Tag: science

How Old Are Saturn’s Rings?

~ J.S. Pailly ~ 4 Comments

Hello, friends!

I love Saturn’s rings, you love Saturn’s rings, everybody loves Saturn’s rings!  And as you can see in the 100% real, totally legit J.W.S.T. image below, even Saturn is a little obsessed with her own rings.

Those rings are iconic!  They’re also mysterious.  Did Saturn always have rings like that, or were they created more recently (perhaps by the destruction of a Saturnian moon)?  The answer depends on which scientists you ask.

Saturn’s rings are mostly made of ice, the frozen water kind of ice (as opposed to methane ice, ammonia ice, nitrogen ice… lots of things turn into ice in space).  But the rings aren’t a pure, icy white color.  Like a pile of snow near the curb of a highway, Saturn’s rings get dirtier and dirtier over time.  Based on how dirty the rings look today, some scientists believe they can calculate how old the rings must be.  And according to those calculations, Saturn’s rings must have formed between 100 million and 400 million years ago.  That may sound like a long time ago, but in cosmic terms that makes the rings surprisingly new.

However, there’s also research suggesting that Saturn has self-cleaning rings.  Basically, here’s how that would work: when dirt and dust particles from space enter Saturn’s ring system, those particles are moving at extremely high speeds.  High speed collisions vaporize the dust particles.  The vaporized dust undergoes gaseous expansion. Most of the expanding gas then leaves the ring system due to a combination of its own momentum plus Saturn’s gravity plus Saturn’s magnetic field.  If this is true, the rings still get dirtier and dirtier over time, but at a much slower rate.  This means the rings could be up to 4.5 billion (with a b) years old.  In other words, the rings could be as old as Saturn herself.

When new scientific research comes out, I think people get the wrong idea about what that means.  I blame Hollywood, and I blame the media.  Whenever a new scientific paper is published, it’s often portrayed as the final, definitive word of science.  Until another paper comes out, contradicting the first.  Then that’s portrayed as the final, definitive word of science.  Until another paper comes out.

But science is more like an ongoing, back-and-forth conversation.  One paper comes out, making a point.  Another paper follows, making a counterpoint.  Then there’s a counterpoint to the counterpoint, and then a counterpoint to the counterpoint of that counterpoint… and so on and so forth, until eventually (hopefully) the scientific community reaches some sort of consensus.

So how old are Saturn’s rings?  Well, while researching this blog post, the most recently published paper I saw said 4.5 billion years; however, I think this is still an ongoing conversation.  New points are still being made.  New counterpoints are still being offered.  Maybe the rings are super ancient, or maybe they’re relatively young.  Science has figured out a lot of things, but on this question about Saturn’s rings, I think we’re still waiting for the scientific community to reach a consensus.

WANT TO LEARN MORE?

Maybe Saturn’s rings relatively young.  Click here to read more about that, or click here to see an actual research paper on that hypothesis.

Or maybe Saturn’s rings are super old.  Click here for an article on that, or click here to see the actual research.

Okay, I lied.  That wasn’t really a J.W.S.T. image of Saturn.  I drew that myself.  If you like my drawings, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting and maybe clicking the like button on my art helps me a lot. Thank you, friends!

The Other Moon Race: Jupiter vs. Saturn

~ J.S. Pailly ~ 2 Comments

Hello, friends!

As you know, there’s a new moon race going on, a new race to return humans to the Moon!  But that’s not the moon race we’re talking about today.  No, today we’re talking about the race between Jupiter and Saturn to be the planet with the most moons in the Solar System.

You might expect Jupiter to win this easily.  Jupiter’s the biggest planet, and Jupiter has the most gravity.  Shouldn’t Jupiter end up with the most moons?  Well, Saturn has one not-so-obvious advantage over Jupiter: Saturn is farther away from the Sun.  That means a moon orbiting Saturn is less likely to be yanked away by the Sun’s gravity than a moon orbiting Jupiter.

