You could fit all the planets within the average distance to the Moon.
I ran into this intriguing infographic over on Reddit that claimed that you could fit all the planets of the Solar System within the average distance between the Earth and the Moon.
I’d honestly never heard this stat before, and it’s pretty amazing how well they tightly fit together.
But I thought it would be a good idea to doublecheck the math, just to be absolutely certain. I pulled my numbers from NASA’s Solar System Fact Sheets, and they’re a little different from the original infographic, but close enough that the comparison is still valid.
So what could we do with the rest of that distance? Well, we could obviously fit Pluto into that slot. It’s around 2,300 km across. Which leaves us about 2,092 km to play with. We could fit one more dwarf planet in there (not Eris though, too big).
The amazing Wolfram-Alpha can make this calculation for you automatically: total diameter of the planets. Although, this includes the diameter of Earth too.
Soft drink sizes, SUV’s, baseball caps, hot dogs and truck nuts.
Astronomers mostly measure stars in terms of mass and use the Sun as a yard stick. This star is 3 solar masses, that star is 10 solar masses, and so on.
We’re pandering to those of you who want the most massive stuff as opposed to the most volumetric stuff. So if you want the biggest truck, but don’t care if it’s got the most truck atoms in one place, this might not be for you.
How massive can planets get, and where can I order a custom one more massive than a star?
It all depends on what your planet is made of. There are two flavors of planets, gas and rock.
Gas planets, like Saturn and Jupiter are pretty much made of the same stuff as our Sun.
Jupiter’s pretty big, but it’s actually only about 1/1000th the mass of our star. If you made it more massive. by crashing about 80 Jupiters together, you’d get the same amount of mass as the smallest possible red dwarf star.
And all that mass would compress and heat up the core and it would ignite as a star.
Artist’s View of Extrasolar Planet HD 189733b
Extrasolar planet astronomers have turned up some pretty massive gas planets. The most massive so far contains 28.7 times the mass of Jupiter.
That’s so massive it’s more like a brown dwarf.
But if you had a planet entirely made of rock, like the Earth. It would need to be much, much larger before its core would ignite in fusion.
It would need to be dozens of times the mass of our Sun.
Stars with 8-11 stellar masses can fuse silicon. So a rocky planet would need millions of times the mass of the Earth before it would have that kind of pressure and temperature.
So you could get a situation where you have more mass than the Sun in a rock flavored world, and it wouldn’t ignite as a star. It would get pretty warm though.
No star can burn iron. In fact, when stars develop iron in their core, that’s when they shut down suddenly and you get a supernova.
Feel free to collect all the iron in the Universe together and lump it into a ridiculously huge pile and no matter how long you stare at for, it’ll never boil or turn into a star.
It might turn into a black hole, though.
Artist’s impression of Kepler-10c (foreground planet)
The largest rocky planet ever discovered is Kepler 10c, with 17 times the mass of Earth.
Massive, but nowhere near the smallest star.
There’s new research that says that heavier elements blasted out of supernovae might collect within huge star forming nebulae, like gold in the eddies of a river. This metal could collect into actual stars. Perhaps 1 in 10,000 stars might be made of heavier elements, and not hydrogen and helium.
Metal stars.
So, it’s theoretically possible. There might be corners of the Universe where enough metal has collected together that you could end up with a star that’s made up of planety stuff. And that’s pretty amazing.
What do you think? If we found one of these giant metal stars, what should we call it?
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
One answer to the Fermi Paradox is the idea of the Great Filter; the possibility that something wipes out 100% of intelligent civilizations. That why we’ve never discovered any aliens… they’re all dead. Is that our future too?
In a previous episode, I presented the idea of the Fermi Paradox. If space is huge, like space huge, not aircraft carrier huge, and there are billions upon billions of stars, AND there seem to be lots of habitable planets around those stars, where are all the damn aliens?
Animation of Pluto and Charon showing nearly a full rotation (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)
Now here’s something I guarantee you’ve never seen before: a video of the dwarf planet Pluto and its largest moon Charon showing the two distinctly separate worlds actually in motion around each other! Captured by the steadily-approaching New Horizons spacecraft from July 19–24, the 12 images that comprise this animation were acquired with the Long Range Reconnaissance Imager (LORRI) instrument from distances of 267 million to 262 million miles (429 million to 422 million km) and show nearly a full orbital rotation. Absolutely beautiful!
For a close-up video of the two worlds in motion, click below:
Pluto and Charon rotation movie from New Horizons (enlarged view)
Pluto and Charon are seen circling a central gravitational point known as the barycenter, which accounts for the wobbling motion. Since Charon is 1/12th the mass of Pluto the center of mass between the two actually lies a bit outside Pluto’s radius, making their little gravitational “dance” readily apparent.
(The same effect happens with the Earth and Moon too, but since the barycenter lies 1,700 km below Earth’s surface it’s not nearly as obvious.)
