All 7 planets could fit between Earth and the Moon | Hacker News Reader

All 7 planets could fit between Earth and the Moon

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92 pointsdkpk62 comments

Given that the moon-earth distance varies, these planets would, twice a month at around the half moon, fit in exactly with no space left over

It varies between 360000km and 405000km ish https://en.wikipedia.org/wiki/Lunar_distance

Summing up the diameters of all planets (except earth) is 380018 km, which is between the range for the lunar distance. The average lunar distance is 384399 km.

https://science.nasa.gov/resource/solar-system-sizes/

The lunar distance from the Wikipedia entry is from center of earth to center of moon, so if we want to be more precise we would need to subtract the radius of both earth (6371 km) and moon (1737 km), in order to find the distance between their surfaces.

So on average we have: distance from surface of earth to the moon = average lunar distance earth radius - lunar radius = 384399 - 6371 - 1737 = 376291 km

Which means that putting all the planets side by side, starting from the surface of the earth, we could fit them but not on an average day, we’d need the moon to be a bit above the average distance :-)

This is true. At it’s closest distance (perigee), it would become crammed.

I'm pretty sure I've seen an infographic of this maybe a decade or more ago, but it was also a fact on No Such Thing As A Fish (the QI elves podcast) recently. I wonder if the Reddit poster picked it up from them.

https://pscrb.fm/rss/p/pdst.fm/e/arttrk.com/p/ABMA5/dts.podt... - "513: No Such Thing As Upside-Down Space Rain", 4m36

Shout out to AntennaPod, installed from F-Droid app store; far-and-away the best podcast listening app I've found.

> I'm pretty sure I've seen an infographic of this maybe a decade or more ago

The Reddit post is from 9 years ago so this checks out.

Lol, clearly I missed that, thanks for the info.

This is not quite what it seems.

What happens as you pile mass into a planet is that the planet becomes dense, not large, and this is because of gravity.

Jupiter has more than twice the mass of Saturn, but is only moderately larger in diameter.

You can keep dumping mass into a planet, and it just won't get much bigger, until you have enough mass that fusion kicks off, and then suddenly the now-a-star inflates, because it becomes extremely hot and then you have something the size of the Sun.

> What happens as you pile mass into a planet is that the planet becomes dense, not large, and this is because of gravity.

It's more complexe than this. Yes Jupiter is twice as dense as Saturn, but so is Uranus, which is much smaller.

Also the main reason for why Jupiter is just moderately larger than Saturn is that, at equal density, mass goes as the cube of diameter. If Jupiter had a density as low as Saturn, its diameter would only be 26% higher than it is today, and just 50% bigger than Saturn despite being 3.3 times as heavy.

So it's including the atmosphere in the radii of those planets (apparently one counts the atmosphere up to minimum 1 bar as part of the radius for gas giants).

Do we even know what's inside the gas giants, how big is the rocky core inside (if any)? Having probes dive inside of the gas giants for exploration would be an awesome space mission!

> Having probes dive inside of the gas giants for exploration would be an awesome space mission!

The Galileo mission to Jupiter carried a probe which dived into the atmosphere: https://science.nasa.gov/mission/galileo-jupiter-atmospheric...

"With about 8030 km or 4990 miles to spare"

So pluto could easily fit as well

According to Wolfram alpha, you could put in another Earth and two more Mercury's and still have 1600km leftover.

https://www.wolframalpha.com/input?i=%28earth+to+moon+distan...

This is mind blowing. Who would have thought the Moon was so far away?

Alternatively, this shows just how far the planets actually are from each other, relative to their diameters. Look for articles about "scale model of solar system" for some more interesting reading, e.g.:

https://www2.tntech.edu/leap/astr1010/sssm.html

some places also offer interplanetary hikes to scale

this one is 1:310^9, and it has feel-the-gravity weights for the planets, too:

https://sfeu.de/planetenweg/index.html

what I personally found mind blowing was insight into earth at scale. if you go for 1mm==10km then earth has 4m equatorial circumference, 1.28m diameter. bat that scale, Mt Everest is .8mm, the Mariana trench is 1.1mm

and the distance from Nuremberg where I live to Erlangen "next door" is 1.6mm, and Germany is the size of my hand, and.big enough to have visible curvature.

the outer 60km, that is 6mm at this scale, are solid, then it's dough, some places even pudding or outright liquid. the crust is* an eggshell, swimming on the inside of earth.

breathable atmosphere is just a teensy thin .5mm layer, overall it's 2mm.

such a model should be in every school, to me it's a deeply humbling experience, reminding me of the fragility of our habitat.