This has to do with a concept in astrophysics called the Hill sphere, named after American astronomer/mathematician George William Hill.  This can get a bit technical, so if you want to learn more please check out the “What to Learn More?” section below.  This gist is this: a Hill sphere is the area around a planet where the planet’s gravity is more important than the gravity of the Sun.  The size of a Hill sphere is determined by two factors: how massive is the planet, and how far away is the Sun?

Saturn may be smaller than Jupiter, and she may have less gravity than Jupiter, but she’s so much farther away from the Sun that she ends up having the larger Hill sphere.  So which planet has the most moons?  Well, over the past few decades, as astronomers have discovered more and more moons orbiting each planet, it’s been a bit of a horserace.  Sometimes Saturn’s ahead by a couple moons, then Jupiter will catch up and take the lead, then Saturn will take the lead again for a while, and so on.

But in the last year or so, that’s changed.  Saturn has surged way ahead in the “moon race.”  At the time of this writing, Jupiter is known to have 115 moons.  Saturn, meanwhile, has 292.  We can safely assume that more moons will be discovered orbiting both planets, so the race isn’t over; however, I’m going to make a prediction now.  I don’t think Jupiter’s going to win this.

I don’t think Saturn will win, either.  There are (at least) two more planets farther away from the Sun than Saturn.  If having the biggest Hill sphere is the key to winning this moon race, Neptune’s Hill sphere is larger than Jupiter and Saturn’s Hill spheres combined (and if the Planet Nine hypothesis turns out to be correct, God only knows how large Planet Nine’s Hill sphere must be).

At the moment, Neptune is only known to have 16 moons.  I’m predicting today that as our telescopes continue to advance and as our observing techniques continue to improve, Neptune’s moon count will go up.  By a lot.  Ultimately, I’m predicting that Neptune’s total moon count will exceed Jupiter’s and Saturn’s by far.

WANT TO LEARN MORE?

Here’s an article from CosmoBC on Hill spheres, including a chart listing the radius of the Hill spheres of each planet of the Solar System (plus a few of the dwarf planets).

Here’s an article by Phil Plait on how the Moon stays in orbit by staying inside Earth’s Hill sphere.  It’s an older article, but it’s still very much worth a read if you want to understand how Hill spheres work.

Here’s an article from Earth Sky on the current totals for Jupiter’s  and Saturn’s moons.

And here’s another article from Earth Sky on the total number of moons for Uranus and Neptune, with a little information about why discovering moons orbiting Uranus and Neptune is still so difficult for us.

Lastly, I mentioned the Planet Nine hypothesis.  If you don’t know what that is, click here.

The art in today’s post is my own original work.  I don’t use A.I. for anything, ever.  If you like my art, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting my store and clicking the like button on a few things helps me a lot.  Thank you, friends!

Mercury in the Sky with Diamonds

~ J.S. Pailly ~ 6 Comments

Hello, friends!  Today’s post is mainly intended for Sci-Fi writers, but I’m hoping others will find it interesting, too.

Mercury, the planet closest to the Sun, perhaps the most overlooked and under-appreciated planet in the Solar System, may possess a precious and beautiful secret: diamonds.  So many diamonds!  Tiny diamonds may be scattered all across Mercury’s surface, with even more diamond buried deep, deep, deep underground.

Superficially, Mercury looks a lot like Earth’s moon.  They’re both rocky, airless worlds peppered with impact craters.  They’re both kind of grey, except Mercury is a darker shade of grey than the Moon.  That darker color is caused by graphite (the same graphite found in pencil lead).

For whatever reason, when Mercury first formed, it ended up with an overabundance of carbon (and an underabundance of stuff that would normally react with carbon).  As a result, carbon atoms combined with other carbon atoms to produce plain, simple graphite.

But as I said, Mercury (like the Moon) is covered with impact craters.  A whole lot of impact craters.  In fact, Mercury is the #1 most heavily cratered planet in the Solar System.  And so, whenever an asteroid or comet rammed full speed into Mercury, the force of that impact would have put Mercury’s graphite under sudden and extreme pressure—enough pressure to compress ordinary graphite into diamond.

