Science + Pop Culture, writing

Yakko’s Exoworlds

I do like a good Animaniacs song. Not gonna lie, I do have “The Nations of the World” memorized…even though it’s horribly outdated.
I am also all for music that conveys scientific information. But when you’ve got a piece of fictional entertainment, you’ve always got to worry that not all of the information is accurate — or noticeably inaccurate.
So here’s a combination of fact-check of and elaboration on the lyrics to the song in Season 2 Episode 6 Sketch 1: Yakko’s Big Idea (The writers being a’judged: Lucas Crandles & Timothy Nash)

How much did they get right?

Find out below!

Not long ago we didn’t know if we were all alone /
Was there a death of other Earths in the Habitable Zone /
Then the Kepler telescope found new hope in the Milky Way /
So why not try the cosmic sky for your next holiday?

For those unfamiliar, the Habitable Zone (or HZ) is the region away from a star where an Earth-equivalent planet (atmosphere and all) could have liquid water on its surface. The smaller (and therefore cooler) the star, the nearer the HZ is to its star, and the narrower the band of distances it covers.

Credit: NASA/JPL-Caltech/Lizbeth B. De La Torre

The thing people tend to forget is that the HZ varies for each individual planet. A planet with a thicker atmosphere than Earth’s, or with a greater abundance of greenhouse gases, couldn’t get as close to its star as Earth could while remaining habitable, because it would overheat.

Astronomers are in the very early stages of studying exoplanet atmospheres, because they’re so darn far away. So every time you hear a news story about a planet found in the HZ, it doesn’t automatically have liquid water on its surface. It might not even have an atmosphere!

Anyway, Kepler was indeed an exoplanet-hunting telescope, operating between 2009 and 2018. It’s responsible for finding the majority the exoplanets in our catalog to date — detecting them using the Transit Method. That means it monitored the brightness of a star over years and years, and a regularly occurring dip in that starlight signal indicated the presence of a planet temporarily passing between the star and Kepler’s metaphorical eye. Kepler was crucial for opening up the diversity of exoplanets, and planetary systems out there.

For the record, this is a more accurate depiction of Kepler:

However, as the song heavily implies, Kepler did not find 51 Pegasi b (Not, as Yakko calls it, Pegasi 51-B). That was the success of the Observatoire de Haute-Provence telescope in France, in October 1995. Well, that and the two dudes actually doing the observations, Michel Mayor and Didier Queloz. Their discovery earned them a share of the 2019 Nobel Physics Prize.

In fact there’s one that’s super fun just a few light years away /
Where one full year will disappear in 4.2 Earth days /
So if there’s only one place you’ve got space and time to see /
Then be astounded by the first we found it’s planet Pegasi 51 b

There’s a lot to fact-check here. First off, “few” is subjective, but on the scale of an entire galaxy, 50 light years is pretty close to us — the nearest star, Proxima Centauri, is 4.25 light years away.

Meanwhile, the orbital period of 51 Peg b (as it’s legitimately abbreviated) is indeed about 4.2 Earth days, or about 101.5 hours.

However, 51 Peg b was not the first exoplanet we found! In 1992, two planets were found orbiting a pulsar (the rapidly spinning dead core of a star that had gone supernova); a third was found around the same body in 1994.

51 Peg b is the first exoplanet found orbiting a star on the Main Sequence, meaning it’s still in the prime of its life.

But before you go ,you ought to know it’s kinda tough to get around /
Because the planet’s really gassy. There’s no land or solid ground /
Clouds of methane meet sulfuric rain, and when those are combined /
The air that you’ll be breathing there will smell like gas of another kind.

One note on the color choice in the image above. 51 Pegasi, the star around which 51 Peg b orbits, is almost identical in type to our Sun, so it shouldn’t be yellow, but off-white. The green is also highly suspect, because while we don’t actually know its entire chemical makeup, it’s a large gas giant, and will probably be closer in color to Jupiter. Check mark on the “really gassy” at the very least.

Importantly, there is actually a lack of evidence of methane (meaning scientists looked for its signature but didn’t see anything). So, quite a fail in that regard.

However, there are two notable gas giants in our own solar system with “significant” amounts of methane. Uranus and Neptune are still mostly hydrogen and helium (like their larger siblings, Jupiter and Saturn), but their atmospheres weigh in at about 2–3ish percent methane. That’s why these planets are blue in color (not green): methane molecules absorb red light.

Meanwhile, the sulfuric acid rain belongs to Venus. Which is not a gas giant. But I wouldn’t want to go there for a relaxing holiday, either.