Like Sweden? https://en.wikipedia.org/wiki/Sweden_Solar_System

This is really interesting. Thanks for sharing!

https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.... is a hilarious linear scale model of the solar system (scale is that the moon is 1px).

Do be warned that for some people scale model of such scales trigger existential dread.

would be nice to also add the largest recognized dwarf planets, even though they are half the size of the moon.

Woah, this is mind blowing!

Next time you see the moon, cover it over with your thumb or index finger extended to arms length. The angular diameter of the moon (and sun, for that matter) are really tiny.

Your brain just imagines that you see it closer/bigger when looking at it, especially if it's near the horizon/through branches/other things on the ground. This effect gets more pronounced the longer you stare at it. I think this is why it's so hard to get a picture of the moon that looks like how you see it, unless you use an impractically long lens.

It also is perceived as being bigger when you shoot it with a sniper rifle because of the Marksman Target Salience Effect.

Lazy god dev.

A GTA reference.

https://news.ycombinator.com/item?id=38371361

Haha, nice one.

We really need some bugfixes to tidy up this place.

It's not a bug, it's a feature.

Sarcasm?

This is one of those things that seems incredible at first, but when you think about it, isn't actually that strange at all: Yes, some of these planets are massive, but the problem has always been (in observing or visiting them) their vast distance from Earth, not their actual sizes.

what makes it incredible is not the fact itself but the visualization and the realization of it.

i wasn't aware of the fact, and even though after thinking about it it's kind of obvious, the visualization really helps to let the fact sink in and make it memorable.

I'm confused.. I always thought the big planets were a lot lot larger than earth

And... indeed they are. But the diameters of each of the other planets combined are less than the average distance between the Earth and the Moon:

Average distance from Earth to the Moon:

Approximately 384,400 kilometers.

Diameters of the other planets:

Mercury: 4,880 kilometers

Venus: 12,104 kilometers

Mars: 6,779 kilometers

Jupiter: 139,820 kilometers

Saturn: 116,460 kilometers

Uranus: 50,724 kilometers

Neptune: 49,244 kilometers

For a total of 380,011 km, so 4,000 km to spare!

Does this account for most measurements being from the center of earth to center of moon?

So needs both max surface levels subtracted.

Good point. The image doesn’t mention but the calculations do subtract radii of both Earth and the Moon.

Another way of saying it is that the moon is surprisingly far away and it was a real achievement to visit there.

Even more than mars or other planets, I think of the distance to the moon in terms of light-seconds. About 1.5 seconds away. (really 1.3)

I had known this fact for a while, but the ending of portal 2 really solidified it in my mind.

Ha! I've been fighting the urge to make a portal 2 comment. What a wonderful game

I miss it.

I think the smarmy British bot character (Wheatley) won some kind of award.

They really did a fantastic job with Wheatley. The comedy style isn't for everyone (my wife for example hates it) but for me it is incredibly enjoyable

I bet he was the inspiration for Claptrap, in Borderlands.

Check the picture in the post. I'm pretty sure it is to scale.

They are much larger, but the moon is much further away from Earth than you imagined.

The thing is that it doesn't look to scale to me. But that's probably because most other visualizations/models are not right. Especially in the distances. I checked some other images and while the planets seem to scale, my brain multiplies the size of the planets with the distance ratio.

"But steel is heavier than feathers."

That is really cool. I will save that image.

It's a long way to the Moon.

But at such a congested space between them, chances are that gravity or magnetic fields on them will cause some havoc or the other.

Agreed, hopefully no one does this.

sigh Someone is going to make their own Occupy The Earth–Moon Distance t-shirts now.

It's called Cislunar space if you please.

You are now banned from Twitter.

you mean X'd on X

Surf would be way, way up though

I’ve put a warning sign over the big red button so we should be fine.

Oops - too late.

You have to admit it would be one of the coolest ways to go...

You're such a kidder.

Nobody would be that dastardly.

Are you saying someone might?

Super Jupiter soup. If it could pull in the asteroid belt too, who knows maybe start a red dwarf binary star system. Would be one hell of a ride in any case.

The sun contains 99.86% of the solar system's mass. Jupiter contains .2%. The other gas giants make up the rest, and everything else combined rounds down to zero. You could dump everything from Mercury to the Oort cloud into Jupiter and it's still not enough mass to turn it into a star.

I’ve heard that but would like to see for myself. Don’t forget about dark matter.

I think gravity would turn the whole earth into a sea of lava, or worse!

Let's hope God doesn't decide to play with their marbles.

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