The Best Views in the Solar System

by Troy Jones III
(Huntsville, AL, USA)

I am working on a story whose opening scene is planned to be on Callisto with a view of Jupiter. When writing this scene, I thought, wouldn’t it be nice to know about how large Jupiter looms in Callisto’s sky in real life, to give my story just a touch of extra-gritty realness? Or, for that matter, to know how big all the various bodies of the Solar System appear when viewed from the other bodies?

Unfortunately, I couldn’t find a reference chart with this info. So, I have started putting one together myself. I am not a math person by any stretch of the imagination, but I know how to google haha. I found that to calculate the apparent size of something, one uses this fairly simple formula…

arctan(diameter/distance)

“Diameter” is the diameter of the object you are looking at. “Distance” is how far away it is. “Arctan” is a trigonometry function (inverse tangent); just look for a website that will calculate arctan for you haha.

Applying this formula will get you a number in degrees (or radians if you prefer), and one can get a sense of how this big or small something appears by using the same formula on common objects seen at arm’s length and comparing your results to each other.

Below is a table of views of various objects in the Solar System by vantage point and approximate apparent size when viewed therefrom, using the formula. As noted above, math is not my strong suit, so my calculations may very well be far off of the reality.

One thing to note is that, in real life, most people grossly overestimate the apparent size of objects in the sky. If you ask a random person how big the moon appears in the night sky, they will frequently say something like “a dinner plate” or “a softball” or even “a basketball”, but that isn’t even close to correct. In fact, you can easily hide the moon behind the tip of your pinkie finger held at arm’s length. One can only imagine what people would think of seeing something that actually does hang in the sky like a basketball, like Mars as seen from Deimos, let alone larger, like Saturn as seen from Mimas!

View of the Sun (865,000 miles diameter)
•from Vulcan (assuming ~20 million miles from the Sun): about two and a half degrees -- a ping-pong ball held at arm's length
•from Mercury (~42 million miles from the Sun): slightly more than one degree -- a U.S. penny (one-cent coin) or euro two-cent coin held at arm's length
•from Venus: can't see the Sun on account of the thick clouds (in fiction, the Sun is generally assumed to cause a diffuse glow in the sky at least)
•from Earth (~92 million miles from the Sun): about half a degree -- your pinkie fingernail held at arm's length (coincidentally, the Moon and the Sun have very nearly the same apparent size from Earth)
•from Mars (~138 million miles from the Sun): about a third of a degree -- an average-sized green pea held at arm's length
•from Ceres (~258 million miles from the Sun): about a fifth of a degree -- the head of a pin held at arm's length
•from Neptune/Pluto region (~3 billion miles from the Sun): about a sixth of a degree -- at this point, the Sun is not much bigger than a star, though still much brighter than a star (in fact, still bright enough to cause a twilight "day" in this part of the Solar System)
•from Ultima Thule (~4 billion miles from the Sun): about an eighth of a degree -- the Sun appears to be a bright star

View of Earth (7,926.3 miles diameter)
•from Luna (about 238,000 miles from Earth): slightly less than two degrees -- the Earth appears about the size of a U.S. half-dollar coin or British 50p coin held at arm's length

View of Mars (4,212 miles diameter)
•from Phobos (3,700 miles away): about 49 degrees -- about as big as a giant (90cm) beach ball held at arm's length (which is pretty dadgum tremendous)
•from Deimos (14,600 miles away): about 16 degrees -- a small watermelon held at arm's length

View FROM Mars looking up
•the view of Phobos (diameter 14 miles): takes up about a fifth of a degree, or about as big as a pinhead held at arm's length (fun fact: Phobos rises and sets about twice per Martian day due to its crazy fast orbital speed)
•the view of Deimos: it looks much like a star

View of Jupiter (143,000 miles diameter)
•from Io (about 217,000 miles away): about 29 degrees -- about like a medium-sized (45cm) beach ball held at arm's length
•from Europa (about 414,000 miles away): about 19 degrees -- an average-sized watermelon held at arm's length
•from Ganymede (about 665,000 miles away): about 12 degrees -- a cantaloupe held at arm's length
•from Callisto (about 1.1 million miles away): about 7 degrees -- a softball held at arm's length

View of Saturn (74,500 miles diameter excluding rings; outer diameter of the "A" ring is about 170,000 miles)

NOTE: Saturn's closest moons are lined up with the rings (indeed are part of the ring system), hence viewing them edge-on and from within, spoiling the view

•from Mimas (115,000 miles from Saturn): Saturn itself takes up about 32 degrees of sky -- equivalent to a 55cm pilates balance ball held at arm's length
•from Enceladus (148,000 miles from Saturn): Saturn itself takes up about 27 degrees -- equivalent to a medium-sized (45cm) beach ball held at arm's length
•from Titan: Titan's thick atmosphere would probably obscure the view from Titan

