Black Hole and Neutron Star are my favorite celestial body.

Honestly, our moon.

I firmly believe that our moon gives us the solar system in short order.

Fuel in the form of Helium-3 (if we can figure that out). Plenty of building material. Much lower gravity well that will allow larger payloads into it’s orbit and larger ships to be constructed. As well as that lower gravity well meaning better fuel efficiency in launching just about any trajectory to anywhere else in the solar system.

Once we have the Moon, we’re 90% of the way to a solar system spanning species. Mars is cool, but not useful in any real sense other than bragging rights.

The great attractor. It’s the biggest object we known of, but actually know almost nothing about. and it’s in a spot that’s hard to see through, our galaxy’s center. Almost everything we see in the sky is heading towards that point, hence the name.

Rogue black holes are terrifying

Magnetars. I want to throw an asteroid or something at one and watch it get ripped apart on a subatomic level purely by magnetism.

I am going to mention the rogue planets, since no one else has mentioned them here yet. Those unlucky celestial bodies ejected by their home star, destined to fly through the universe alone, dark and cold, forever.

Honestly earth.

Here is so much undiscovered that could help us understand space a lot better.

Lagrange Points (L4 and L5 specifically). Here’s a bit of space with a gravitational effect keeping you inside, but not due to mass inside it. It’s due to the relation of two other masses. Mind-boggling.

Venus. It’s got this mega-dense atmosphere. Why? It’s an anomaly when you compare it to the other similarly-sized planets in our solar system. The gas giants having thick atmospheres makes sense, but Venus? Actually, I just had a thought. The Sun’s mass generally pulls gas toward it. Gas that is in between the Sun and Mercury gets pulled into the Sun. Gas between Mercury and Venus gets pulled into the Sun too, since the closeness of the Sun makes its gravitational effect very influential compared to Mercury’s. Gas between Venus and the Earth, however, is far away enough from the Sun that it will stabilize around a Venus-sized planet. This explains the discrepancy between Mercury’s and Venus’s atmospheres. Not sure about the Venus/Earth discrepancy, but perhaps Mars’s light atmosphere is due to its lower mass.

Callisto. Why is it so dark? Why is the ice (the light splotches on the surface) like polka dots, rather than either an ocean or more diffuse?

I love space phenomenon in the same way as some people like scary movies, games, and environments. I feel a strong sense of dread and fear at the thought of black holes, white dwarfs, and neutron stars. It’s less about what you can see, and more about what you can’t.

It’s so bad that the most anxious and scared I’ve been in my life was on one of my first times using the FSD boost in the game Elite: Dangerous. In the game you can get boost to your ships travel by sucking up the streaming jets jutting out from white dwarfs and neutron stars. This boost can let you travel over 100ly, when average is 30ly or so. The process to do this, if done incorrectly however, can result in getting ripped out of cruising, stick, and unable to get away from these very disorienting beams before getting absolutely shredded. I have experienced nothing like it before or since.

To this day, neutron stars are both my favorite and most anxiety inducing universal phenomena! Slaughter House 5 is a really good book involving a neutron star, for those who haven’t read it.

My two biggest are probably Sol and voids. I wish I could directly observe the phase transition as you approach the star’s core, understand it’s corona patterns and behavior, observe deeper to predict CMEs, etc it’s just so close and present in our daily lives and still very mysterious. For the voids I’m not sure maybe because it’s defined by its boundary more than its contents, but they are pretty common and some are huge and it’s just difficult to study something that is defined by its lack of something.

Primordial black holes and rogue planets.

Black Holes are infinitely fascinating!

They’re ’a thing’ we knew nothing about until Einstein wrote a paper, and even though his own math showed their existence, he doubted that they could be real.

Turns out that they are, and that they form the structure of the entire universe.

That’s my object.

My favorite thing is Quantum Field Theory! You know the field of magnetism, you played with it as a kid when you got your hands on two magnets the first time.

Turns out every particle in the standard model has its own field, and an excitation of that field manifests as that type of particle.

David Tong explains it masterfully: https://youtu.be/zNVQfWC_evg

As does HOTU: https://youtu.be/UYW1lKNVI90

EDIT: Both links above are 1+ hours each, and done in layperson terms. No degree needed, just a desire to learn something fascinating.

I find neutron stars fascinating. The remnant of a star that was almost big enough to form a black hole but not quite. The gravity pulls all the matter left after a supernova into a bizarre form of matter. The protons and electrons are smushed together making basically the whole thing neutrons. They’re packed together so densely, a teaspoon would weigh as much as a mountain. A star much bigger than the sun suddenly condensed into like 20km.

Plus, some form pulsars spinning so fast that it seems impossible. The record is over 1,000 rotations per second. Some form magnetars, the strongest magnets in the universe. There might be an even more exotic form of matter — “strange matter” made of strange quarks — in their core.

Super Earths, because we know so little about them. They are the most common planet type (based on census from Kepler and TESS), but our solar system doesn’t have one, so we have no idea what they are like. Models and simulations give a few possible compositions, resembling mini-Neptunes, or water worlds with thick oceans, or more like Earth. Maybe all are possible. Earth-like rocky super-earths may be more geologically active than Earth, due to stronger convection and thinner crust. If they orbit a K-type dwarf, they could be candidates for super-habitable planets, with conditions even better for life than Earth.

The idea behind the heliosphere and all its related parts are really interesting. Something about a giant space bubble/teardrop flying through the galaxy that blows my mind. Learning about termination shock and the sink basin example really gave off this weird sense of cosmic grandeur that can be somewhat replicated on earth. As above so below kinda thing.