“The image sequence showing Charon revolving around Pluto set a record for close range imaging of Pluto—they were taken from 10 times closer to the planet than the Earth is,” said New Horizons mission Principal Investigator Alan Stern, of the Southwest Research Institute. “But we’ll smash that record again and again, starting in January, as approach operations begin.”
Artist concept of the New Horizons spacecraft. Credit: NASA
Launched January 19, 2006, New Horizons is now in the final year of its journey to the Pluto system. On August 25 it will pass the orbit of Neptune – which, coincidentally, is 25 years to the day after Voyager 2’s closest approach – and then it’s on to Pluto and Charon, which New Horizons will become the first spacecraft to fly by on July 14, 2015, at distances of 10,000 and 27,000 km respectively. Find out where New Horizons is right now here.
Source: New Horizons
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
"The Chemistry of the Solar System" by Compound Interest's Andy Brunning
Here on Earth we enjoy the nitrogen-oxygen atmosphere we’ve all come to know and love with each of the approximately 24,000 breaths we take each day (not to mention the surprisingly comfortable 14.7 pounds per square inch of pressure it exerts on our bodies every moment.) But every breath we take would be impossible (or at least quickly prove to be deadly) on any of the other planets in our Solar System due to their specific compositions. The infographic above, created by UK chemistry teacher Andy Brunning for his blog Compound Interest, breaks down — graphically, that is; not chemically — the makeup of atmospheres for each of the planets. Very cool!
In addition to the main elements found in each planet’s atmosphere, Andy includes brief notes of some of the conditions present.
“Practically every other planet in our solar system can be considered to have an atmosphere, apart from perhaps the extremely thin, transient atmosphere of Mercury, with the compositions varying from planet to planet. Different conditions on different planets can also give rise to particular effects.”
– Andy Brunning, Compound Interest
And if you’re thinking “hey wait, what about Pluto?” don’t worry — Andy has included a sort of postscript graphic that breaks down Pluto’s on-again, off-again atmosphere as well. See this and more descriptions of the atmospheres of the planets on the Compound Interest blog here.
This artist’s view shows an extrasolar planet orbiting a star (the white spot in the right). Image Credit: IAU/M. Kornmesser/N. Risinger (skysurvey.org)
Is our Solar System normal? Or is it weird? How does the Solar System fit within the strange star systems we’ve discovered in the Milky Way so far?
With all the beautiful images that come down the pipe from Hubble, our Solar System has been left with celestial body image questions rivaling that of your average teenager. They’re questions we’re all familiar with. Is my posture crooked? Do I look pasty? Are my arms too long? Is it supposed to bulge out like this in the middle? Some of my larger asteroids are slightly asymmetrical. Can everyone tell? And of course the toughest question of all… Am I normal?
The idea that stars are suns with planets orbiting them dates back to early human history. This was generally accompanied by the idea that other planetary systems would be much like our own. It’s only in the last few decades that we’ve had real evidence of planets around other stars, known as exoplanets. The first extrasolar planet was discovered around a pulsar in 1992 and the first “hot jupiter” was discovered in 1995.
Most of the known exoplanets have been discovered by the amazing Kepler spacecraft. Kepler uses the transit method, observing stars over long periods of time to see if they dim as a planet passes in front of the star. Since then, astronomers have found more than 1700 exoplanets, and 460 stars are known to have multiple planets. Most of these stellar systems are around main sequence stars, just like the Sun. Leaving us with plenty of systems for comparison.
Artist’s impression of the solar system showing the inner planets (Mercury to Mars), the outer planets (Jupiter to Neptune) and beyond. Credit: NASA
So, is our Solar System normal? Planets in a stellar system tend to have roughly circular orbits, just like our Solar system. They have a range of larger and smaller planets, just like ours. Most of the known systems are even around G-type stars. Just like ours.….and we are even starting to find Earth-size planets in the habitable zones of their stars. JUST LIKE OURS!
Not so fast…Other stellar systems don’t seem to have the division of small rocky planets closer to the star and larger gas planets farther away. In fact, large Jupiter-type planets are generally found close to the star. This makes our solar system rather unusual.
Computer simulations of early planetary formation shows that large planets tend to move inward toward their star as they form, due to its interaction with the material of the protoplanetary disk. This would imply that large planets are often close to the star, which is what we observe. Large planets in our own system are unusually distant from the Sun because of a gravitational dance between Jupiter and Saturn that happened when our Solar System was young.
55 Cancri. Image credit: NASA/JPL
Although our Solar System is slightly unusual, there are some planetary systems that are downright quirky. There are planetary systems where the orbits are tilted at radically different angles, like Kepler 56, and a sci-fi favorite, the planets that orbit two stars like Kepler 16 and 34. There is even a planet so close to its star that its year lasts only 18 hours, known 55 Cancri e.
And so, the Kepler telescope has presented us with a wealth of exoplanets, that we can compare our beautiful Solar System to. Future telescopes such as Gaia, which was launched in 2013, TESS and PLATO slated for launch in 2017 and 2024 will likely discover even more. Perhaps even discovering the holy grail of exoplanets, a habitable planet with life…
And the who knows, maybe we’ll find another planet… just like ours.