•from Iapetus (2,213,000 miles from Saturn):
◦ Saturn itself takes up slightly less than two degrees in the sky -- a U.S. half-dollar coin or British 50p coin held at arm's length
◦ The rings should appear to take up about 4 degrees of sky -- the diameter of a baseball or cricket ball held at arm's length (but disk-shaped instead of spherical, of course)
◦ The orbit of Iapetus is such that it should get a decent view of the rings (i.e. not edge-on)

•from Phoebe (~8 million miles from Saturn):
◦ Saturn itself takes up about half a degree -- your pinkie fingernail held at arm's length
◦ The rings should appear to take up about one and a quarter degree -- a bit smaller than a U.S. nickel (5-cent coin) or euro five-cent coin held at arm's length
◦ The orbit of Phoebe is such that it should get a decent view of the rings (i.e. not edge-on), though it is kind of far away

View of Uranus (~32,000 miles diameter)
•from Titania (271,000 miles away): about 7 degrees -- a softball held at arm's length

View of Neptune (~34,000 miles diameter)
•from Triton (220,000 miles away): about 9 degrees -- a shot-put held at arm's length

And (drumroll, please)... The prize for Most Dramatic View in the Solar System goes to... the view of Mars as seen from Phobos! (As if Mars hasn’t won enough of the awards on this site…)

Comments for The Best Views in the Solar System

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Jan 28, 2019
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Thank you for the kind words!
by: Anonymous

Thank you for the kind words, Dylan and Z. I also enjoyed y'all's contributions to Vintage Worlds. (And, "y'all's" is indeed a real word where I'm from.)

Jan 27, 2019
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"Them"
by: Dylan Jeninga

By "them", I mean Earth and Luna

Jan 27, 2019
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Lucky Starr and the Slightly Bigger Sun of Mercury
by: Dylan Jeninga

Hey, nicely done! Gotta hand it to ya for running the numbers on this one, I wouldn't know where to start. Seems "those who can" become engineers, and the rest of us are just stuck with our enthusiasm.

It's interesting to note that Luna is, apparently, visible from Mars with the naked eye, although unfortunately, nobody has ever enjoyed the view. Any hypothetical Martian astronomers would likely have named them, though, even if they didn't have telescopes.

BTW, Troy, I've read "Headless Skeletons", and I enjoyed it quite a bit. I know it's a no easy thing, but I hope you'll continue to write in the future!


Jan 26, 2019
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By Jove, you are right!
by: Troy

I mixed up the miles and kilometers for Jupiter. Revised apparent size of Jupiter in the skies of the Galilean moons is as follows...

Io: 22 degrees -- a big watermelon
Europa: 12 degrees -- a cantaloupe
Ganymede: 7 and a half degrees -- a softball
Callisto: 4 and a half degrees -- a baseball or cricket ball

(The error makes less difference the further away you are.)

The view of Pluto from Charon is indeed quite good. (Dunno why I forgot to do Pluto). Using km intentionally this time since that's what Google insists on giving me anyway regardless of what I ask for, a plutonian diameter of 2370km seen from a Charonian distance of 5087km yields about 25 degrees when plugged into the magic formula, or slightly bigger than the (revised) view of Jupiter from Io.


But, (and this caveat applies to Neptune and Uranus as well), the reflected light of the Sun is not much to write home about that far out. Pluto may be big, but it's probably not a particularly *bright* object in Charon's sky. (Then again, maybe things are so dark out there that even something not that bright in absolute terms seems to blaze, relatively speaking.) Something to keep in mind before making any vacation plans, in any event.

{Comment from Zendexor: I think your last two sentences hit the nail on the head: I'd be prepared to bet that dark-adaptation would soon make those distant worlds seem bright in each others' skies.

Tourist brochures could stress that the Pluto-Charon system is the only genuine double planet in the System - the Earth-Moon pair is sometimes termed a double planet but its centre of gravity is inside the larger body, whereas Pluto and Charon genuinely dance around each other from a point between.}

Jan 26, 2019
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superb views
by: Zendexor

This is a brilliant asset for those readers with inquiring minds - which, in our field, probably applies to all of us. Congratulations Troy. Although we must often put up with vagueness, and sometimes get fond of picturesque exaggeration (e.g. the huge appearance of Barsoom's moons in her sky) we're also fascinated to know the physical truth, and you have shown how to get it. (Charon from Pluto must be quite a sight, I imagine.)

One caveat: my National Geographic wall chart gives the diameter of Jupiter as 88,846 miles. (I think this is the equatorial diameter and that the polar diameter is about 83,000 miles.) Anyhow, your "143,000 miles" is maybe an accidental cross-ref from kilometers (drat the stupid things). I don't know if this affects your other Jovian-system calculations or if it's just a stand-alone typo.

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