Is Earth The Only Planet With Total Solar Eclipses?

On August 12, 2026, fortunate viewers successful and astir Greenland, Iceland and Spain—weather allowing—will beryllium capable to spot 1 of nature’s genuinely glorious sights: a full star eclipse.

Much has been written astir star eclipses (I wrote an article connected April 5, 2024, for Scientific American, myself), truthful I won’t belabor nan accustomed points. Instead I want to return a person look astatine a communal claim: that our Earth is typical because it’s nan only satellite successful nan star strategy wherever specified perfectly aligned star eclipses tin occur.

Eclipses dangle connected a awesome coincidence: nan sun is astir 400 times nan diameter of nan moon, but connected mean it’s besides astir 400 times farther distant from Earth. These 2 factors cancel each different out, truthful nan satellite and sun look to beryllium nan aforesaid size successful our sky. This intends we tin get full eclipses, during which nan satellite wholly blocks nan sun, but it besides intends nan satellite sometimes just barely blocks nan sun’s disk.

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That’s important. The sun is surrounded by its corona, an ethereally bladed ambiance of ionized state that extends for galore millions of kilometers. Normally invisible to us, nan corona abruptly leaps into position nan infinitesimal nan satellite blocks nan sun’s superb face. Arguably this is what makes a full eclipse truthful gasp-worthy: nan quality of nan gorgeous wisps and streamers of nan corona are extraordinarily beautiful and truthful uncommon to spot that immoderate group cry—yes, openly weep—at nan sight.

If nan satellite were smaller aliases farther from Earth, it would ne'er artifact nan sun’s face, and we’d ne'er spot nan corona. If it were bigger aliases person to us, it would besides artifact a important information of nan corona, severely reducing nan wide affectional impact.

This is simply a singular coincidence, but is it unique? Other planets successful our star strategy person moons; immoderate person many. So do immoderate person that typical ratio of region and size to create an otherworldly full star eclipse?

I did nan math. Let’s see!

Mercury and Venus person nary moons, truthful those are easy. No moons = nary eclipses.

Mars has 2 moons, a brace of spudlike rocks called Deimos and Phobos. Both are small, little than 25 kilometers wide, and moreover though nan sun is smaller successful Mars’s entity because of nan planet’s greater region from it, neither satellite tin afloat artifact it arsenic seen from nan surface. In fact, rovers connected nan aboveground of Mars person observed some moons walk successful beforehand of nan sun, and astatine best, Phobos (which is larger than Deimos and person to nan planet) covers only a fraction of nan star disk. We could technically telephone specified events annular eclipses—which hap erstwhile a moon’s evident size is smaller than that of nan sun, leaving a ringing of sun astir nan moon’s silhouette—but much accurately, these would beryllium called transits. Also, a Phobos eclipse lasts little than a minute! While it would beryllium astonishing to witness, a Martian eclipse would beryllium a ray protector of what we tin spot from Earth.

Moving connected (and outward), Jupiter is astir 5 times arsenic acold from nan sun arsenic Earth is, truthful our prima appears only 1 5th arsenic ample successful its sky. The satellite has 4 ample moons, each of which tin create a full eclipse—but Io is 5 to six times nan sun’s evident size, while Europa and Ganymede are some astir 3 times bigger. That intends they’d besides artifact overmuch of nan soul portion of nan corona, lessening nan effect. Callisto would beryllium astir half again arsenic large arsenic nan sun successful nan sky, truthful much of nan corona would beryllium visible, but still not arsenic overmuch arsenic we spot from Earth. Jupiter’s different moons are excessively mini aliases excessively distant to create a full eclipse. Earth wins this one.

Next up is Saturn, astir 10 times arsenic acold from nan sun than Earth is, pinch a dizzying array of moons. As pinch Jupiter, astir each of Saturn’s awesome moons would look astatine slightest doubly nan size of nan sun, rendering nan soul corona invisible. Most different Saturnian moons would beryllium excessively mini to make a full eclipse.

There’s an exception, however: Epimetheus, an irregular icy assemblage 130 × 116 × 107 km successful size. Its orbit is somewhat elliptical, averaging 151,450 km successful radius. When it’s straight overhead, arsenic viewed from Saturn’s equator, it would look to beryllium only somewhat larger than nan sun. But erstwhile it’s connected nan horizon, it’s farther distant (by astir Saturn’s radius of 60,000 km), truthful it would look smaller than nan sun. That intends that location betwixt nan two, it would look precisely nan aforesaid size arsenic nan sun! Even accounting for its irregular shape, this must still beryllium true.

And this intends nan declare of Earth’s characteristic is incorrect. There is astatine slightest 1 different spot successful nan star strategy wherever it’s technically imaginable to spot a well-aligned full star eclipse!

To beryllium fair, it wouldn’t beryllium arsenic astonishing a position arsenic we get connected Earth. For one, nan sun would beryllium tiny, truthful you’d request a scope to spot immoderate specifications during nan eclipse. For another, Epimetheus moves truthful swiftly successful its orbit that nan eclipse would past little than 10 seconds. Also, for illustration Earth, Saturn’s rotational axis is tipped comparative to its orbit. This intends eclipses could only hap astatine nan equinoxes, doubly each Saturnian twelvemonth of 29.5 Earth years. That’s a agelong clip to hold to spot specified a teeny, short-lived eclipse.

I whitethorn beryllium biased, but I deliberation Earth wins here, too.

I did flick further retired successful nan star strategy and recovered different case: Perdita, a mini 30-km-wide satellite of Uranus that, for illustration Epimetheus, tin perchance beryllium nan nonstop size of nan sun successful nan Uranian sky. The problem is, this moon’s diameter isn’t perfectly known, and it’s imaginable Perdita whitethorn beryllium excessively mini (or irregularly shaped) to ever create a full eclipse. Even if it did, nan eclipse would only beryllium astatine astir a fewer seconds long—plus, fixed nan magnitude of nan Uranian year, it would beryllium 42 years betwixt eclipses arsenic well.

Earth’s eclipses triumph yet again.

So, successful nan end, nan declare that we are nan only satellite to bask specified “perfect” star eclipses isn’t technically true, but they wouldn’t beryllium astir arsenic spectacular from these different worlds. (I person to statement that I’ve near retired various further possibilities: for instance, galore asteroids person moons, too, but astatine this constituent I time off those calculations to a scholar acold much dedicated—and patient—than I.)

Knowing location are different places successful our star strategy to witnesser full eclipses of our prima does thing to trim nan awe and majesty of this astonishing sight. If we stock it pinch different worlds, nan much nan merrier! Perhaps early astronauts will bask that view, but for me, correct now Earth is still nan champion spot to beryllium an umbraphile.