dai bread wrote:Chilling. 5.3 lunar distances seems too close for comfort. That one's coming in April. What's the margin of error in these tables?
I wish i knew... guess it depends on how close they can resolve an angle , i'd guess the distance is a few percent. All the gravitational tugs on them steer them - it must be a lengthy computer program to figure all that in 3-D.
ANECDOTE ALERT - one evening about sunset in 1989 0r 1990 i had my 4 inch telescope in the front yard showing the neighbors the full moon... we saw something bright approaching the moon from south at a good clip, and it was big enough to be a visible disc.... it crossed the moon on this side.... I was excited to say the least. But the next day's news said nothing so i concluded it had to be a weather balloon, surely a satellite wouldn't show a disc at just thirty power.
Well about a month(? week or two? can't recall) later the news said astronomers had spotted a big previously unknown asteroid that had come close to earth, i think 1.05 lunar orbit units, and was now heading away. They said it had been a close call and they'd missed it coming. Well , if that was what we saw it came a lot closer than they think.
I will always wonder.
Did the Earth almost get hit by an asteroid on March 23, 1989?
Sky and Telescope magazine for June 1989 page 592 reports that on March 22-23 there was a near miss which went un notices by strong moonlight but the object was detected 8 days later and cataloged as 1989FC. It was 300 meters in diameter and passed within 690,000 kilometers of the Earth. However, the asteroid was discovered on March 31, 1989 after it had passed the closest point to the Earth. Earth moves 700,000 km in about six hours. The mean distance of Moon from the Earth is 384,404 km.
there's quite a bit about that asteroid on net now. Early estimates ranged as close as 46,000 miles, later ones placed it outside lunar orbit (240Kmiles). So i don't know just how exact is the science.
And i still wonder if we might have seen it.
Cogito ergo doleo.