Mars thread #2

[Ice Cream Jonsey]

My bedroom window points to the southern sky. My buddy Kurt told me that Mars should be extremely visible in just that direction and... I just looked. He was right.

I had just spent about the last ten minutes looking at it. It's gorgeous. I don't ever remember seeing anything so clearly in the night sky before aside from the moon.

Just looked something up -- Phobos is only 6,000 kilometers away from the surface of Mars. It's incredibly tiny, however. How much of the sky does it take up when it's overhead? It'd still have to be more than the Moon does for Earth, right? I need to find these things out.

[bruce]

Just looked something up -- Phobos is only 6,000 kilometers away from the surface of Mars. It's incredibly tiny, however. How much of the sky does it take up when it's overhead? It'd still have to be more than the Moon does for Earth, right? I need to find these things out.

Well, depends on what you mean by "how much of the sky". Let's assume you mean "area". Let's be generous to Phobos: it's 27 x 21 x 17 km, roughly, so let's call that 560 thingies (I'm multiplying the two largest dimensions, roughly. The pis and such are constants and so they'll divide out anyway, and what I'm interested in is a dimensionless constant: the size of Phobos relative to the size of the sky.) Now, it's 6000 km out, so let's call 1000 km our unit of distance, and say that, therefore, the inner surface of the sphere is 36 thingies (again, the pis and constants will all eventually cancel; what we care about is that the area of a spherical shell is proportional to the square of its radius). So the chunk of sky that Phobos takes up is 560/36, or roughly 16 mogelschnitzers.

Now on to Luna. It's about 1750 km radius, so let's call that 3500 km diameter. It's pretty close to round, so that's 12 and a quarter million thingies. But it's also much farther away: 380,000 km, more or less, so 380 units. Square that and you get 144,400. The chunk of sky that the moon takes up is therefore 12 and a quarter million divided by 144,400, which is roughly 85 mogelschnitzers.

So, sorry, ICJ, but the moon looks bigger from Earth than Phobos does from Mars.

Bruce

[bruce]

And just to piss on your parade a little more:

Phobos is roughly 6000 <i>miles</i> out. Its orbit is actually 9380 km. So it's really only about 6 mogelschnitzers, as opposed to the moon's whopping 85.

Sorry.

Bruce

[Ice Cream Jonsey]

So, sorry, ICJ, but the moon looks bigger from Earth than Phobos does from Mars.

Apology accepted.

Thanks for going through that, though. I've been up for far too long to really think it through and proofread anything so I am just going to do what my forefathers did and take it on blind faith.

[bruce]

take it on blind faith

You could always move to Alabama.

Bruce

[Ice Cream Jonsey]

Phobos is roughly 6000 <i>miles</i> out. Its orbit is actually 9380 km.

Yeah, but Mars is just over 6000 km wide. I may have misrepresented my position -- I was going on what it would look like on the surface of the planet, not what it would look like to Quaid, Melina, Benny and everyone else living in the center of the red planet.

Mars's diameter: 6,794 km
Phobos's orbit: 9,378 km

So half of Mars's diameter is 3397 km. Therefore the surface of Phobos is 5981 km away from the surface of Mars.

I was approximating when I said 6000. But I am not approximating anything when I say YUO=FAGOT. That's an equation that has been proven consistent with everything we know -- and continue to learn -- about the universe.

[Vitriola]

Yes, I got the link from slashdot, and no, it's not Mars, but this is cool:

Newest Hubble Shot

What does NGC stand for, again? And I mean acronymically, not politically, or morally.

[Ice Cream Jonsey]

Yes, I got the link from slashdot, and no, it's not Mars, but this is cool:

Newest Hubble Shot

What does NGC stand for, again? And I mean acronymically, not politically, or morally.

"New General Catalog" in astronomy, but on this BBS I think we were using it for NO GODDAMN CREDITS back when we were talking about arcade games that one time.

[Jack Straw]

What does NGC stand for, again? And I mean acronymically, not politically, or morally.

Nintendo GameCube?

[Ice Cream Jonsey]

What does NGC stand for, again? And I mean acronymically, not politically, or morally.

Nintendo GameCube?

Damn you, Straw. I spent 8 minutes thinking on this and could only come up with my crappy alternative.

Well played, Jack Straw. Well played.