On Mon, 29 Aug 2005, vswmart wrote:

> Hello all,
>
> I would like Guide to be able to create a list of the currently
> nearest objects/asteroids/comets.
>
> Similar, a list of the objects, which currently have the largest
> apparent motion in the sky.
>
> That would be nice for public presentations with bigger scopes or
> imaging, like: Look over there, that is the moon, as we all know,
> usually the nearest object. But whats the next one after the moon???
> Venus? Mars? Or something else?

Usually it's some NEO - Near Earth Object, almost always an asteroid.
Occasionally a NEO gets closer to us than the Moon does.

Among the naked-eye objects, Venus or Mars is usually the second
closes object. Sometimes Mercury is the second closest. And
sometimes - when Mercury, Venus and Mars all are on "the far side
of the Sun", the Sun itself will be the second closest celestial
object.

Of course we also have all our artificial satellites, most of which
are closer than the Moon, and at least one of which (the ISS) is as
large as the smallest NEO's detected to have passed closer than our
Moon. The NEO is solid rock though, while the ISS is mostly hollow
so the ISS is probably less massive.

> As the distances/positions are calculated anyway for display, this
> should not be to hard. Or is it possible already and i just missed it?

If you want to include only naked-eye celestial objects it's easy
enough.

But if you also want to include faint NEO's, this calculation would
include a search through a fairly large database of known NEO's,
making sure you use up-to-date orbital elements, or performing a
numerical integration to update these elements.

> Regards, Martin

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