What say you? Where should we go looking for habitable worlds in this big bad universe of ours? Tell us in the comments.
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
It seems like there’s a strange gap in between Mars and Jupiter filled with rocky rubble. Why didn’t the asteroid belt form into a planet, like the rest of the Solar System?
Beyond the orbit of Mars lies the asteroid belt its a vast collection of rocks and ice, leftover from the formation of the solar system. It starts about 2 AU, ends around 4 AU. Objects in the asteroid belt range from tiny pebbles to Ceres at 950 km across.
Star Wars and other sci-fi has it all wrong. The objects here are hundreds of thousand of kilometers apart. There’d be absolutely no danger or tactical advantage to flying your spacecraft through it.
To begin with, there actually isn’t that much stuff in the asteroid belt. If you were to take the entire asteroid belt and form it into a single mass, it would only be about 4% of the mass of our Moon. Assuming a similar density, it would be smaller than Pluto’s moon Charon.
There’s a popular idea that perhaps there was a planet between Mars and Jupiter that exploded, or even collided with another planet. What if most of the debris was thrown out of the solar system, and the asteroid belt is what remains?
We know this isn’t the case for a few of reasons. First, any explosion or collision wouldn’t be powerful enough to throw material out of the Solar System. So if it were a former planet we’d actually see more debris.
Second, if all the asteroid belt bits came from a single planetary body, they would all be chemically similar. The chemical composition of Earth, Mars, Venus, etc are all unique because they formed in different regions of the solar system. Likewise, different asteroids have different chemical compositions, which means they must have formed in different regions of the asteroid belt. Artist’s depiction of the asteroid belt between Mars and Jupiter. Credit: David Minton and Renu Malhotra
In fact, when we look at the chemical compositions of different asteroids we see that they can be grouped into different families, with each having a common origin. This gives us a clue as to why a planet didn’t form where the asteroid belt is.
If you arrange all the asteroids in order of their average distance from the Sun, you find they aren’t evenly distributed. Instead you find a bunch, then a gap, then a bunch more, then another gap, and so on. These gaps in the asteroid belt are known as Kirkwood gaps, and they occur at distances where an orbit would be in resonance with the orbit of Jupiter.
Jupiter’s gravity is so strong, that it makes asteroid orbits within the Kirkwood gaps unstable. It’s these gaps that prevented a single planetary body from forming in that region. So, because of Jupiter, asteroids formed into families of debris, rather than a single planetary body.
What do you think? What’s your favorite object in the asteroid belt. Tell us in the comments below.
One of my favorite pet peeves is the inability of conventional models to accurately convey the gigantic scale of the Solar System. Most of us grew up with models of the planets made of wood or plastic or spray painted styrofoam balls impaled on bent wire hangers (don’t tell Mommy), or, more commonly, illustrations on posters and in textbooks. While these can be fun to look at and even show the correct relative sizes of the planets (although usually not as compared to the Sun) there’s one thing that they simply cannot relate to the viewer: space is really, really, really big.
Now there are some more human-scale models out there that do show how far the planets are from each other, but many of them require some walking, driving, or even flying to traverse their full distances. Alternatively, thanks to the magic of web pages which can be any size you like limited only by the imagination of the creator (and the patience of the viewer), accurate models can be easily presented showing the average (read: mind-blowingly enormous) distances between the planets… and no traveling or wire hangers required.
Despite their similar apparent sizes in our sky, the Moon and Sun are (obviously) quite different in actual size. Which is a good thing for us. (Credit: Josh Worth)
Created by designer Josh Worth, “If the Moon Were Only 1 Pixel: A Tediously Accurate Scale Model of the Solar System” uses a horizontally-sliding HTML page to show how far it is from one planet to another, as well as their relative sizes, based on our Moon being just a single pixel in diameter (and everything lined up neatly in a row, which it never is.) You can use the scroll bar at the bottom of the page or arrow keys to travel the distances or, if you want to feel like you’re at least getting some exercise, scroll with your mouse or computer’s swipe pad (where applicable.) You can also use the astronomical symbols at the top of the page to “warp” to each planet.
Just try not to miss anything — it’s a surprisingly big place out there.
“You may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”
We’ve all seen charts showing the relative sizes of planets and moons compared to each other, which are cool to look at but don’t really give a sense of the comparative masses of the various worlds in our Solar System. It’s one thing to say the Earth is four times larger than the Moon, it’s entirely another to realize it’s 87 times more massive!
That’s where this new animation from astrophysicist Rhys Taylor comes in nicely.
It’s no mystery that the planets, moons, asteroids, etc. in the Solar System are arranged in a more-or-less flat, plate-like alignment in their orbits around the Sun.* But why is that? In a three-dimensional Universe, why should anything have a particular alignment at all? In yet another entertaining video from the folks at MinutePhysics, we see the reason behind this seemingly coincidental feature of our Solar System — and, for that matter, pretty much all planetary systems that have so far been discovered (not to mention planetary ring systems, accretion disks, many galaxies… well, you get the idea.) Check it out above.
