Look up, attending down, attending out, attending around.
— Yes, “It Can Happen”
Good admonition from the 70s accelerating band. Attending about you. Unless you’re one of the Apollo astronauts, you’ve lived your absolute activity aural a few hundred kilometers of the apparent of the Earth. There’s a accomplished planet beneath your feet, 6.6 tillion bags of it, one abundance cubic kilometers of it. But how able-bodied do you apperceive it?
Below are ten facts about the Earth — the additional in my alternation of Ten Things You Don’t Apperceive (the aboriginal was on the Milky Way). Some things I already knew (and apparently you do, too), some I had annual about and had to do some analysis to check, and others I absolutely fabricated up. Wait! No! Kidding. They’re all real. But how abounding of them do you know? Be honest.
1) The Earth is smoother than a billiard ball.
Maybe you’ve heard this statement: if the Earth were diminished bottomward to the admeasurement of a billiard ball, it would absolutely be smoother than one. Aback I was in third grade, my abecedary said basketball, but it’s the aforementioned concept. But is it true? Let’s see. Strap in, there’s a wee bit of algebraic (like, a absolutely wee bit).
OK, first, how bland is a billiard ball? According to the World Pool-Billiard Association, a basin brawl is 2.25 inches in diameter, and has a altruism of /- 0.005 inches. In added words, it charge accept no pits or bumps added than 0.005 inches in height. That’s appealing smooth. The arrangement of the admeasurement of an adequate bang to the admeasurement of the brawl is 0.005/2.25 = about 0.002.
The Earth has a bore of about 12,735 kilometers (on average, see beneath for added on this). Application the accuracy arrangement from above, the Earth would be an adequate basin brawl if it had no bumps (mountains) or pits (trenches) added than 12,735 km x 0.00222 = about 28 km in size.
The accomplished point on Earth is the top of Mt. Everest, at 8.85 km. The centermost point on Earth is the Marianas Trench, at about 11 km deep.
Hey, those are aural the tolerances! So for once, an burghal fable is correct. If you shrank the Earth bottomward to the admeasurement of a billiard ball, it would be smoother.
But would it be annular abundant to qualify?
2) The Earth is an collapsed spheroid
The Earth is round! Despite accepted knowledge, bodies knew that the Earth was all-around bags of years ago. Eratosthenes alike affected the ambit to absolute acceptable accuracy!
But it’s not a absolute sphere. It spins, and because it spins, it bulges due to centrifugal force (yes, dagnappit, I said centrifugal). That is an outwards-directed force, the aforementioned affair that makes you angular to the appropriate aback axis larboard in a car. Since the Earth spins, there is a force apparent that is a best at the Earth’s equator, authoritative our Blue Marble appendage out, like a basketball with a guy sitting on it. This blazon of appearance is alleged an collapsed spheroid.
If you admeasurement amid the arctic and south poles, the Earth’s bore is 12,713.6 km. If you admeasurement beyond the Equator it’s 12,756.2 km, a aberration of about 42.6 kilometers. Uh-oh! That’s added than our altruism for a billiard ball. So the Earth is bland enough, but not annular enough, to authorize as a billiard ball.
Bummer. Of course, that’s d the altruism for actuality out-of-round for a billiard brawl is the aforementioned as it is for pits and bumps. The WPA armpit doesn’t say. I assumption some things abide a mystery.
3) The Earth isn’t an collapsed spheroid.
But we’re not done. The Earth is added complicated than an collapsed spheroid. The Moon is out there too, and the Sun. They accept gravity, and cull on us. The capacity are complicated (sate yourself here), but force (in the anatomy of tides) raises bulges in the Earth’s apparent as well. The tides from the Moon accept an amplitude (height) of almost a beat in the water, and maybe 30 cm in the solid Earth. The Sun is added massive than the Moon, but abundant further away, and so its tides are abandoned about bisected as high.
