4 ms·

> this is a very tiny change There! That's what I was looking for. So they were expecting a miniscule change, and instead they were pleasantly surprised by the

• bmlzootown 4y ago
  I mean, they quote Ian Carnelli in the article, saying that he expects a "much bigger deflection than (he) had planned". That said, the article also mentions that it will take Earth-bound telescopes/radars at least a week to get initial estimates in regard to the change of the asteroid's orbit, and then three to four weeks before getting precise measurements. I think the real takeaway here is just that something unexpected happen. They're monitoring as they would have regardless, and results will come in time. Expecting results and/or a conclusion this early is, well, jumping the gun.
• shagie 4y ago
  The orbit of Didymoon around around its primary is about 4in/s or 10cm/s. Wolfram gives its comparison to the speed of a garden snail. They are hoping to see a change in its velocity of a fraction of a mm/s. https://youtu.be/U0nZvOm3bNs?t=415 https://youtu.be/U0nZvOm3bNs?t=415 It is a small value, but its a measurable fraction of the the velocity of its orbit around the primary (about 12h). They know the momentum that the impacter had. They had an estimate of the mass of Didymoon and its velocity. They are interested in how much of that momentum was transfered to Didymoon and how much was carried away from ejecta.