Pilots can easily observe that Earth is a sphere, either by visual observation or from the aircraft’s flight instrument.
The level indicator is above the visible horizon. It is the dip of the horizon caused by the fact that Earth is a sphere. Earth’s horizon itself is visibly curving. The horizontal component of the velocity vector is often not the same as the plane’s direction due to the wind & the Coriolis effect from Earth’s rotation.
Continue reading “Flight Instruments”
At the cruising altitude of a jet airliner, Earth’s curvature is too slight for us to notice casually. But with planning and careful observation, it is not impossible to see the curvature. Continue reading “Observing Earth’s Curvature From a Flight”
Because Earth is a sphere, the horizon always lies below eye level. We cannot see it near Earth’s surface with the naked eye. But with a precise instrument like a theodolite, we can observe the dip of the horizon.
Flat-Earthers claim that the horizon always rises to eye level. In reality, even from very close to Earth’s surface, it is still possible to observe that the horizon lies below eye level.
Continue reading “Theodolite and the Dip of the Horizon”
A selenelion is a rare lunar eclipse where the Sun and the Moon are both visible at the same time. An even rarer form of selenelion occurs if it is a partial lunar eclipse, and the upper part of the Moon is eclipsed. Some call this an “impossible eclipse.”
Flat-Earthers claim that such an eclipse should not be possible to occur because the Earth’s shadow is in the wrong position. In reality, it is possible to happen because the observer is looking slightly downward due to the dip of the horizon and atmospheric refraction.
Continue reading “The Impossible Eclipse”
On many flights, they would give away leveling devices to all passengers for free, so that everyone would be able to observe the dip of the horizon and proves Earth is a sphere. And as a nice side effect, to quench our thirsts, too!
Such devices are called ‘bottled water’. Using these simple ‘instruments’ on a flight, we can demonstrate that Earth is a sphere.
Continue reading “Bottled Water: A Simple Device for Observing the Dip of the Horizon”