Twilight and the Rotating Earth @BobtheScienceGuy

Uploaded March 2022 | Updated September 2026, 3 weeks ago

This video takes a practical look at twilight and the rotating earth, focusing on the physics, the prediction, and what we should actually observe.

In this video we discuss the stages of twilight and their characteristics. We use Date and Time, the Astrolabe and Stellarium to visualize the twilight effects.

Twilight requires a rotating spherical earth. It is as simple as that. We discuss the cause of the three stages of twilight- Civil, Nautical and Astronomic Twilight in terms of the position of the sun.

Bob's Websites
Check them OUT:

Bob the Science Guy: youtube.com/user/drbob420

ResearchFlatMoon (the production channel):
youtube.com/c/ResearchFlatMoon

Slide Rules and Mathematics (STEM Education):
youtube.com/channel/UCEXa89aIdG222z8ADB0e7GA

Common Sense Science (Archive and Livestreams):
youtube.com/c/CommonSenseScience

Bob

Join our Discord Channel at discord.gg/QwcFct7DWc

Help the Channel by joining our channel as a member

Bob the Science Guy
Science You Can Test

Centrifugal Force Explained | Apparent Forces and Rotation

How 99% of the World’s Population Can Be in Sunlight at Once

Why Science Does Not Require Absolute Certainty

$Atmospheric Refraction: Why Light Bends Near the Horizon$

Entropy, Gravity and Why Atmospheric Pressure Has a Gradient

$First Light with the New Equipment This is the edited version of last nights telescope session, the raw footage has been moved to the channel members only section. The session was first light with the new StellarVue SV80 telescope and covered the Bode Cluster of Galaxies and some excellent shots of satellites. Live discussion on Discord during the session. Equipment: Main Camera ZWO 294 (thanks Wolfie6020) Telescope StellarVue SV 80 refractor (80x550mm) Mount Exos2 PMC8 with Ascom Control Software- APT, SharpCap, SkyTracker, PHD2, and Stellarium Bob the Science Guy is a YouTube Creator hosting a daily live stream and creating original content debunking conspiracies such as Flat Derp, Moon Landing Denial and Anti-Derp. Join our Discord Channel at https://discord.gg/CA2r9U378X Bob the Science Guy on YouTube: https://discord.gg/CA2r9U378X Bob the Science Guy on Twitch: https://www.twitch.tv/bobthescienceguy Common Sense Science on YouTube (astronomy and Science): https://www.youtube.com/channel/UCnTW4kCAmTt2qtXJ13kGxYA Support the Channel and help with the costs of the telescope and video Equipment: https://www.patreon.com/bobthescienceguy To make a direct donation for the telescope mount, click here: https://www.paypal.com/donate?hosted_button_id=P6THXXKV5UR9Q Cool Stuff from the Bob the Science Guy Store: https://teespring.com/stores/cool-mugs-and-stuff-from-bob Thank you for stopping by! Bob the Science Guy$

The Moon from Shamrock Banks Observatory

Can Undersea Cable Lengths Directly Test Earth’s Geometry?