According to one source I read (see the “want to learn more?” section below), there’s an estimated 16 quadrillion tons of diamond on Mercury’s surface.  That’s about 16 times more diamond than the estimated total amount of diamond we have here on Earth.  But wait, there’s more!  According to another source I read (again, see the “want to learn more?” section below), Mercury may also have a layer of pure diamond buried deep underground.  This diamond layer would be roughly 10 miles thick, and it would lie roughly 300 miles down.

Given that synthetic diamonds already exist, would Mercury’s superabundance of diamonds be worth anything in the distant future?  I don’t know, but I feel like there’s potential here for a Sci-Fi story.  Whenever I learn a weird and quirky science fact like this, I treat it like a writing prompt and see if any good Sci-Fi ideas come out of it.

But I don’t have any plans to write a story about diamond mining on Mercury, which is why I’m sharing this weird and quirky science fact here on the blog, so other Sci-Fi writers can read this and ponder over it.  The planet Mercury is brimming with diamonds—way, way more diamonds than we have here on Earth.  How would you use that science fact for science fiction?

WANT TO LEARN MORE?

Here’s an article from Science News explaining how impact events on Mercury create diamonds on Mercury’s surface.

And here’s an article from Live Science explaining how a 10 mile thick layer of diamond might have formed deep beneath Mercury’s surface.

Also, I did another post on Mercury just a couple of weeks ago.  If you want to learn a few more fast facts about Mercury, click here.

The art featured in today’s post is my own original work.  If you like my art and want to support what I do on this blog, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting and clicking the like button on some of my work would help me a lot (and obviously, if you do end up buying something, that would help me even more!).

Thank you, friends!

Mercury’s #1

~ J.S. Pailly ~ 9 Comments

Hello, friends!

I love Mercury.  He’s the planet closest to the Sun, which makes him the first planet of our Solar System.  Sadly, that seems to be the limit of what the average person knows about Mercury, so today I’d like to share just a few other ways Mercury wins first place.

First off, if there were a footrace among all the planets of the Solar System, Mercury would win.  Easily.  Mercury is the #1 fastest moving planet in the Solar System.  This has a lot to do with Kepler’s laws of planetary motion and Netwon’s law of universal gravitation, but I think I can explain this without digging into Kepler or Newton’s math.  Imagine you’re a planet and you don’t want to fall into the Sun.  You’ll need to keep moving to maintain your orbit.  The closer you are to the Sun, the more you’ll have to fight the Sun’s gravity, and thus the faster you’ll have to move.  Mercury is the closest planet to the Sun; ergo, he’s the fastest.  (If you’d like to learn more about the math behind planetary motion, click here.)

Since Mercury is the planet closest to the Sun, you might assume Mercury is also the hottest planet.  But no, Venus is hotter than Mercury (how that happened is a story for another time).  However, Mercury does have the #1 most extreme difference between daytime and nighttime temperatures.  Daytime temperatures climb as high as 430 degrees Celsius (800 degrees Fahrenheit).  At night, the temperature rapidly drops as low as -180 degrees Celsius (-290 degrees Fahrenheit).  Why?  Because Mercury has virtually no atmosphere.  Atmospheres are like insulating blankets for planets.  Without an atmosphere, Mercury can’t retain heat at all, so all the extreme heat Mercury gets during the day is immediately lost to the vacuum of space at night.  (To learn more about Mercury’s daytime vs. nighttime temperatures, click here.)

There are plenty more ways Mercury is #1, but I’m only going to share one more with you today.  Mercury is the #1 most heavily cratered planet in the Solar System.  How did that happen?  Well, once again, Mercury has no atmosphere, which means all the smaller meteoroids that would burn up in the atmospheres of other planets make it straight through to the ground on Mercury.  Additionally, there’s very little geological activity on Mercury.  No volcanic eruptions, no major earthquakes (mercuryquakes?)… at least not in the last 3.5 billion years.  On other worlds, geologic activity helps erode and erase old impact craters, but that’s not happening on Mercury.  So Mercury gets hit more easily and has a harder time erasing old impact craters.  Those two facts add up to Mercury having more impact craters today than any other planet in our Solar System.  (To learn more about Mercury’s overabundance of craters, click here.)

