Update: Real #Science Answers to #FlatEarth Claims

Related articles linked at the foot of this page


Illustration of tangential rotational velocity using Doppler radio echo from the moon’s surface. The Earth rotates from West to East (Counter-Clockwise) and for the purposes of this illustration, the direction of rotation is depicted by the blue arrow. The uplink signal is nominal and on downlink, its frequency is shifted to a higher frequency (shorter wavelength) and with the signal thus depicted as blue.

One of the overarching beliefs of Flat Earth adherents is the claim that there exists no empirical evidence for the Earth’s curve or rotation. Aside from the standard, obvious proofs presented in our articles published thus far on this topic, proofs that include Star Trails for both hemispheres, diurnal motion, changing elevation for Polaris based on latitude, telescopic observations of solar system objects, the Foucault pendulum, eclipses, etc., I present a new, incontrovertible proof of Earth’s rotation and associated tangential velocity. This new method uses Doppler radio echo from the lunar surface, a method whose accuracy has a precision of at least four decimal places based on the accuracy and sensitivity of the radio transceiver.


1.6 Km (1 mi) section of the 3.2 Km antenna array in western Texas.

The broadcast antenna is an array of 2,560 individual dipole antennas 3.2 Km (2 mi) in length located in west Texas, approximately 160 km (100 mi) west of Dallas. It transmits a nominal carrier signal with 6 gigawatts ERP (Effective Radiated Power) at 216.9800 Mhz. Such a combination of sufficiently high frequency that the ionosphere is completely transparent (the ionosphere is transparent to any signal above 30 Mhz) and very high ERP allows the signal to easily reach the moon and provide a detectable echo on downlink to the receiver.

Doppler technology is used almost everywhere in our everyday life, from police radar speed detectors to Doppler ultrasound medical applications. The technology is mature and very reliable. Using Doppler radio technology, radial velocity studies of our Milky Way galaxy have been conducted with an extremely high degree of precision.


A Doppler cross sectional view our Milky Way galaxy illustrating its radial (rotational) velocity as seen edge-on from our vantage point 25,000 light years from the center. Unlike the data from the lunar radio echo, the galaxy rotates clockwise as observed from above (North) and thus, the trailing (red-shifted) aspect of the image is on the right. The galactic center, the subject of several recent, high-value studies is at the center of the image.

It must be noted that the originator and owner of this website, the source of the data used here, serendipitously and quite by accident, is a licensed amateur radio operator with call sign W5SXD. He and a colleague successfully engaged in similar experiments back in 1972. The rising moon is an ideal target for a radio echo study and was thus used in this case to determine the tangential velocity of the Earth at the transmitter’s location – the transmitter is being rotated towards the moon. As the moon continues to rise and approach the meridian, the return echo will approach the nominal transmission frequency; as the moon continues west of the meridian, the return echo will be increasingly red-shifted and the signal from the setting moon will be red-shifted by the same magnitude as the the signal from the rising moon was blue-shifted.


Receiver output of the 216.98 Mhz signal showing many jet aircraft and, most importantly, the 365 Hz blue-shifted radio echo from the rising moon. If the capture were conducted when the moon was west of the meridian, the signal would be increasingly red-shifted.

Applying the simple Doppler relation to determine velocity, where the change in frequency relative to the base frequency is directly proportional to the velocity of the object relative to the speed of light: and solving for v, the tangential velocity of the Earth’s surface towards the moon at the location of the radio transmitter, we find: . Substituting and solving for the velocity:
The surface of the Earth at the location of the radio transmitter (33°33’N x 98°45′ W) is rotating with a tangential velocity of

0.5043 km/sec converts to 504.3 m/sec or 1,815.48 km/hr (1,128 mi/hr) and is consistent with the result obtained using the Earth’s solar day (24 hours) of 465 m/sec.

The Doppler method thus confirms the value obtained using the Earth’s solar day.

Related articles
The #FlatEarth Phenomenon DeBunked, Part I (video)
Update: Real #Science Answers to #FlatEarth Claims
Real #Science Answers to #FlatEarth Claims
The #EarthIsFlat (and other #nonsense)
In A Demon-Haunted World, #Science As A Candle In The Dark

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