Texas vs TNOs – Just How Big IS Texas?

Looking up something else about Trans-Neptunian Objects (TNOs), I stumbled on an interesting page with a very interesting graphic. That leads to an interesting question and answer.

Some Background:

I’ve driven across the USA more times than I can remember. Not nearly as many as long haul truckers, but quite a few. First time was at about 3 years old (Dad did a marathon drive back to Iowa has HIS Dad was dying and this was the only chance for him to see our family and us to say goodby. That was the first time I ever saw snow. Out the back of a Chevy Stationwagon – circa 1956 or 57 model year. Still remember the experience too.) Later, about college years, I did it two more times. Once in a ’67 VW Fastback about ’73, another in a Honda Accord (1976 – the first shipment date). Then it starts to get fuzzy. A couple of more times with my family. Another half dozen times or so going to jobs in Florida. And a couple of others. The point? I’ve driven coast to coast A Lot. I know just how big this place is, and just how long it takes to cross it.

Now some folks don’t. They have been spared the experience either by lack of opportunity, or so much opportunity they can just fly over it. You miss a lot that way. For one thing, during the Nixon Stupid Years when we had the Federal 55 MPH speed limit imposed, one Texan wisecracked that crossing Texas at 55 was not a journey, it was a career… I tend to think him right. There’s a lot to experience at 55 for about 20 hours… But I don’t recommend it.

It’s about 908 miles from the Louisiana edge to the El Paso point. (Not that I’ve watched the odometer and / or mile markers every single time ;-) That’s about 1460 km for those who are impaired by the metric system…) It is fully 1/3 of the drive from Silicon Valley to near Orlando Florida, and slightly more than 1/3 of ‘edge to edge’ starting in L.A. and ending at the Atlantic. In short, Texas is big. Very big.

So with that ‘set up’, just how big is it? Big enough to be a dwarf planet…

This site has a lot of interesting things, beyond just this one image.


Comparison of the largest TNOs

by Wm. Robert Johnston
last updated 15 March 2015

The image below compares the sizes of the largest outer solar system objects. It includes:

the Earth, the Moon, and Mercury (the smallest planet other than Pluto), for reference;
the three largest asteroids: (1) Ceres, (2) Pallas, and (4) Vesta;
Triton, the largest moon of Neptune;
Pluto, its large moon Charon, and its smaller moons Hydra, Nix, Kerberos and Styx;
(136199) Eris and its moon Dysnomia;
(136108) Haumea and its moon Hi’iaka and Namaka;
(136472) Makemake;
the distant object (90377) Sedna;
the 46 other known trans-Neptunian objects that are at least 500 km in diameter–at least as large as the three largest asteroids–and their 7 known moons;
the ringed object (10199) Chariklo;
the triple object (47171) 1999 TC36; and

the U.S. state of Texas for comparison.

Relative sizes, brightnesses, and colors are shown.

Earth vs. TNOs and with Texas for comparison

You will find Texas centered just under the Earth and in between Pluto / Charon and Mercury.

Note that it is about the same size as Ceres and Sedna, larger than Vesta and Pallas, and only modestly smaller than Makemake and Haumea. IMHO, if you included the wedge of the Earth under Texas all the way to the core, it would likely be larger and outmass all of them.

Somehow it gives it perspective to realize that if Texas were in orbit on its own, it would be a dwarf or minor planet, or a fairly large moon (depending on what it was orbiting).

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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12 Responses to Texas vs TNOs – Just How Big IS Texas?

  1. Another Ian says:


    I’m not arguing for a spot for Australia on that diagram but the areas of states here


    lets those of us in northern Australia particularly say we appreciate that “career” comment. At least we’re mostly allowed 100kph with the NT above that at around 130 kph

  2. Ralph B says:

    There are a couple non-TNO’s there. That being the case it would have been nice if Titan was included. This gives a nice reference as to how big our moon is in comparison to the others.

  3. Pingback: Texas vs TNOs – Just How Big IS Texas? | Climate Collections

  4. At first, in your article, I thought you’d be comparing the Texas land area with that of those objects. But you’re only comparing the disks. So using A = 4 Pi r-square, you get the surface area of the object. It’d be interesting to see a chart of that against the surface area of Texas. Just saying :).

  5. E.M.Smith says:

    @Ralph B:

    Unfortunately, as I didn’t make the graphic, it isn’t up to me.

    @Another Ian:

    It would be very interesting to see just such a graphic comparison. Maybe using several different Australian States, and maybe another one with some whole country comparisons. Australia, Canada, Russia, Brazil, United States, EU. All of them would be an “interesting size” on the chart.

