4 ms·
What you're describing is known as Constant Bearing, Decreasing Range (CBDR), https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_range https://en.wikipe
by EA-3167 2y ago
What you're describing is known as Constant Bearing, Decreasing Range (CBDR), https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_range https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_r... and generally doesn't apply to to the case of a nearby asteroid on a collision course with Earth. For the parallax created by our orbit to be negligible, the object would have to be very distant.
- mjcohen 2y agoThe way I heard this is, at a military site, "No change in azimuth. No change in elevation. Let's get the hell out of here!"
- phkahler 2y agoCBDR only requires constant velocity. Similar triangles are all you need. On short time scales even orbits are approximately straight. It still applies and may well be the reason this one was missed until so close.
- Modified3019 2y agoSounds related to motion camouflage, which dragonflies use to hunt. Allows them to appear stationary, with the only sign they are on an intercept course is looming as their image slowly grows larger. https://en.m.wikipedia.org/wiki/Motion_camouflage https://en.m.wikipedia.org/wiki/Motion_camouflage