-Z- (z@gundam.com)
Mon, 19 Jun 2000 20:02:01 -0700


> -----Original Message-----
> From: owner-gundam@1u.aeug.org [mailto:owner-gundam@1u.aeug.org]On
> Behalf Of Neil Baumgardner
> Sent: Sunday, June 18, 2000 17:05
> To: gundam@aeug.org
> Subject: Re: [gundam] Colony Drop
>
>
> -Z- wrote:
>
> > Luna 2 is a mere 244 km (150 miles) "Wide" -- about 7% of the Moon. That's
a
> > little over two minutes of arc. It would, I think, appear as brighter than
> > average planet, perhaps with a distinctive color. It would probably show as
a
> > disc, albeit a lopsided one.
>
> Whoah, you mean pre-0070 right? By that time its moved to near Side 7. Or are
you
> saying it would still be that visible? For that matter, how visible would
Solomon
> or A Bao A Qu be?

Luna 2 has the dimensions given here. Asteroid 3 Juno, which was whittled down
into Luna 2 during the construction of the Sides, was originally 290 km (180
miles) across.

As to the visibility, that's a function of both distance and "albedo" -- the
amount of light that it reflects back into space. Earth, for example, has an
albedo of 0.39, while the Moon has an albedo of 0.12 -- the Earth is thus three
times as visible as the Moon. I don't have any albedo information on the
asteroids handy, but Juno/Luna 2 has a "stony" rock and iron surface, comparable
to the Moon, which has a basaltic dust and rock surface. I'd expect an albedo
in the range of 0.10 ? 0.05, which would certainly be quite visible from
anywhere on Earth.

It should be noted, however, that, unlike planets, asteroids are not spherical
and regular and that their shapes and irregularities will have an effect on
their albedo. Where a perfectly spherical body with a perfectly uniform surface
would show constant brightness, an elongated body would display two brightness
peaks per revolution, corresponding to the two side views. A body with large
randomly distributed bright and dark spots would show a complex variation of
brightness with time during each rotation, but the entire pattern would repeat
itself with fidelity during the next rotation.

-Z-

-
Gundam Mailing List Archives are available at http://gundam.aeug.org/



This archive was generated by hypermail 2.0b3 on Tue Jun 20 2000 - 12:02:18 JST