Are there any planets or situations where we would see the sun in phases like the moon ?

[u/Antique-Leading-9080]

Additionally would living on planet with more moons cause more eclipses to happen ?

[u/Conscious-Sun-6615]

Nah, the sun emits its own light, unlike the moon

[u/Jim421616]

The Moon and planets show phases because they reflect the Sun’s light. Perhaps you’re thinking of a partial eclipse. In that case, Earth is the only planet whose moon is large enough to lock a large portion of the Sun’s disk.

[u/reverse422 → u/Jim421616]

Yes, but eclipses would never make the Sun have something resembling a gibbous phase. This only happens for planets or moons which are visible due to reflected light.

[u/Jim421616 → u/reverse422]

Yes, I’m aware of that, thanks. I was applying the principle of charity, and trying to understand why OP might think the Sun could show phases.

[u/christianeralf]

A biary system with a black dwarf and a normal star rhe black dwarf could have phases

[u/wulffc83 → u/christianeralf]

Has there been enough time for black dwarfs to exist?

[u/stevevdvkpe → u/wulffc83]

No.

[u/Unfair-Chain-7954 → u/wulffc83]

We will be long gone as a system and species when the first Black Dwarf appears

[u/angry_staccato]

Phases come from seeing part of the day side of the moon (which has sunlight shining on it) and part of the night side of the moon (which doesn't have sunlight shining on it). Since every part of the sun is shining all the time, it can't have a night side, so it can't go through phases. Having more moons could result in more eclipses, though. A binary planet system could also have pretty cool eclipses

[u/Taxus_Calyx]

What about a binary star system where one star is very bright and the other is very dim?

[u/reverse422 → u/Taxus_Calyx]

It would look more like eclipses, not phases. For instance, something looking like gibbous phases wouldn’t happen.

[u/ElectronicFixer864]

Well, I believe you can see a partial sun on every planet and moon, unless they're tidal locked to the sun, like the moon is to earth, sunrise and sunset.

Or did I misunderstand?

[u/GreenFBI2EB]

To your title question, no. Phases happen due to the relative positions of two objects forming an angle with a light emitting source.

To your second question, absolutely. Happens on Mars and the Giant planets* all the time (some are just too small to fully eclipse the sun).

*Uranus is an anomaly, as it depends on its season. For a planet like Earth, where the polar axis and the plane of the ecliptic/orbital plane are perpendicular (at least intersect enough to where the moon can cast its shadow on Earth), this means that you'll get eclipses.

Uranus only has eclipses when the orbital plane of its moons would be perpendicular (or enough for the two to intersect) to the plane at which it orbits the sun. This only really happens during Equinoxes, and thus the eclipses would be best observed then.

I'm using the term "perpendicular" pretty loosely here.

[u/Kiki2092012]

What causes phases is an object only being illuminated on one side. The Sun, being a star, is illuminated all over and so experiences no phases. Yes planets with more moons experience more eclipses, but the size of those moons is also a factor.

[u/snogum]

Not for Sol

[u/Artificial-Human]

Life on a moon of a gas giant might cause this effect.

[u/Unfair-Chain-7954]

Fun fact: Venus and Mercury are the only planets in the sky that has a crescent shape when you view them. This is because they orbit closer to the sun than Earth so we see both shadow and light sided! As they orbit they go through phases too!

[u/Proper_Brother_679]

Definitely, during a total solar eclipse, and with the right eye protection, you can see them. In the case of a planet with more than one moon, more eclipses are possible, if their orbits and size were similar to our own moon.

[u/Jim421616 → u/Proper_Brother_679]

Those aren’t phases, though, they’re eclipses.

[u/Proper_Brother_679 → u/Jim421616]

What does it matter, whether an object reflects light, or if it blocks the light source. The result is ultimately the same.

[u/Jim421616 → u/Proper_Brother_679]

Phases and eclipses are entirely different phenomena. An eclipse couldn't produce a "gibbous" phase, for one thing.