This is abundant abate than the baloney due to the Earth’s spin, but it’s still there.
Other armament are at assignment as well, including burden acquired by the weight of the continents, about-face due to tectonic forces, and so on. The Earth is absolutely a bit of a chapped mess, but if you were to say it’s a sphere, you’d be appealing close. If you captivated the billiard-ball-sized Earth in your hand, I agnosticism you’d apprehension it isn’t a absolute sphere.
A able basin amateur abiding would though. I won’t acquaint Allison Fisher if you won’t.
4) OK, one added surfacey thing: the Earth is not absolutely accumbent with its geoid
If the Earth were consistently elastic, afresh it would acknowledge advisedly to all these altered forces, and booty on a weird, adulterated appearance alleged a geoid. For example, if the Earth’s apparent were absolutely deluged with baptize (give it a few decades) afresh the apparent appearance would be a geoid. But the continents are not consistently ductile, so the Earth’s apparent is abandoned about a geoid. It’s appealing close, though.
Precise abstracts of the Earth’s apparent are calibrated adjoin this geoid, but the geoid itself is adamantine to measure. The best we can do appropriate now is to archetypal it application complicated algebraic functions. That’s why ESA is ablution a accessory alleged GOCE (Gravity acreage and steady-state Ocean Circulation Explorer) in the aing few months, to anon actuate the geoid’s shape.
Who knew aloof accepting the appearance of the Earth would be such a pain?
5) Jumping into aperture through the Earth is like orbiting it.
I grew up cerebration that if you dug a aperture through the Earth (for those in the US) you’d wind up in China. Turns out that’s not true; in actuality agenda that the US and China are both absolutely in the arctic hemisphere which makes it impossible, so as a kid I assumption I was appealing stupid.
You can prove it to yourself with this air-conditioned but contrarily abandoned mapping tool.
But what if you did dig a aperture through the Earth and jump in? What would happen?
Well, you’d die (see below). But if you had some abracadabra absolute blanket the walls of your 13,000 km abysmal well, you’d accept absolutely a trip. You’d advance all the way bottomward to the center, demography about 20 annual to get there. Then, aback you anesthetized the center, you’d alpha falling up for addition 20 minutes, slowing the accomplished way. You’d aloof ability the surface, afresh you’d abatement again. Bold you abandoned the air and compensated for Coriolis forces, you’d echo the cruise over and over again, abundant to your amusement and/or terror. Actually, this would go on forever, with you bouncing up and down. I achievement you bethink to backpack a lunch.
Note that as you fell, you advance all the way down, but the dispatch itself would abatement as you fell: there is beneath accession amid you and the centermost of the Earth as you arch down, so the dispatch due to force decreases as you access the center. However, the acceleration with which you canyon the centermost is considerable: about 7.7 km/sec (5 miles/second).
In fact, the algebraic active your motion is the aforementioned as for an orbiting object. It takes the aforementioned bulk of time to abatement all the way through the Earth and aback as it does to apogee it, if your apogee were appropriate at the Earth’s apparent (orbits apathetic bottomward as the alternate ambit increases). Alike weirder, it doesn’t bulk breadth your aperture goes: a beeline band through the Earth from any point to any added (shallow chord, through the diameter, or whatever) gives you the aforementioned biking time of 42 or so minutes.
Gravity is bizarre. But there you go. And if you do go booty the continued jump, well, your cruise may be a wee bit unpleasant.
6) The Earth’s autogenous is hot due to impacts, shrinkage, sinkage, and radioactive decay.
A continued time ago, you, me, and aggregate abroad on Earth was broadcast in a deejay about the Sun several billion kilometers across. Over time, this aggregated into tiny bodies alleged planetesimals, like bush asteroids. These would accurately together, and some would stick, basal a beyond body. Eventually, this article got massive abundant that its force actively drew in added bodies. As these impacted, they appear their activity of motion (kinetic energy) as heat, and the adolescent Earth became a aqueous ball. Ding! One antecedent of heat.
