Talk:Radar astronomy

1945?[edit]

Is the 1945 date for the first observation of the moon with radar correct? Project Diana bounced radar beams off the moon on January 10, 1946, which is generally considered to be the first time radar pierced the ionosphere. Is this just a typo?

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Meaning of Doppler images[edit]

I find it hard to find explanations of what we're seeing in these radar images, and with 2003 SD220 flying by, and its apparent elongated shape, it makes more curious again. My best understanding is the vertical axis is time delay, so things at the top are closer, and brightness is probably related to the flatness of a surface, so orthogonal surfaces will reflect strongly, while glancing reflections on the sides are weaker. And then the horizontal axis is the doppler shift variations. So its overall motion gives a central doppler shift while the rotations of the body produce local doppler shifts, with perhaps the left side for parts moving away from us, and right side moving towards us. So with delay, doppler shift and intensity, you can produce a 2D map that gives an illusion of a 3D object seen perpendicular to the actual viewing location. I also see observing over time will produce the rotation period, and knowing that you can try to calibrate the horizontal scale into an effective distance measurement, so a spherical body will look spherical. But if a body is elongated like 2003 SD220, radar images may give a distorted perception of its proportions.Tom Ruen (talk) 00:19, 23 December 2018 (UTC)[reply]

Rotation of Venus[edit]

I can't find any evidence that the rotation period of Venus was determined in 1961 as stated. The December 1964 issue of Sky and Telescope, page 341, in an item about the rotation period of Venus based on a talk by I I Shapiro given at the Hamburg IAU General Assembly, said that in 1961 all that could be inferred was that the rotation was slow. In 1962, observations by both Soviet and JPL scientists indicated that the rotation was retrograde but values of between 248 and 300 days were given. Not until 1964 was the period established as 247 +_ 5 days. Robin Scagell (talk) 17:32, 16 July 2023 (UTC)[reply]