    USA, Brazil, and China all ought to be about the size of the Moon. Australia, too, I think. Russia likely gets to the size of Mercury.

    Oh, and yes, the author of it starts with a heading that lists “TNOs”, but then in the description shifts to “outer solar system objects”… A kind of “bait and switch” but not too bad a one…

    Personally, I think the whole “dwarf planet” thing is a stupid kludge and I’d include Ceres, Pluto, Makemake (patron saint of Unix Programmers ;-) and even Sedna as planets. Heck, IF Charon is self rounded, I could see making Pluto / Charon a double planet system rather like the Earth Moon system.

    The problem with the definition is that it includes “cleared the local area” as a term. That means that what is a planet changes over time. Say a moon breaks up and scatters debris in a collision with a comet, is that planet now no longer a planet? Jupiter has Trojan asteroids, so really has NOT cleared it’s orbit. So why is it a planet? As the other asteroids collect into lumps (maybe on Ceres) and it clears that space, does it then become a planet? At exactly what point?… when it still has trojan like asteroids left? Just a can of worms.

    Make the rule “self rounding diameter and orbiting the sun” or “self rounding diameter and in a binary system where the barycenter orbits the sun” and you have something useful. (Heck, you can even arbitrarily set the diameter at 2000 or 2500 km based on some argument about when gravity will self round some standard rock like basalt). It eliminates that whole “depends on the evolutionary state of the neighborhood” political issue.

    So for my money, Eris, Pluto and even Sedna are planets… Though I liked it better when Eris was named Xena…

  6. w.w.wygart says:

    The way I look at it, land area seems important for the comparison in this discussion since driving around on its surface is what is important in the discussion. If you gather Texas’s 268,820 square miles of land area into a sphere, your would get an astronomical object of mean radius 146 miles – or 233km for those about to rush to their almanacs for comparison to other celestial objects. That’s between Hyperion and Miranda as somebody’s moon. Now somebody please check my math.


  7. p.g.sharrow says:

    I would think Alaska with an area Total: 663,268 sq mi, (1,717,856 sq km) would be a bit more respectable in size then puny Texas ;-) although a bit more remote. 3000 miles as you role a tire from Redding California to Anchorage, Alaska. pg

  8. Gary says:

    “Rhode Islands” are the standard measure for most journalists. It’s small enough (40 x 60 miles) that anything compared to it looks bigger because, after all , it IS a state. Texas is so big you don’t get nearly as much mileage out of the comparison. You can clear RI in a blink, even at 55mph. OTOH, if you want weirdness, there’s a lot more per square mile than in Texas.

  9. Chris says:

    I’m a British. As a student I journeyed around the U.S. in 1978. There were three of us and we used autodriveaway agencies and delivered cars. (Do you still have them?) I remember Texas well. My friends were unwell and I drove that leg on our drive from BoCA Raton to Orange County. I was caught for speeding (55 then) but off for being a British (our limit then 70). It took me 2 days to cross Texas. I still have pictures through the windscreen of roads disappearing to the horizon. A very enjoyable trip, but I couldn’t do it now at 66!

  10. Jason Calley says:

    Hey E.M. “Heck, IF Charon is self rounded, I could see making Pluto / Charon a double planet system rather like the Earth Moon system.”

    That brings up a question… many decades ago I read Azimov’s argument that the Earth-Moon system was a double planet. Why? Because the gravitational field of the Earth was a weaker influence on the Moon that was the field of the Sun. The Moon was orbiting the Sun more than orbiting the Earth, so it was a planet, not a moon. Now, maybe Pluto-Charon SHOULD be a double planet — after all, if they are both roundish, why shouldn’t they both be be planets? On the other hand, it is a loooooong way to the Sun, and I suspect that the gravitation field of Pluto is a far greater influence on Charon that is that of the Sun. Do we need two classes of binary planets? Double planets where each member is more strongly tied to the Sun than to each other, and perhaps binary planets where a pair of planets are more strongly influenced by each other than by the Sun? And then of course, you have the traditional planet-moon arrangement where one element is more strongly influenced by the Sun, and the second element is more strongly influenced by its associated planet.

    Or, we could be adults about the whole thing and realize that even in science, categories often have fuzzy edges! :)

  11. punmaster52 says:

    The mile markers are 880 at Louisiana to 0 at New Mexico on I-10, but who’s counting? :-)
    The preacher at my church had relatives in Texas. One day he mentioned taking three days to drive across I-10, and it took all I could do to keep from laughing out loud. When I drove an 18 wheeler, Texas was a day and a half across I-10 by myself. Not in the 55 mph years, of course.

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