In my humble opinion, Mercury doesn’t get as much love as he deserves.  I don’t know why that is, but I hope this post has piqued your curiosity and helped you appreciate Mercury a little bit more.  At the time of this writing, the BepiColombo space probe (a joint venture by the European and Japanese space agencies) has completed several flybys of Mercury.  If all goes according to plan, BepiColombo should settle into orbit around Mercury in November of this year (2026).  Here’s hoping BepiColombo will discover even more reasons to love the first planet from the Sun.

The art is today’s post is my own original work.  If you like my art, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting and clicking the “like” button on my work helps me a lot (and obviously, if you do decide to buy something, that helps me even more).  Thank you, friends!

Artemis II: She’s Not Like Other Missions

~ J.S. Pailly ~ 15 Comments

Hello, friends!

It’s been a couple weeks since Artemis II went to space, looped around the Moon, and returned safely to Earth.  One thing really surprised me during this mission: I didn’t hear many people whining about the cost.  Whenever important NASA stuff is in the news, I always hear a ton of people whining about the cost.  But this time, not so much!  Which leaves me wondering: why was Artemis II different?

The most obvious explanation is that while Artemis II was up in space, there was this other major news story happening down here on the ground.  Now this is not a political blog, and I don’t want to dwell on politics too long, but we can’t ignore the elephant in the room: the war.  Just before Artemis II launched, the U.S. started a war with Iran.  That war is wildly unpopular and also extravagantly expensive.  When we keep hearing about the government spending one or two billion dollars per day on the war, NASA’s budget of $24 billion per year doesn’t sound so bad.

But I don’t think that’s the only reason.  Space launches used to be rare and extraordinary events, but in the last few years, they’ve been normalized.  With private companies like SpaceX and Blue Origin in the game, launches happen all the time now.  There were something like 300 launches worldwide last year!  Artemis II was still something new and different and very, very special; at the same time, though, it was just another rocket launch.  If we’re going to have 300 launches per year, it doesn’t seem outlandish for one of them to be a Moon mission.

Do you think I’m right about this?  Was your experience similar to mine, or did you hear more grumbling and griping about Artemis II’s price tag than I did?  Let me know in the comments below.

I will acknowledge that I did hear one complaint.  It was some political pundit who said something like: “NASA just sent billions of taxpayer dollars to the Moon!”  There’s plenty I could say in response to that, but that statement conjured such an amusing mental image in my head.  So I’m just going to leave you with this:

WANT TO LEARN MORE?

It wasn’t just me who felt like Artemis II was different.  According to this article from Forbes, the vast majority of Americans support the Artemis program and followed the Artemis II mission closely.

If you want to know more about NASA’s budget, check out this article from the Planetary Society.  It’s a great resource, not only for understanding NASA’s budget in particular, but for understanding the U.S. federal budgeting process as a whole.

And if you’re up for some more academic literature, here’s a research paper from the journal Space Policy examining how the federal government sometimes does (and sometimes does not) listen to public opinion regarding space exploration.

Aliens Don’t Exist

~ J.S. Pailly ~ 6 Comments

Hello, friends!

Today, I’d like to tell you a little about my 6th grade science teacher.  Oh, I remember him well!  Just not for the best of reasons.  For the purposes of this blog post, let’s call him Mr. M.

So one day, Mr. M. was teaching us about the formation of the Solar System, about how the planets of our Solar System were created from a cloud of dust and gas swirling round and round the Sun.  During this lesson, Mr. M. told us that our Solar System is unique.  He told us that science had not yet discovered any other planets orbiting any other stars, and he hazarded to guess that science never would.  He said that maybe there are no other planets out there for science to find.

Imagine that!  In the whole big, wide universe, there are only nine planets (Pluto was still considered a planet at the time).  And furthermore, the only nine planets in the entire universe all happen to be orbiting the same star!  That sounds pretty silly today, with over 6100 confirmed exoplanet discoveries now in the books.  It was also a silly thing to say at the time.  This would have been in 1996.  The first two exoplanets were discovered in 1992, orbiting a pulsar.  A third exoplanet was discovered in 1994, orbiting that same pulsar.  And then 51 Pegasi b, the first exoplanet discovered orbiting a sun-like star, was discovered in October of 1995.