As the force increased, its force approved to drove the Earth into a added bunched ball. Aback you clasp an article it heats up. Advise ding! The additional calefaction source.
Since the Earth was mostly liquid, abundant being fell to the centermost and lighter being rose to the top. So the bulk of the Earth has lots of iron, nickel, osmium, and the like. As this being falls, calefaction is generated (ding advise ding!) because the abeyant activity is adapted to active energy, which in about-face is adapted to thermal activity due to friction.
And hey, some of those abundant elements are radioactive, like uranium. As they decay, they absolution calefaction (ding advise advise ding!). This accounts for apparently added than bisected of the calefaction central the planet.
So the Earth is hot in the central due to at atomic four sources. But it’s still hot afterwards all this time because the band is a appropriate insulator. It prevents the calefaction from artifice efficiently, so alike afterwards 4.55 billion years, the Earth’s autogenous is still an clumsily balmy abode to be.
Incidentally, the bulk of calefaction abounding out from the Earth’s apparent due to centralized sources is about 45 abundance Watts. That’s about three times the absolute all-around animal activity consumption. If we could abduction all that calefaction and catechumen it with 100% ability into electricity, it would absolutely ability all of humanity. Too bad that’s an insurmountable if.
7) The Earth has at atomic bristles accustomed moons. But not really.
Most bodies anticipate the Earth has one accustomed moon, which is why we alarm it the Moon. These bodies are right. But there are four added altar — at atomic — that stick a the Earth in the solar system. They’re not absolutely moons, but they’re cool.
The bigger is alleged Cruithne (pronounced MRPH-mmmph-glug, or article similar). It’s about 5 kilometers across, and has an egg-shaped apogee that takes it central and alfresco Earth’s solar orbit. The alternate aeon of Cruithne is about the aforementioned as the Earth’s, and due to the peculiarities of orbits, this agency it is consistently on the aforementioned ancillary of the Sun we are. From our perspective, it makes a awe-inspiring bean-shaped orbit, sometimes closer, sometimes further from the Earth, but never absolutely far away.
That’s why some bodies say it’s a moon of the Earth. But it absolutely orbits the Sun, so it’s not a moon of ours. Aforementioned goes for the added three altar discovered, too.
Oh– these guys can’t hit the Earth. Although they stick a us, added or less, their orbits don’t physically cantankerous ours. So we’re safe. From them.
8) The Earth is accepting added massive.
Sure, we’re safe from Cruithne. But amplitude is blowzy with detritus, and the Earth cuts a advanced aisle (125 actor aboveboard km in area, actually). As we break through this material, we accrue on boilerplate 20-40 bags of it per day! [Note: your breadth may vary; this cardinal is difficult to determine, but it’s apparently acceptable aural a agency of 2 or so.] Most of it is in the anatomy of diminutive dust particles which bake up in our atmosphere, what we alarm meteors (or cutting stars, but doesn’t “meteor” complete added sciencey?). These eventually abatement to the arena (generally transported by rain drops) and accession up. They apparently mostly ablution bottomward streams and rivers and afresh go into the oceans.
40 bags per day may complete like a lot, but it’s abandoned 0.0000000000000000006% the accession of the Earth (in case I miscounted zeroes, that’s 2×10-26 6×10-21 times the Earth’s mass). It would booty 140,000 actor 450,000 abundance years to bifold the accession of the Earth this way, so again, you ability appetite to backpack a lunch. In a year, it’s abundant catholic clutter to ample a six-story appointment building, if that’s a added acceptable analogy.
I’ll agenda the Earth is accident mass, too: the atmosphere is aperture abroad due to a cardinal of altered processes. But this is far slower than the bulk of accession accumulation, so the net affect is a accretion of mass.
9) Mt. Everest isn’t the bigger mountain.
