Would you like Titan as our Moon?

A silly question, but an excuse to see how Titan differs from our
lovely Moon!

Titan is bigger for starters, in diameter big enough to take up about
3/4 degrees in the sky rather than the usual 1/2 were it orbiting at
the same place. (that means a cheap 60mm telescope would be fine!)
It's getting on for twice as heavy too (but not quite), so expect some
bigger tides. had it been there from the outset i'd imagine our day
would be longer than 24 hours by now.

Ironically though, Neil Armstrong would feel lighter when visiting -
despite Titan taking up 3 times the volume of space compared to the
Moon and being much heavier, the size of Titan means that the
gravitational acceleration at the surface is less than on the Moon's
surface, around 1.3 m/s as opposed to 1.6 m/s (earth being 9.8). it
wouldn't feel that different, but a 75kg man on earth weighs 12.4Kg on
the Moon and 10.4kg on Titan. The Moon is very densely packed compared
to Titan it seems.

if we thought we'd see a lovely atmospheric Titan-Moon glinting in the
sky though we'd be dissapointed - that atmosphere and any interesting
liquids on the surface would have boiled into space very early on and
leave something looking very much like our Moon anyway!

for reference i've used the following data:

radius: Moon 1737km, Titan 2575km
weight: Moon 7.35e22 kg, Titan 1.35e23 kg

and some calculations for volume, esc vel and angular diameter, which i
cannot guarantee the accuracy of!

Why is the Moon so dense anyway? Other than Io it seems to be the
densest satellite in the solar system, and Earth is just about the
densest planet. The 'small mars-like planet collision theory' perhaps?
or just the effect of forming close to the Sun where the "lightweight"
material gets solar windswept away?

wrote:

A silly question...

I think that says it all.

Davoud

--
usenet *at* davidillig dawt com

wrote:
A silly question, but an excuse to see how Titan differs from our
lovely Moon!

Our moon sucks. I'd take even Amalthea or Deimos over our crappy,
monochrome moon! Titan would be far better.

wrote:
wrote:

A silly question, but an excuse to see how Titan differs from our
lovely Moon!

Our moon sucks. I'd take even Amalthea or Deimos over our crappy,
monochrome moon! Titan would be far better.

Titan?! I don't think so. If it comes to visual observing, it
would look like a whitish featureless sphere. On the other hand,
I'd happily swap our moon for Phobos and Deimos - not gravitationally
locked, smaller (so no problems with the excess light that ruins
half of the weekends for DSO observing), and generally more fun to
look at. On the negative side, there won't be any full solar
eclipses, but well, one can't have everything.

- Alex

Alexander Avtanski wrote:
Titan?! I don't think so. If it comes to visual observing, it
would look like a whitish featureless sphere. On the other hand,
I'd happily swap our moon for Phobos and Deimos - not gravitationally
locked, smaller (so no problems with the excess light that ruins
half of the weekends for DSO observing), and generally more fun to
look at. On the negative side, there won't be any full solar
eclipses, but well, one can't have everything.

I believe both Phobos and Deimos are gravitationally locked, in the
sense that they always present the same face to the Martian surface.
Naturally, they have failed to lock Mars in the same way, but so has
our Moon. The only satellite known to have locked its parent is
Charon. Pluto and Charon both present the same face to each other
at all times. There's an entire half of Pluto that hasn't seen Charon
(and vice versa) since early on in the history of our solar system.

Phobos and Deimos do have the advantage that, because they are so
small, they are held together more strongly by electromagnetic forces
(the sort that hold together the chair you're sitting on) than by
gravitational forces. As a result, they're not spherical, and have
a more immediately interesting morphology than the Moon.

Our Moon, on the other hand, has a lot more surface area for things
to happen on. It has craters which would have split Phobos wide open
(and goodness only knows what they would have done to Deimos), and
it was at some point in the past geologically active, which leads to
a number of features that can be seen from the Earth. All in all, I
think our Moon is quite fascinating.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Brian Tung wrote:

I believe both Phobos and Deimos are gravitationally locked, in the
sense that they always present the same face to the Martian surface.

[ ... ]

My wrong. Then what was the one that was kind of tumbling randomly?
Maybe this was an asteroid, but somehow, somwehere in the disty corners
of my mind I have some hazy recollections about a small moon (?) that
tumbles quite chaotically. Evidently it's not Phobos nor Deimos.

Wait a minute. I just remembered and checked it - it's Hyperion.
How about Hyperion then?

- Alex

Alexander Avtanski wrote:
My wrong. Then what was the one that was kind of tumbling randomly?
Maybe this was an asteroid, but somehow, somwehere in the disty corners
of my mind I have some hazy recollections about a small moon (?) that
tumbles quite chaotically. Evidently it's not Phobos nor Deimos.

Wait a minute. I just remembered and checked it - it's Hyperion.
How about Hyperion then?

Hyperion lies about 1.4 million km from Saturn cloud deck and is, in
its greatest extent, about 400 km across. That means it subtends about
1 arcminute. Not much to see by the unaided eye, but its telescopic
view would probably be pretty interesting.

Now, if it were moved to the Moon's place, next to the Earth, it would
lie a mere 380,000 km from us, and would then subtend about 3 arcminutes.
Still not tremendously exciting by the unaided eye (although you could
probably tell it wasn't round, if you have excellent eyesight), but
definitely an interesting view with a telescope.

There's some thought, however, that Hyperion's unusual rotation is only
sustained because of a resonance with Titan. If so, it could be that
even as small as it is, the Earth would have tidally locked it by now,
if it were the only sizable satellite in orbit around the Earth.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

never seems to occur to him Titan could not be our moon!



Davoud wrote:

wrote:

A silly question...

I think that says it all.

Davoud

--
usenet *at* davidillig dawt com

Warm Nights wrote:
never seems to occur to him Titan could not be our moon!
you may have taken the post too seriously!