINT# TO POLARIS - THE NORTH STAR.
LOOKING AT POLARIS THROUGH A TELESCOPE# WE CAN SEE IT’S SURROUNDED BY STARS!
HOW IS A SKY FILLED WITH BILLIONS OF SUNS# SO DARK?
THIS IDEA BROKE THE COMMONLY HELD BELIEF THAT THE UNIVERSE WAS STATIC.
INSTEAD# IT HAD A BEGINNING AND IS STILL EXPANDING!
EXPANSION MEANS STARS DRIFT AWAY FROM# EACH OTHER OVER BILLIONS OF YEARS.
SO, LIGHT BETWEEN THEM STRETCHES# TURNING IT REDDER - CALLED REDSHIFT.
STARS LIKE POLARIS HELPED PROVE THIS REDSHIFT# IS TRUE BECAUSE THEY DIM AT REGULAR INTERVALS!
THEY’RE CALLED CEPHID VARIABLES, AFTER FIRST# KNOWN ONE, DELTA CEPHEI - FOUND HERE IN CEPHEUS!
AS LIGHT SHIFTS RED, IT GETS DIMMER AND EVENTUALLY# CAN’T BE SEEN, GIVING A GORGEOUS, BLACK SKY.
KEEP LOOKIN’ UP!
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Star Gazers is presented by your local public television station.
Funding provided by The Batchelor Foundation and The William J. & Tina Rosenberg Foundation