The acme of a abundance may accept an absolute definition, but I anticipate it’s fair to say that it should be abstinent from the abject to the apex. Mt. Everest stretches 8850 meters aloft sea level, but it has a arch alpha due to the accepted boost from the Himalayas. The Hawaiian abundance Mauna Kea is 10,314 meters from axis to ascetic (um, OK, bad chat usagement, but you get my point), so alike admitting it abandoned alcove to 4205 meters aloft sea level, it’s a bigger abundance than Everest.
Plus, Mauna Kea has telescopes on top of it, so that makes it cooler.
10) Antibacterial the Earth is hard.
Considering I wrote a book about antibacterial the Earth a dozen altered means (available for pre-order on amazon.com!), it turns out the byword “destroying the Earth” is a bit misleading. I absolutely address about wiping out life, which is easy. Physically antibacterial the Earth is hard.
What would it booty to vaporize the planet? Let’s ascertain dehydration as alarming it up so adamantine that it disperses and cannot arouse due to gravity. How abundant activity would that take?
Think of it this way: booty a rock. Throw it up so adamantine it escapes from the Earth. That takes absolutely a bit of energy! Now do it again. And again. Lather, rinse, repeat… a quadrillion times, until the Earth is gone. That’s a lot of energy! But we accept one advantage: every bedrock we get rid of decreases the force of the Earth a little bit (because the accession of the Earth is abate by the accession of the rock). As force decreases, it gets easier to aish rocks.
You can use algebraic to annual this; how abundant activity it takes to aish a bedrock and accompanying annual for the blurred of gravity. If you accomplish some basal assumptions, it takes almost 2 x 1032 Joules, or 200 actor abundance abundance Joules. That’s a lot. For comparison, that’s the absolute bulk of activity the Sun emits in a week. It’s additionally about a abundance times the annihilative activity crop of atomic every nuclear weapon on Earth.
If you appetite to vaporize the Earth by nuking it, you’d bigger accept absolutely an arsenal, and time on your hands. If you blew up every nuclear weapon on the planet already every second, it would booty 160,000 years to about-face the Earth into a billow of accretion gas.
And this is abandoned if you annual for gravity! There are actinic bonds captivation the Earth’s bulk calm as well, so it takes alike added energy.
This is why Star Wars is not science fiction, it’s fantasy. The Death Star wouldn’t be able to accept a weapon that powerful. The activity accumulator abandoned is a bit much, alike for the ability of the Dark Side.
Even behemothic collisions can’t vaporize the planet. An article almost the admeasurement of Mars impacted the Earth added than 4.5 billion years ago, and the ejected bits formed the Moon (the blow of the collider alloyed with the Earth). But the Earth wasn’t vaporized. Alike smacking a accomplished planet into addition one doesn’t abort them!
Of course, the blow broiled the Earth all the way bottomward to the core, so the accident is, um, considerable. But the Earth is still around.
The Sun will eventually become a red behemothic (Chapter 7!), and while it apparently won’t absorb the Earth, it’ll put the aching on us for sure. But alike then, absolute dehydration is absurd (though Mercury is doomed).
Planets tend to be sturdy. Acceptable thing, too. We alive on one.
Well, that animated anticipation brings us to the end of my account of things you may or may not accept accepted about the Earth. I had lots more. How abundant does the atmosphere weigh? What’s the boilerplate accession of a cloud? Being like that, but these are the ten I admired best. If you’ve got more, feel chargeless to leave them in the comments!
But bethink the capital point here: you alive on a planet, and you may not apperceive all that abundant about it. The abandoned cure for that is learning, and that’s apprenticed by wonder. Accumulate wondering, and accumulate learning. And don’t balloon to attending around.
Original billiards images from Fictures.
GOCE angel address ESA.
Cruithne action from Wikipedia.
Mt. Everest aboriginal from Joe Hastings.
The nuked Earth angel was created by me for my additional Q&BA episode.
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