mwahaha, an opportunity to ramble, my favorite
buckle up, because this is a long one
Section 1: The actual Star:
The Neuton Star (NOT NEUTRON STAR, i see so many people call it that, he specifically says Neuton) was created by Moon. It's said to be made using both tech and magic mixed together, creating something that is neither and both of the two at the same time. It is so complex that even Moon himself doesn't understand how he made it. (which leads me to believe quite a few of moon's greatest inventions were made powerpuff girls style)
Side note: The time at which Moon made this thing is a plothole I never noticed until now. It's implied to have been built prior to the show, but Moon doesn't learn magic until during the Eclipse 1.0 arc, and the only slot between him learning magic and the Star's first mention is taken up by his psychotic break.
In thumbnails, the Star is shown to be an actual five-pointed star, but fan interpretations tend to make it a glowing white orb with axis around it. Size varies in both.
I'll skip over the whole 'eclipse wants to become god' thing because I assume you know how that goes, and instead tell you why:
The Star, despite averaging around the size of a baseball, holds unimaginable power of creation. (This is important to note: the Star cannot destroy anything. It can create, and it can change things, but actually removing things from existence is a DPS only thing. Other than that, unlimited power) This power is granted to whoever currently possesses the Star, but is so powerful that it usually ends up physically degrading them. Its only true limitation is that it is completely useless outside of its home dimension.
Symptoms of Star Power Overdose Syndrome (SPOS) include: Dizziness, Unsteadiness when walking, Shaky hands, Shortness of breath, external monologues, and turning batshit insane. Talk to your doctor about treating SPOS today.
Also, a neat detail: In the episode of Eclipse 2.0's death, after he gets blasted into Solar's dimension, you can see that his body turns back into Solar Flare's because the Star Power he was using to look like Eclipse no longer works!
This power is implied to physically radiate off of the Star, and does so for such a wide radius that the computers can sense Eclipse coming almost a full minute before he gets there. The name given to this power is, unsurprisingly, Star Power. speaking of which...
Section 2: The Astrals and Star Power:
A lot of the Star Power stuff was already said in Section 1 so I won't repeat it. Instead, we're going over the Astrals.
Astrals are intergalactic godlike beings that both utilize and are composed of Star Power. They are immortal, possess various abilities including teleportation, telepathy, and flying, and have names/designs relating to space. There is implied to be a hierarchy of these guys, with the most powerful ones being the Zodiacs. These include Gemini, Leo, and Taurus.
I won't spend much longer going over them, because I don't think thats what you needed, but the biggest thing we can take from them is this: Even after a dimension's star is destroyed, Star Power and the flow of it throughout the universe is unaffected.
This makes me think the Star was a harnesser of Star Power, not the origin of it. Star Power does not come directly from the Neuton Star, but concentrates inside of it, allowing for the immense power we see in the show. Instead, Star Power is the physical essence of the universe, of creation itself, the energy that life draws from in order to exist.
This also explains why Star Power is stated to speed up a Dimension's heat-death the more it is used and abused.
Like I said, most other stuff about Star Power is in section 1, so onto my final paragraphs:
Section 3: Dark Star Power (DSP):
this one will be short bc im getting eepy
Dark Star Power is, as the name implies, the complete antithesis to Star Power. While SP is pure creation, DSP is pure destruction. It also has Astrals resonating within it, such as Rez and Kerian.
Something about DSP that always intruiged me was how it behaves like an infection, or a parasite. It spreads from host to host, grabbing on and not letting go unless taken out by force. It corrupts things in order to spread its chaos as far as possible. This is most clearly seen in Lunar's most recent arc
While Star Power is respesented with white, DSP is represented with glitchy purples and blacks. Along with being infectious in nature, possessing it causes similar effects to regular Star Power on top of the corruption and maddening.
thats all the words i got in me for tonight, i hope this gave you what you needed