[speaking] Gas, no good? Alright, gas isn’t everyone’s cup of tea. That’s fine. But what about one with aliens? Lady and gentle-boy, I give you Kepler-186f!
[back to singing] Okay, I jest, I kinda guessed whether E.T.s are alive /
But this hip spot has got the lot for aliens to live and thrive /
If there’s water here, it’s crystal clear, and not too hot or cold /
And it may contain amazing veins of pure and flawless gold!

Kepler-186f is totally a real planet, and that’s actually its name. It was the first Earth-sized planet found in its star’s HZ (again, based on that planet being an Earth, but that’s why the song references water being “not too hot or cold”). But this section of the song is mostly fantasy, and probably derives from artists’ depictions of the planet, which look like this:

Image Credit: NASA Ames/SETI Institute/JPL-Caltech

All we actually know about Kepler-186f is its radius: 1.17 times that of Earth. We don’t actually know its mass — assuming it’s made up of the same stuff as Earth, it would be about 1.4 times heavier. But we don’t know its composition, gold or otherwise. We don’t know if it has an atmosphere, breathable or otherwise. It could turn out to be an ocean world with a super thick atmosphere. Or it could be a lifeless hunk of rock.

And at over 500 light years away, it’s too far for our next-gen telescopes (like James Webb) to study its atmosphere, if it even has one. Which is a huge bummer.

However, one team of researchers did suggest it could maybe have seasons. But that’s based on computer models. So no need to pack your skis and bathing suit just yet.

But its sun is dying and amplifying all the harmful cosmic rays /
And the planet’s visage is forever barraged with all these brutal gamma waves /
If any E.T.s were alive, none would survive the radiation /
So it’d be astute to pack a hazmat suit for this hot new destination

Kepler-186 is a red dwarf star (So, the color’s wrong again), estimated to be about 4 billion years old — that’s younger than our own Sun by about half a billion years. Red dwarfs, being way less massive, live waaaaaay longer. This star will outlast our own, perhaps by a trillion years. It is definitely not dying, at least any more than a healthy 2 year old human is dying.

In fact, baby red dwarfs (millions, not billions of years old) throw tantrums in the form of ultraviolet, x-ray, and yes even gamma, radiation. Each of these are different types of light (more energetic than the visible stuff). That radiation is indeed harmful to life because it can damage and/or destroy complex molecules, like DNA.

Cosmic rays, meanwhile, are made of massive particles (not massless ones like photons), mostly comprised of lone protons (hydrogen nuclei) and alpha particles (helium nuclei). Red dwarfs can shoot those out too, but that’s not the radiation that astrobiologists are usually talking about in terms of threatening exoplanet habitability.

All that said, “if E.T.s were alive” on a red dwarf-orbiting exoplanet — at least the creatures as complex as the video depicts — they would have evolved to tolerate the radiation, because species that couldn’t live would have eventually died out.

The rest of the song is about an obviously made-up planet, so I include the lyrics here merely for completion’s sake:

[Speaking] Okay, so the radiation’s also a deal breaker, is it? Okay, well, it’s good to know. Hmm… alright, I got it!
[back to singing] And at lucky last, you can’t look past this place that shouldn’t be missed /
It’s always sunny, there’s magic puppies, and homework doesn’t exist /
The sailing’s dandy, the ocean’s candy, you can fly a broom /
But do not fear because the atmosphere will smell like sweet perfume /
And astronomers claim that video games have been built into every crater /
Why not play Asteroids all day and order pizza from an alien waiter? /
Or try a shopping spree ’cause everything is free, and bedtime’s not till eleven /
WB-1, the home of fun. Welcome to cosmic heaven!

After the song ends, Wakko asks, “Aren’t all these planets billions of miles away”. That’s a bit of an understatement. The closest exoplanet, Proxima Centauri b, is roughly 25 trillion miles. (For reference, Neptune is about 2.8 billion miles from the Sun, give or take, and that’s the outermost planet in our solar system.)

I know that ultimately this is an animated comedy sketch, but I went into this song hoping for so much. The writers clearly did some amount of research. But there were so many mistakes I just have to wonder why they even bothered? Why didn’t they ask an expert for some reasonable alternatives after they put a draft together? It could have been so much better!

(Also, one note on the nomenclature, technically Yakko shouldn’t be using capital letters at the end of these planet names. Lowercase letters are for planets. Uppercase letters are for other STARS!)

For a list of potentially terrestrial worlds in the habitable zone, visit

For NASA’s space tourism posters, visit and