TechnicalResearch

Why does this place get the most Total Solar Eclipses?

Veritasium

A deep dive into total solar eclipses featuring NASA observations during Spain's 2026 eclipse, explaining why the Northern Hemisphere experiences more total eclipses, the physics of eclipse phenomena like shadow bands and Bailey's beads, and the historical discovery of helium through eclipse observations.

Summary

The video follows creators visiting Spain to observe a total solar eclipse while collaborating with NASA scientists and balloon launch teams. The hosts investigate several eclipse mysteries: why the Northern Hemisphere receives approximately 15% more total solar eclipses than the Southern Hemisphere, why the sun appears white during totality versus yellowish during partial phases, and what causes shadow bands on the ground.

The explanation for hemispheric differences stems from orbital mechanics: Earth's elliptical orbit makes the sun appear 7% smaller in July than January, increasing total eclipse probability. July coincides with Northern Hemisphere summer when that region tilts toward the sun. The Southern Hemisphere will conversely receive more total eclipses in approximately 9,500 years due to Earth's axial precession.

The video explains eclipse frequency patterns through eclipse seasons—34-day windows occurring roughly every six months when the moon's orbital nodes align with the Earth-Sun plane. Since new moons occur every 29.5 days, at least one always falls within each eclipse season, guaranteeing minimum two solar eclipses annually, with up to five possible when accounting for partial eclipses and seasonal drift.

The sun appears white during totality simply because solar filters used during partial phases create the yellowish appearance; without filters during totality, observers see the sun's actual white light. Shadow band mystery remains partially unsolved, though the leading theory involves atmospheric refraction of light through varying temperature and density layers, potentially amplified by the moon's topography creating multiple point sources of light interference.

Historically, the 1868 total eclipse enabled French astronomer Jules Janssen to discover helium through spectral analysis of solar prominences, later confirmed by Norman Lockyer. A similar method led to the false discovery of 'coronium,' later identified as iron stripped of 13 electrons by extreme heat. NASA's modern eclipse missions use balloons and aircraft to study the sun's corona with greater stability than ground observations allow.

Key Insights

  • The Northern Hemisphere receives about 15% more total solar eclipses than the Southern Hemisphere because Earth's elliptical orbit makes the sun 7% smaller in July, when the Northern Hemisphere is tilted toward the sun during summer
  • Eclipse seasons occur every six months when the moon's orbital nodes align with the Earth-Sun plane, creating 34-day windows where solar eclipses become possible, and since new moons happen every 29.5 days, at least one new moon must fall within each season, guaranteeing minimum two solar eclipses per year
  • The sun appears yellowish during partial eclipse phases due to the common reddish-orange filters used in photography, but during totality it appears white because it is bright enough to observe directly without filters, revealing the sun's actual white light
  • Shadow bands form due to atmospheric refraction as narrow beams of light pass through multiple layers of air with varying temperatures and densities, similar to the effect that makes starlight twinkle, with additional amplification from the moon's topography creating multiple point sources of light interference
  • The 1868 total solar eclipse allowed French astronomer Jules Janssen to discover helium by analyzing the spectral lines of solar prominences, while a similar method led to the false discovery of 'coronium,' later revealed to be iron with 13 electrons stripped away by extreme solar heat

Topics

Total solar eclipse frequency and hemispheric distributionOrbital mechanics and eclipse periodicityEclipse season and new moon timingLight behavior and pinhole camera effectsShadow bands and atmospheric refractionHistorical eclipse discoveries (helium and coronium)NASA eclipse observation methodsCorona and prominences observation

Transcript

[0:00] In just a couple of seconds Spain is about to get its first total solar eclipse in over 100 years. And we're here with NASA to film it from space. But we almost didn't do this video because it turns out there are a great couple videos on solar eclipses on YouTube, and we just thought we couldn't add anything. But then we started looking. [laughs] Oh my God, that's insane! And it turns out... Oh, I can't, I just gotta go watch this. That's insane. So, Henry, Emilia and I still had [0:31] some unanswered questions like, why is the Northern Hemisphere getting more total eclipses than the southern hemisphere? Why does the sun suddenly turn white only…

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