Why does this place get the most Total Solar Eclipses?
Veritasium
Chasing an eclipse in Spain 0:00
You join a team traveling to Burgos, Spain, to film a total solar eclipse from the ground and from space, working alongside NASA and other science groups launching balloons to the edge of the atmosphere. The trip starts with a handful of open questions, including why the Northern Hemisphere sees more total eclipses than the Southern Hemisphere, why the sun turns white only during totality, and what actually causes the strange shadow bands sometimes seen on the ground.
Why the north gets more eclipses 1:30
At any single spot on Earth, a total eclipse repeats roughly every 300 years, though patterns make some places luckier than others. Mapping every total eclipse from 2000 BCE to 3000 CE shows the Northern Hemisphere getting about 15 percent more than the south. This comes down to the moon's elliptical orbit, which changes its apparent size by up to 30 percent, combined with Earth's own elliptical path around the sun, which makes the sun appear about 7 percent smaller in July than in January, a time that lines up with Northern Hemisphere summer. The Southern Hemisphere instead gets more annular eclipses, where the moon looks slightly smaller than the sun and leaves a ring of light, since its summer coincides with the sun looking closer and bigger. Over about 9500 years, the slow drift of Earth's axis and orbit will flip this balance entirely.
Why eclipses cluster in seasons 3:33
Across 5000 years of data, no year passes without at least one solar eclipse, and some years get as many as five. The moon's orbit tilts about five degrees from the Earth-sun plane, so most months it passes too high or low to cast a shadow. Twice a year, though, the moon's orbit crosses that plane at points called nodes, opening a 34 day eclipse season. Since a new moon happens every 29.5 days, one is guaranteed to fall inside each season, guaranteeing at least two eclipses a year, and often more once partial eclipses near the edges of the season are counted, with the season itself drifting enough to occasionally produce five in one year. A related pattern is that every solar eclipse is paired with a lunar eclipse about two weeks before or after it, since that's when Earth sits directly between the sun and moon.
Why totality looks white 6:03
Timelapse videos of eclipses often show a yellowish tint fading into white at totality. That color comes from the filters needed to safely photograph the sun beforehand, not from any real change in the sun's light. During totality the light is dim enough to view directly, so you see the sun's true white color rather than the reddish tint of a filter.
Balloons and jets chasing shadow 7:02
A NASA funded lab from Bozeman, Montana is part of the Nationwide Eclipse Ballooning Project, launching engineering balloons in Spain and radiosondes in Iceland to study the eclipse from high altitude, using improvised weights like water bottles filled with rocks. Meanwhile another NASA team is chasing totality in a 70 year old Cold War era jet. In 1973 the Concorde flew at Mach 2 and stayed inside totality for 74 minutes, far longer than the two minutes and 18 seconds possible from the ground, while the newer jet, moving at 460 miles per hour, can only manage about three minutes. The point isn't just extra time in the shadow, since a jet is far steadier than a balloon and can carry more sensitive instruments for studying a very specific part of the sun.
Discovering an element in sunlight 10:00
That precise part of the sun once led to a real scientific breakthrough. During the total eclipse of August 18, 1868, French astronomer Jules Janssen studied the sun's prominences, the arcs of glowing gas visible at its edge, using a prism to split their light into wavelengths. One bright band matched no known element, and English astronomer Norman Lockyer soon named it helium after the Greek sun god Helios. The following year the same method applied to the sun's corona produced another mystery line, wrongly credited for 70 years to a supposed element called coronium, until 1939 revealed it was simply iron stripped of 13 electrons by extreme heat.
Shapes, shadows, and pinhole tricks 11:00
Cardboard cutouts of different shapes, held close to the ground, cast shadows matching their outline, but pulled further away those same shadows morph into crescents during an eclipse, because the gap is acting like a pinhole camera projecting the light source itself. This is why gaps between tree leaves scatter the ground with crescents during an eclipse, and why the crescents on the ground point opposite to the crescents in the sky, since light crossing through a small opening flips both top to bottom and left to right. Shadows also behave strangely as totality nears, appearing fuzzy in one direction and sharp when rotated 90 degrees, because the sun narrows into a sliver shape that acts like a point source in one direction only.
Shadow bands and the moment of totality 14:00
Right before totality, faint moving shadows called shadow bands or snake shadows sometimes ripple across the ground for just seconds, and their exact cause remains an open scientific question. The leading explanation is that narrow beams of light get bent while passing through layers of air at different temperatures, the same effect that makes stars twinkle, though this alone doesn't explain everything. An army engineer testing this idea from a hydrogen balloon during the 1905 eclipse in Burgos found shadow bands covering himself and his basket but not the white sheet meant to catch them, suggesting the moon's own uneven surface also plays a role by creating multiple overlapping light sources, similar to how several spotlights in a theater cast overlapping shadows.
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