So not only would science prove Mr. M. wrong—it already had.

I think about Mr. M. whenever someone tells me we’ll never discover alien life.  I think about Mr. M. whenever someone tells me that maybe there’s no alien life out there for us to find.

Frankly, I think about Mr. M. every time someone claims science will never do this or never explain that.  I may not have learned much in my 6th grade science class, but that class did help me learn one thing: there’s a long history of science proving people like Mr. M. wrong.

P.S.: Mr. M. also told us the Internet was just a fad and everyone would forget about it in a few years.  Again, this was in 1996.

The art in today’s post is my own original work.  If you like my art, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting and clicking the “like” button on some of my work helps me a lot (and if you do decide to buy something, that obviously helps me even more!).  Thank you!

IWSG: An Insecure Science Communicator

~ J.S. Pailly ~ 21 Comments

Hello, friends!  Welcome to this month’s meeting of the Insecure Writers’ Support Group, a blog hop created by Alex J. Cavanaugh and cohosted this month by J Lenni Dorner, Victoria Marie Lees, and Sandra Cox.  Are you a writer?  Do you feel insecure?  Well, then this is the support group for you!  Click here to learn more and to see a list of participating blogs.

Each month, IWSG asks members a question.  The question is optional.  I usually skip it, but this month’s question stirred up some deep feelings and some deep insecurities, so I thought I’d better address that.  The question is:

Many writers have written about the experience of rereading their work years later.  Have you reread any of your early works?  What was that experience like for you?

I’ve mentioned before in these IWSG posts that I feel insecure about my role as a science communicator, given that I don’t have any formal scientific training or experience.  So it’s a little jarring, when I’m looking for information about a specific space/science topic, to see my own blog posts pop up in search results.  I sometimes forget, when I’m looking for information about a specific topic, that I’ve already covered that topic before.

Reading those old blog posts of mine—those blog posts I forgot I wrote—is not fun.  They’re pretty cringy.  The art (in my judgment) is bad, the writing is worse, and the jokes aren’t funny.  However, setting aside these issues of style, the substance of my old blog posts is surprisingly decent.  The important thing is this: I came looking for information about a specific space/science topic.  Sometimes it’s a super niche topic that nobody on the Internet would think to write about (except me, apparently).  And whatever information current me is looking for, past me provided it.  Past me also did a good job citing his sources, usually, so if I want to learn more, I can learn more.

I still feel insecure about my place as a science blogger on the Internet.  My writing could be better.  My art could be better, too, and my jokes need work.  But after rereading some of my old blog posts, I can feel reassured about this: I stick to the facts and communicate information well.  I’m at least doing that part of the job right.

Betelgeuse and Siwarha

~ J.S. Pailly ~ 6 Comments

Hello, friends!

I love space, but I also love language and words and names, and I especially love it when people put thought and care into the naming of things.  Betelgeuse is a super famous supergiant star in the constellation Orion.  For as long as I can remember, it was generally assumed that Betelgeuse was a loner.  A single star, all by herself, with no binary companion.  But now it seems that Betelgeuse does have a very small, very faint companion star, which astronomers have (very aptly) named Siwarha.

Back in 2019/2020, astronomers noticed Betelgeuse start to flicker and dim.  There was a rapid 30% decrease in Betelgeuse’s brightness, leading to rampant speculation that Betelgeuse was about to go up in a supernova explosion.  That would have been an amazing sight for all of us here on Earth!  But then, nothing happened, and Betelgeuse’s brightness eventually went back to normal.

The Great Dimming of Betelgeuse, as this event is now called, was caused by something less spectacular than a supernova (less spectacular, but still interesting—check out the “want to learn more?” section below if you want to learn more).  Still, during the Great Dimming, Betelgeuse got a lot more attention from astronomers than usual, and astronomers started noticing patterns in her behavior—including a pattern that (based on reexamining historical records) seemed to repeat every 2100 days.

