I Hear and Obey
Posted on April 23, 2008 Posted by John Scalzi 19 Comments
Krissy, on the phone to me as she drives home: “You need to go and take a picture of the sun right now!”
Here’s a thought: Gravitationally speaking, the sun is 93 million miles down from us. And we would fall all the way in. Yes we would.
And here I thought the sun was the size of quarter and set in Arizona. Things you learn.
We wouldn’t fall in. We’d burn to carbon dust before that could happen and the solar wind would scatter our remains to the far corners of the Solar System.
Remember, the enemy gate is down.
A more reasonable gravitational definition of down would say that “down” is towards whatever body exerts the greatest gravitational force on you. Thus the sun is only “down” once you get outside of Earth’s gravity well.
Gravitationally speaking, the sun is 93 million miles down from us. And we would fall all the way in.
Great. Just go ahead and give my brain more ideas to fuck with me as I’m falling off to sleep. As if falling off small cliffs isn’t enough…
(Couldn’t sleep well for a week after I saw Sunshine, which this wisecrack also reminds me of. I managed to compress a giant lunchtime burrito into a doughy little ball bearing during the course of that movie.)
We are falling in! We keep falling in! Forever! That’s the whole point!
One would imagine a published author of a popular astronomy book would know this…
Could we have a big version please?
But all you need to keep from burning up is a magic mirror.
Oh, and a crazy crispy monk. That helps. Then you can have transcendence too.
I can tell none of you are orbital dynamicists.
There is no down when you’re in orbit. You have a potential and kinetic energy balance. Down is when you have more potential energy than kinetic.
There’s a special case for this, where you’re on an orbit that intersects an object or its atmosphere, or close enough to an atmosphere that delta KE / delta T is significant. Those are less “down” than “impending splat”, though.
Pretty central gravitational body picture, though.
“Wheeeee!” –Akktri the Phner
Well, sorta… If you got free of Earth’s gravity, you’d be in some orbit around the Sun, with the Sun being the center of attraction, but you’d still have the momentum of an object in orbit at Earth’s distance. It takes more energy to kill that momentum and fall into the Sun than it takes to go completely out of the Solar system. (Really! It takes more energy for a spacecraft to get to Mercury than to Pluto.)
All that aside, great pic. Thanks for posting it.
I thought that the enemy’s gate is down. Great sunset, though.
Speaking from the position (vector) of someone who knows next to nothing about orbital dynamicism, I’m feeling really queasy now. This is like when you see clouds moving through the sky and for a second you think the clouds are still with the Earth rotating below them, and then you have to go and lie down.
It takes more energy to kill that momentum and fall into the Sun than it takes to go completely out of the Solar system. (Really! It takes more energy for a spacecraft to get to Mercury than to Pluto.)
That is truly fascinating. IIRC it also takes less energy to go from Earth orbit to Mars than from Earth to the Moon – because you can aerobrake at Mars.
Earth is well inside the heliosphere, so we’re already there.
That is sooooooo beautiful. I do the same thing to my husband… MUST TAKE PICTURE OF THE SUNSET NOW!
Thus, I have *way* too many pictures of sunsets…
Well, now I’ll be singing the They Might Be Giants song all night. Not that that’s a bad thing.
#2: No, we’d go at night.
She should have said “jog out past that aircraft hangar and take a picture RIGHT NOW.”