[FPSPACE] Slooh: Watch Live Stream as Massive Asteroid Makes Close

David Portree dsfportree at hotmail.com
Tue Apr 18 22:19:16 EDT 2017

The "Lunar Distance" seems to be the preferred unit of distance in these "flybys." Most people don't know how far away that is, so it's scarily ambiguous. On at least one occasion we've heard about an asteroid flyby at more than 20 Lunar Distances. If that's meant to be scary, then we should be terrified when Venus is at inferior conjunction. I mean, it's huge, and hot, and flys by at about 100 Lunar Distances!

33 km sec would be about double average relative to Earth, but not that unusual.

Arecibo got radar images. As always, there's distortion, but it looks like a "contact binary." Very cool.

David S. F. Portree


dsfportree at hotmail.com<mailto:dsfportree at hotmail.com>



From: FPSPACE <fpspace-bounces at mail.friends-partners.org> on behalf of Robert G Kennedy III, PE <robot at ultimax.com>
Sent: Tuesday, April 18, 2017 5:31 PM
To: fpspace at mail.friends-partners.org
Subject: Re: [FPSPACE] Slooh: Watch Live Stream as Massive Asteroid Makes Close

They got the velocity way wrong.  Meant 33 km/sec, I'm sure.


On 2017-04-18 12:00, fpspace-request at mail.friends-partners.org wrote:
> Astronomers first learned about "The Rock" three years ago, when it
> was observed by the Catalina Sky Survey in Arizona.
> Not much is known about the asteroid itself, including its makeup
> and even its exact size. Estimates put it between 650 meters
> (about 2,000 feet) and 1.4 kilometers.
. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Here, the flack could have written "(about a mile wide)" and been
correct.  Lost chance.

> The asteroid will be moving at about 33 meters per second --
.                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

What's three orders of magnitude amongst friends?

> and come within 4.6 lunar distances of the Earth
.     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Gee, I wonder why they didn't put a converted imperial unit in
parentheses here, too?  Perhaps because "come within a million miles"
would have spoiled the drama?

Robert G Kennedy III, PE
1994 AAAS/ASME Congressional Fellow
U.S. House Subcommittee on Space
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FPSPACE at mail.friends-partners.org
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