One possible explanation: maybe Betelgeuse has a companion star with an orbital period of 2100 days.  This hypothetical companion star was initially nicknamed “Betelbuddy.”  But then, in December of 2024, astronomers at the Gemini North Observatory in Hawaii were able to directly image “Betelbuddy” in mid-orbit.  At that point, Betelgeuse’s companion stopped being hypothetical, and somebody needed to give it a more official-sounding name.

Betelgeuse is an Arabic name (as most traditional star names are), and it means something like “the hand of the giant.”  The giant in question is, of course, Orion; however, the Arabic name for Orion is al Jawza, which is a female name from Arabian legend.  Therefore, since this newly discovered star circles round and round the hand of a lady giant, the Gemini North team proposed naming it “Siwarha,” meaning “her bracelet.”

How perfect is that?

Siwarha would have been hidden behind Betelguese during the Great Dimming, so it was not visible to Earth-based astronomers at that time, no matter how hard they looked for it.  Even after Siwarha emerged from behind Betelgeuse, spotting it stretched the limits of one of the very best telescopes in the world.  After crossing in front of Betelgeuse, Siwarha should appear again (on the opposite side of Betelgeuse) in late 2027, at which point astronomers should be able to learn much, much more about it.

WANT TO LEARN MORE?

Here’s a brief article published by NASA announcing the discovery of Siwarha.

And here’s a link to the actual research paper explaining how the Gemini North team detected Betelgeuse’s companion star.  The proposal to name it “Siwarha” is near the end of the paper.

As for the Great Dimming of Betelgeuse, it was caused by Betelgeuse burping a big, giant cloud of dust up into space, which partially obscured our view.  Click here to learn more about that.

P.S.: The art in today’s post is my own original work.  If you like my art, please consider visiting the I-Love-Space store on RedBubble.  Even if you don’t buy anything, just visiting and clicking the “like” button on some of my work helps me a lot (and if you do decide to buy something, that obviously helps me even more!).  Thank you!

Mission Statement

~ J.S. Pailly ~ 1 Comment

Hello, friends!

Today is New Year’s Day, so I thought today would be a great day to restate the mission statement of this blog—except it seems I never stated the mission of this blog in the first place.  I could’ve sworn that I had.  Maybe that’s because my mission seems self-evident.  I love space.  I love learning about space, and I love sharing what I learn with others.

The learning part is really important to me.  My love of space doesn’t mean just looking up at the stars and thinking, “Ooooh, pretty!”  I don’t enjoy wonder for wonder’s sake.  My love for space means looking up at the stars, wondering what’s up there, wondering who’s out there, and then putting in the time and effort to find answers (to the best of my ability as someone who’s bad at math and doesn’t have any professional scientific training).

Learning is hard.  Finding good sources of information can be tricky, and even when you do find trustworthy sources, science is still a challenging subject.  Scientists aren’t always the most engaging or entertaining communicators.  But if learning this stuff were easy, I don’t think it would be fun.  The greater the challenge, the greater the reward when you finally do understand a difficult and complicated concept.

So on this blog, I want to tell you about all the cool stuff I learn about space.  I also want to talk about the process I go through to learn this stuff, because the research process is part of the fun.  If you don’t know much about space, I hope to inspire you to love space like I do.  And if you already love space, then I hope to inspire you to love space even more!

But there will be some of you who don’t really care about space and never will.  I want you to know that that’s okay.  We can still be friends.  Not everybody has to love the same things.  I have an I.R.L. friend who’s not very interested in space, no matter how much I talk about it, but she paid me one of the very best compliments I’ve ever received: “You make me want to go learn stuff.”

That’s the real mission of this blog: to spread the love of learning.  I want to set a good example by picking a topic that fascinates me (space, obviously!) and learning everything I can about it.  For you, maybe it’s sports trivia, or Greek antiquities, or horses, or the history of music in video games, or the architecture of Frank Lloyd Wright… it doesn’t matter.  What matters is that learning is one of the greatest joys in life.  I love learning, and I hope you do, too.

Thanks for reading, friends!  Talk to you soon!

P.S.: If you like my art, click here to visit my art store on RedBubble.  Even if you don’t want to buy anything, just visiting and maybe clicking the “like” buttons on my art will help me a lot (and if you do want to buy something, that would help me a lot, too!).

3I/ATLAS: But What If It Were Aliens?

~ J.S. Pailly ~ 4 Comments

Hello, friends!

Right now, there’s an interstellar object passing through our Solar System.  Astronomers have named this object 3I/ATLAS, and in my last post I explained how 3I/ATLAS is just a comet and NOT an alien spacecraft.  But let’s pretend for a moment that an alien spaceship were traveling through the Solar System, perhaps on some sort of survey mission.  What would the aliens see when they turn their scientific instruments toward Earth?  How much would they learn about us and our planet?

Much depends on how technologically advanced we imagine these aliens to be, of course, but we humans have been observing Earth from space for decades now.  We know some things are pretty obvious about our planet, even when viewed from a great distance away.  For a start, the aliens would notice that Earth has an abnormally large moon.  They’d also notice that Earth has oceans.  The glint of sunlight reflecting off water would give that away.  And then there’s oxygen.  The spectrographic fingerprints of oxygen are all over Earth’s atmosphere.

Do these aliens breathe oxygen like we do?  Maybe, maybe not.  Either way, Earth’s oxygen-rich atmosphere would make the aliens stop and think, “Huh, that’s weird.”  Most planets don’t have atmospheres like that.  Even weirder, though, the aliens would also detect traces of methane in our atmosphere.  Methane is an easily oxidized chemical, so you’d think all that oxygen would oxidize any atmospheric methane out of existence pretty quick.  Something must keep replenishing the methane as quickly as oxygen destroys it.  Something alive, perhaps?  It’s hard to guess if the aliens would reach that conclusion yet.

As the aliens draw nearer, they’d soon notice this odd green stuff covering much of Earth’s landmasses.  To say that in a more technobabbly way, the extraterrestrials would detect a chemical substance with a strong reflection spectrum in green light (and an even stronger reflection spectrum in infrared).  You and I know what all that green stuff is, but would the aliens figure it out?  Do they have plants back home?  Do their plants contain chlorophyll and perform photosynthesis like ours do?  Hard to say, but Earth’s green stuff would at least make the aliens think, “Huh, that’s also weird.”

A few more things our hypothetical aliens would notice: a substantial ozone layer, continents shaped by recent (or possibly ongoing) tectonic activity, a complex hydrological cycle with water existing as a solid, a liquid, and a gas… oh, and radio emissions.  Lots and lots of narrow-band, amplitude modulated radio emissions, which cannot possibly be a natural phenomenon.

The idea that aliens many lightyears away are watching I Love Lucy, The Brady Bunch, or The Dick Van Dyke Show is probably false.  As radio/television broadcasts propagate through space, those signals grow weaker and eventually blend into the background radiation.  But for the purposes of this blog post, we’re imagining that an alien spaceship is right here in the Solar System with us.  They’re close enough to pick up our broadcasts.  At that point, the aliens wouldn’t just think, “Huh, weird.”  They’d be forced to conclude not only that life exists on Earth but that intelligent life exists on Earth (unless they start watching our news or listening to our talk radio; if they do that, they might second guess the “intelligent” part).

How much more could the aliens learn about us?  Again, it depends on how technologically advanced these aliens are.  Consider the stuff I listed in this blog post to be the bare minimum of what they’d know.

WHAT TO LEARN MORE?

This blog post is based off several research papers, which are listed below.  Detecting life on a planet—even a planet teeming with life, like Earth—is more of a challenge than you might realize.  If that’s a topic you want to learn more about, please check out some of the papers below, especially the first one (the one written by Carl Sagan).

The art in today’s post is my own original work.  I didn’t take it from the Internet or ask an A.I. to generate it.  If you like my art, please consider visiting my store on RedBubble.  Shopping on RedBubble is a great way to support artists (like me!) so that we can keep doing what we do.  Thank you!